LB 134
Universal Monitor II
Program version V 1.00
and higher
ID No.: 62688BA2
Rev. No.: 02
08.04.2016
LB 134 Content
I
Contents
WORKING WITH THE USER'S MANUAL ................................................................. V
SAFETY INSTRUCTIONS ........................................................................................ VII
1. DESIGN AND MODE OF OPERATION OF THE LB 134 .............................. 1
1.1 Overview ......................................................................................................... 1
1.2 LB 134 Probes ................................................................................................ 3
1.3 Nuclides and Measurement Types ................................................................. 4
1.4 Measurement Results as Raw Data and Calculated Units ............................. 5
1.5 Background measurement .............................................................................. 9
1.6 Various Averaging Methods ............................................................................ 9
1.7 Important Measuring Parameters at a Glance .............................................. 10
2. SYSTEM DESCRIPTION .............................................................................. 14
2.1 Enclosure with Electronics Module ............................................................... 14
2.2 Operating and Display Elements .................................................................. 17
2.2.1 Design of the Display .................................................................................... 17
2.2.2 Function keys and their meaning .................................................................. 18
2.2.3 Warning Signals ............................................................................................ 18
2.3 Power Supply ................................................................................................ 19
2.3.1 Working with Batteries .................................................................................. 20
2.3.2 Working with Rechargeable Batteries and PSU ........................................... 20
2.3.3 Power Supply for External Probes ................................................................ 20
2.3.4 Power Supply and Program Memory ............................................................ 20
2.4 Data Interface ................................................................................................ 21
2.5 Scope of Delivery .......................................................................................... 22
2.6 Wall Bracket (Optional Accessories) ............................................................. 23
3. COMMISSIONING ........................................................................................ 25
3.1 Connecting the Device .................................................................................. 25
3.2 The First Control Measurement .................................................................... 26
3.3 Basic Parameter Setup ................................................................................. 27
3.4 Installation of Wall Bracket for Stationary Operation .................................... 28
3.5 Possible Problems during Commissioning .................................................... 29
4. SOFTWARE DESIGN AND OPERATION ................................................... 30
4.1 Software Design ............................................................................................ 30
4.2 Measurement Menu Display ......................................................................... 31
4.3 Key Functions ............................................................................................... 34
4.3.1 Labeled Push Buttons and their Function ..................................................... 34
4.3.2 Softkeys......................................................................................................... 34
4.4 Operation....................................................................................................... 35
4.4.1 Selecting Menus and Options ....................................................................... 35
4.4.2 Editing: Entering Numbers and Letters ......................................................... 35
4.4.3 Selecting Items from a List ............................................................................ 36
4.4.4 How to Access the System Menu ................................................................. 36
4.4.5 LED Indicators ............................................................................................... 37
5. CONTAMINATION MEASUREMENTS ........................................................ 38
5.1 Requirements for Contamination Measurements ......................................... 39
5.1.1 Function Check ............................................................................................. 39
5.1.2 Measuring and Saving the Background ........................................................ 39
LB 134 Content
II
5.1.3 Creating the Small Nuclide Table ................................................................. 42
5.1.4 Importance and Editing the Other Nuclide Parameters ................................ 44
5.2 Measurement of Contaminations .................................................................. 45
5.2.1 CPS Measurement ........................................................................................ 46
5.2.2 Measurement of Area Activities .................................................................... 46
5.2.3 Explanations on Raw Data and Calculated Units ......................................... 48
5.3 Measured Result as a Function of the Contaminated Surface ..................... 49
5.4 Exceeding of Limit Values ............................................................................. 50
6. SOFTWARE FUNCTIONS ............................................................................ 51
6.1 Measurement of Contamination, Activity or Doserate .................................. 51
6.2 Description of the Individual System Menu Items ......................................... 54
6.3 Use Internal DR Detector .............................................................................. 55
6.4 Background ................................................................................................... 55
6.5 Measurement Mode ...................................................................................... 59
6.6 Measurement Parameters ............................................................................. 59
6.6.1 Ratemeter...................................................................................................... 59
6.6.2 Counter/Timer ............................................................................................... 61
6.6.3 Search ........................................................................................................... 62
6.7 Nuclides/Measurement Types....................................................................... 62
6.8 Integral Reset ................................................................................................ 67
6.9 Display Mode ................................................................................................ 68
6.10 Upload and Download Memory and Parameters .......................................... 69
6.11 Parameters .................................................................................................... 72
6.11.1 Date/Time ...................................................................................................... 72
6.11.2 Language ...................................................................................................... 73
6.11.3 Device Address ............................................................................................. 73
6.11.4 Calibration Type ............................................................................................ 73
6.11.5 Light Off [min] ................................................................................................ 73
6.11.6 Backlight ........................................................................................................ 73
6.11.7 Headphones/Relay ........................................................................................ 73
6.11.8 Power Supply ................................................................................................ 74
6.11.9 Hardware ....................................................................................................... 75
6.11.10 Factory setting ............................................................................................... 78
6.12 Alarm Type .................................................................................................... 78
6.13 Ticks .............................................................................................................. 79
6.14 Enable Menus ............................................................................................... 80
7. PROBES FOR THE LB 134 ......................................................................... 81
7.1 Internal Dose rate Probe ............................................................................... 81
7.2 Scintillator Probes with ZnS for Contamination Measurements .................... 81
7.2.1 Cleaning the Detector Window of Contamination Probes with Scintillator ... 83
7.2.2 Changing the Window Foil of Contamination Probes with Scintillator .......... 84
7.3 Contamination Probes LB 1231 and LB 1233............................................... 86
7.3.1 LB 1233 with Alpha-Beta P10 Counter Tube LB 6359 and Refill Station ..... 88
7.3.2 LB 1231 with Beta-Gamma Counter Tube LB 6357 ..................................... 93
7.3.3 Counter Tube Change ................................................................................... 93
7.4 Dose Rate Probe LB 1236-H10 .................................................................... 94
7.5 Neutron Dose Rate Probe LB 6411 .............................................................. 96
7.6 Neutron Survey Meter LB 6414 .................................................................... 97
7.7 Nal Scintillation Counter Probe LB 1234 ....................................................... 98
LB 134 Content
III
7.8 Activity Probe for Solid Samples LB 1238 .................................................... 99
7.9 Tritium Surface Contamination Monitor ...................................................... 101
7.9.1 Device Configuration ................................................................................... 101
7.9.2 Application ................................................................................................... 102
7.9.3 Probe Assembly .......................................................................................... 102
7.9.4 Counting Gas Supply .................................................................................. 103
7.9.5 Tritium Probe with Trolley ........................................................................... 105
7.9.6 Commissioning of Tritium Probe ................................................................. 106
7.9.7 Practical Hints for Operation and Measurement ......................................... 109
7.9.8 Performance Check .................................................................................... 109
7.9.9 Efficiency and Detection Limits ................................................................... 110
7.9.10 Working with the β-γ-Probe ......................................................................... 112
8. MAINTENANCE .......................................................................................... 114
8.1 Battery Replacement ................................................................................... 114
8.2 Charging Rechargeable Batteries ............................................................... 115
9. BASIS OF CALCULATION ........................................................................ 116
9.1 Calculating the Count Rate ......................................................................... 116
9.2 Ratemeter Function ..................................................................................... 117
9.3 Search Mode ............................................................................................... 118
9.4 Counter/Timer Function .............................................................................. 119
9.5 Determination of Calibration Factors in the Event of Contamination .......... 120
10. DECISION THRESHOLDS AND DETECTION LIMITS ............................. 123
11. APPENDIX .................................................................................................. 124
11.1 Calibration Factors for LB 1342 Scint-Contamination Probe (170 cm²) ..... 124
11.2 Calibration Factors for LB 1231 and LB 1233 ............................................. 128
11.3 Calibration Factors for LB 1341 (Xenon detector) ...................................... 129
11.4 Calibration Factors for LB 1343, Scintillation Detector (345 cm²) ............... 131
11.5 F²C Communication Protocol and Commands ........................................... 133
11.5.1 Status Definition in LB 134 .......................................................................... 133
11.5.2 Transmission Protocol ................................................................................. 135
11.5.3 Command Overview .................................................................................... 136
11.6 Parameter Locking with Jumper J3 ............................................................. 142
11.7 Pin Assignment of the Fischer Sockets ...................................................... 142
11.8 Example of RS485 Network with Multiple LB 134 as Dose Rate Monitor .. 144
12. TECHNICAL DATA LB 134 UMO II ........................................................... 145
13. INDEX ......................................................................................................... 146
LB 134 Content
IV
LB 134 Working with the User's Manual
V
Working with the User's Manual
A brief overview of the structure of this user's manual helps you
find important information quickly and easily:
Chapter 1 provides basic information on the design and the mode of opera-
tion of the LB 134, the measurement and averaging methods, and
the meaning of the displays cps and calculated measurement
units.
Chapter 2 contains a description of the monitor:
The design of the device with its control and display elements indi-
cators, the importance of the function keys and the different of
power supply options.
Chapter 3 describes how to take the LB 134 into operation.
Chapter 4 describes the structure and operation of the software.
Chapter 5 provides information on the contamination measurement: Prereq-
uisites of the measurement, measurement procedure and explanation of the individual types of measurement.
Chapter 6 documents all software functions of the LB 134 on the System
menu. This is the reference section of the manual.
Chapter 7 provides an overview of all probes that can be connected at this
time, including the data sheets.
Chapter 8 describes the maintenance works to be performed on the LB 134.
Chapter 9 provides information about the basis of calculation employed by
the LB 134 and the statistical accuracy.
In addition, the conversion of the measured unit from counts per
second to area activities is described so that you can determine
your own calibration factors using the specified formula and a calibration source and enter them in the LB 134.
Chapter 10 describes the statistical error, decision threshold and detection lim-
it.
Chapter 11 The Appendix contains the calibration factor tables.
Chapter 12 provides an overview of the technical data.
LB 134 Working with the User's Manual
VI
LB 134 Safety Instructions
VII
Safety Instructions
Use and Function The LB 134 is a versatile and flexible instrument designed for
use in radiation protection for contamination, activity and
doserate measurements.
The LB 134 can be employed wherever contamination, activi-
ties or doserates caused by radioactive substances occur and
are to be monitored:
In the medical nuclide laboratory, in radiation research, in nu-
clear power plants, and in the environment in general.
Special instructions If statutory provisions exist concerning the installation and/or
operation of radiation measuring devices, the operator must ensure that these regulations are complied with.
The manufacturer has done everything possible to guarantee
that the equipment functions safely. The user must ensure that
the LB 134 is set up and installed properly to ensure safe operation.
With regard to the detectors, please keep in mind:
Use caution when measuring rough or sharp objects to avoid
damage to the sensitive window foil of the contamination
probes.
Handle all detectors with care, as the detectors contain ei-
ther counting gas, a scintillator or a crystal.
Proper use and handling of the LB 134 requires that the user is
familiar with the user's manual. Therefore, user should read this
manual carefully before taking the device into operation.
To ensure the correct performance of the device we recom-
mend carrying out the tests and maintenance routines recommended by the manufacturer.
Any service and maintenance work above and beyond those
described in this user's manual must be performed by
BERTHOLD TECHNOLOGIES or by service technicians authorized
by BERTHOLD TECHNOLOGIES.
LB 134 Safety Instructions
VIII
LB 134 Design and Mode of Operation of the LB134
1
1. Design and Mode of Operation of the LB 134
1.1 Overview
The LB 134 is a versatile and flexible instrument designed for
use in radiation protection for contamination, activity and dose
rate measurements. It can be employed whenever alpha, beta
and gamma contaminations on surfaces such as floors, walls,
tables, objects, clothes or the skin, caused by radioactive substances occur and need to be monitored; moreover, it can be
used to determine the gamma and neutron dose rate. The contamination detectors with scintillator can be used to distinguish
alpha nuclides, on one hand, and beta and gamma nuclides, on
the other hand, and to measure them simultaneously. Furthermore, measuring probes are also available which can be used
to determine CPS values only, as in these cases calibration in
physical units is not possible for various reasons.
necessary electronic functions and interfaces, and an internal
gamma dose rate probe. As an alternative to this probe, a variety of different probes for different measurement tasks can be
connected externally; we then have a combination device that
consists of a basic unit LB 134 and one external probe each,
which is connected to the basic unit via a spiral cable. To extend the life of the batteries/rechargeable batteries, the supply
of the internal probe is switched off in the menu when not in
use. Nine different detectors can be connected to the UMO
LB 123 which has been on the market for many years; up to 15
detectors can be connected to the new generation LB 134. The
basic instrument identifies the connected detector either via a
code resistor (LB123 UMO probes) or via EEprom memory in
the detector, which communicates via a I²C bus. This means
that the older probes of the UMO LB 123 are compatible. After
the detector has been identified, the corresponding parameters
will be loaded from memory and measurements are performed
with these parameters. Each detector has its own set of parameters that can be changed via the LB 134 keyboard or via data
communication.
measurement functions either as a portable and/or as a semistationary device. Special holding devices are provided (e.g.
wall bracket). Single counter events can also be signaled
acoustically, alarms can be communicated visually and audibly
and can be switched on and off. Additionally, these signals can
also be sent to a headphone connected to the device via a jack
plug. In this case, the integrated piezo loudspeaker is disabled.
Alphas and betas can be distinguished acoustically by their
beeps of different lengths. The display backlight can be toggled
LB 134 Design and Mode of Operation of the LB134
2
on and off via a button. In the graphics mode, the measured
values can be represented as a function of time, in the ratemeter mode, you always see the graph of the last 120 seconds. A
separate jumper allows you to lock certain parameters optionally through the hardware, for example, background values or calibration factors in dose rate probes. The parameters are permanently stored in a memory chip powered by a long-life Li cell.
connector to allow communication with a PC or to connect a
memory stick. Two other functions can be operated via a separate 6-pin Fischer connector: An external low-voltage relay can
be connected, which is enabled when an alarm in the first or
second measuring channel is exceeded. This can be used in
the event of an alarm, for example, to operate a signal lamp.
Furthermore, an RS485 interface is available, allowing integration of the device into a local network. Up to 32 measuring devices, including central computer, can be integrated in this network with a cable length of up to 1000 m. The baud rate to be
set depends on the cable length and the number of connected
devices. The standard cable used is a shielded twisted pair data cable which has to be terminated at each end of the bus with
120 ohms.
The F²C protocol, which is also implemented in some other BT
devices, is used for serial data communication via RS485 and
USB interface. All parameters can be up- and downloaded with
this protocol. Many more features regarding measurement options are available. The device is fully remote controllable. Using a service program, a new program can be transferred via
USB interface to the device. A PC control program allows remote control and data transmission with archiving and many
graphics options and parameter upload and download. The
measurement data memory can also be transferred to the PC.
With the USB memory stick, the measurement data memory
can be transmitted and the parameters can be uploaded and
downloaded.
The device is optimally protected against environmental influ-
ences such as moisture, dust and temperature.
LB 134 Design and Mode of Operation of the LB134
3
1.2 LB 134 Probes
The integrated gamma dose rate probe LB 1346 is a Geiger-
Müller tube and is suitable for the low dose rate range from
0.1 µSv/h to 20 mSv/h and for an energy range from 50 to
1300 keV. Calibration factor: 0.625 µSv/h/cps, intrinsic background: 0.07 cps. The probe is calibrated to the H*(10) standard
(ambient equivalent dose rate). To extend the life of the batteries/rechargeable batteries, the supply of the internal probe is
switched off in the menu when not in use.
Currently, the following probes can be connected external-
ly using a coiled cable:
LB-number Detector type Application
LB 1231 Proportional counter tube, Xe gas βγ contamination
LB 1233 Proportional counter tube, P10 gas αβγ contamination
LB 1234 NaI crystal, 1" γ activity, only cps value
LB 1238 End-window proportional counter tube αβγ activity
LB 1239 Proportional counter tube, P10 gas Tritium contamination
LB 6411 He-3 proportional counter tube Neutron dose rate
LB 6411-1 He-3 proportional counter tube, Neutron dose rate
reduced pressure
LB 1236-H10 Proportional counter tube γ dose rate
LB 6414 He-3 proportional counter tube Neutron search
LB 6386 P10 proportional counter tube, large-area αβγ contamination
LB 6376 Xe proportional counter tube, large-area βγ contamination
LB 1342 ZnS scintillation detector 170cm² αβγ contamination
LB 1343 ZnS scintillation detector 300cm² αβγ contamination
LB 1341 Xe proportional counter tube 170 cm² βγ contamination
More detailed probe data can be found in chapter 7. The follow-
ing important probe dependent parameters are stored in the parameter sets for each probe: Calibration factors, dead times, allowed measuring ranges, alarm levels, units, fail thresholds and
more. The calibration factors for the contamination probes are
stored both for the older DIN 25415 standard as well as for the
more recent DIN ISO 7503 standard. The intrinsic background,
which is a detector property, is stored for the gamma dose rate
probes and should not be changed.
LB 134 Design and Mode of Operation of the LB134
4
1.3 Nuclides and Measurement Types
A separate calibration factor is needed for each nuclide to de-
termine alpha, beta or gamma contamination. We distinguish
between alpha and beta/gamma nuclides and assign a calibration factor to each nuclide. Betas and gammas are essentially
measured in the same measuring channel and cannot be distinguished alone with the detector. Since there are two different
definitions for the calibration of the detectors, according to the
DIN 25415 and DIN ISO 7503 standards, we need two calibration factors for each nuclide. The nuclide tables of the contamination probes contain about 70 nuclides with the following entries for each nuclide: Name, DIN and ISO calibration factor,
alarm threshold, type of radiation (α, β, γ or n), unit, integral
threshold, integral unit, time base for integration and status indication whether it is enabled. Before each measurement, you
have to select the desired alpha and beta nuclide so that the
correct settings are selected. DIN or ISO standard are determined on initial setup of the device by the supervisor and set in
the system parameters, and is then usually not changed any
more. Nuclides can be deleted or entered new or their parameters can be changed.
When using a gamma or neutron doserate probe, for example,
no nuclide data are needed because these probes are energy
independent and, therefore, nuclide independent in the defined
measuring range. You do not have to select a nuclide prior to
the measurement. Instead of a nuclide selection, the LB 134 includes a "measuring type" selection for these and similar
probes. Each measuring type also has, very similar to the parameters of a nuclide, a parameter set with almost the same entries; however, there is only one calibration factor. This can be
used, for example, to define one of the following measurement
types:
Dose rate 1:
With calibration factor for ambient dose equivalent rate
H*(10), unit µSv/h, thresholds as desired
Dose rate 2:
With calibration factor for ambient dose equivalent rate
H*(10), unit mrem/h, thresholds as desired (USA)
etc.
Of course, the correct calibration factors must be entered for
the parameters of the individual measurement types. Using this
method, one can very quickly change, similar to the nuclides,
the measurement types to adapt to the requirements of other
countries.
LB 134 Design and Mode of Operation of the LB134
5
1.4 Measurement Results as Raw Data and Calculated Units
The LB 134 is able to output raw data as counts per second or,
depending on the application, different measured physical
quantitities calculated using a calibration factor. Typical units for
calculation are for
Contamination: Bq/cm², pCi/cm²
Dose rate: µSv/h, mrem/h, µGy/h, R/h
For most probes, the calculation is very simple:
Measured value = Calibration factor * (gross rate – background)
Of course, the gross rate is corrected with respect to dead time
or linearity (as in a ZnS scintillator). The displayed accuracy of
the measurement due to counting statistics also takes into account the background and the background measuring time. The
uncertainty in the calibration factor is not included. In the counter/timer mode, the statistical accuracy G is:
(%)
In the ratemeter mode:
(%)
Where:
Rb gross count rate cps
Ro background count rate cps
Tp sample measurement time s
To background measurement time s
tau time constant s
With preset time constant (also see below under Ratemeter),
tau is the entered time constant, with preset accuracy, tau is determined every second from the current count rate and the entered accuracy. For a high accuracy, one should always measure the background as long as possible, e.g. one hour. With increasing sample measurement time in the counter/timer mode,
the accuracy is the better, the lower the accuracy value. In the
ratemeter mode with preset time constant, the accuracy, with a
given tau, also depends on the count rate. To get a higher accuracy with the same count rate, we need to enter a larger time
constant. With preset accuracy, you just have to enter a smaller
number.
LB 134 Design and Mode of Operation of the LB134
6
Two different methods are available to average the statistical
fluctuations in count rates. For searching of hidden radioactivity:
a ratemeter mode, where the average value traces the actual
rates somewhat delayed; for single sample measurements: a
counter/timer function where the counts are added up over a
fixed preset measuring time and divided by the elapsed measuring time after background correction.
Counts per second (cps)
In the simplest case, the LB 134 measures the radiation activity
in counts per second. Since the number of counts detected per
second is subject to statistical fluctuations, e.g. the abovementioned ongoing averaging (ratemeter) is carried out so that
the displayed value is matched to the count rate and the displayed measured value is less and less subject to statistical
fluctuations within a short measurement time.
Calculated unit of measurement in contamination
measurements
The simultaneous determination of alpha and beta contamina-
tion in two measuring channels is a rather complicated measurement method with this device and therefore has to be treated in more detail. The results of measurements with other
probes are always obtained in a very similar way, but in most
cases only through one measuring channel, e.g. dose rate
probes, Tritium probe or NaI crystal probe.
So, if the contamination is to be measured in Bq/cm² (i.e. activi-
ties per unit area), the count rate has to be converted to area
activities. The conversion factor is different for each nuclide.
The individual factors are stored in the device. In each case,
therefore, the nuclide or nuclide mixture to be measured must
be set on the device prior to measurement. One can set an alpha nuclide for the alpha channel and a nuclide with beta or
gamma radiation for the beta-gamma channel. The radiation
types are distinguished in the course of the measurement. The
measurement is performed at the same time.
This does not mean, however, that the LB 134 is capable of
measuring these nuclides selectively; rather, the monitor treats
contamination (i.e. the measured count rate) as if it were
caused by the respective radionuclide.
The conversion is based on calibration factors determined for
each nuclide. They are not only dependent on
- type of radiation,
LB 134 Design and Mode of Operation of the LB134
7
- radiation energy and
- decay pattern of the respective nuclide,
but other factors are also relevant, such as:
- detector sensitivity,
- measuring geometry,
- self-absorption in the source.
The calibration factor indicates the value with which the back-
ground-corrected gross counts per second must be multiplied to
obtain data displayed in Bq/cm².
Accordingly, a Bq/cm² measurement is only correct when the
set and measured nuclide match.
When setting the unit Bq/cm² and selecting the respective nu-
clide, the LB 134 automatically converts the measured cps to
Bq/cm². The software includes a (editable) nuclide library with
about 70 different nuclides and their calibration factors for
measurement of the area activity. Moreover, 9 empty positions
are available to enter the calibration factors for other nuclides.
What to do with unknown nuclides?
In practice, however, we often encounter a nuclide mix contain-
ing unknown or only partially known nuclides; let us, therefore,
consider the following alternatives:
Nuclide mix of unknown composition
If you do not know the composition, select a calibration factor
for alpha or beta sources which is calculated from the average
value of the alpha or beta sources which are most frequently
encountered after an accident in a nuclear power plant.
If you do not know the nuclides, use the setting ß-tot (beta to-
tal).
Nuclide mix of known composition
To measure the activities of several nuclides at the same time,
you can do the averaging yourself (if necessary with weighing)
and enter the calibration factor.
Another alternative is to set a so-called reference nuclide. This
means that you select an isotope with medium energy stored in
the nuclide library of the device which corresponds to the nuclide mix to be measured.
For non-contamination probes, there are various types of
measurements, instead of the nuclide table, which can be used
to quickly carry out various measurement tasks.
LB 134 Design and Mode of Operation of the LB134
8
Calculated unit of measurement in γ and n doserate
measurements
Currently, two probes with different energy-compensated counter tubes are available for γ or n doserate measurement; they
output the radiation effect as ambient equivalent doserate in
units of μSv/h (micro Sievert/h). The integrated probe LB 1346
is an energy-compensated Geiger-Mueller counter tube for the
range from 0.1 to 20,000 µSv/h and an energy range from 30 1300 keV. The external probe LB 1236-H10 is an energycompensated proportional counter tube for the measuring range
from 0.05 to 10,000 µSv/h and an energy range from 30 to 1300
keV. With the integration function, the doserate can be integrated over time to dose, with dose and integration time being displayed. The calibration factors, the dead times and the intrinsic
background have been determined by Berthold Technologies
and are already set in the device. The determination of the neutron doserate with the probe LB 6411 or LB 6411-1 is quite
similar to the method described here; a He-3 counter tube is
used to measure the thermal neutrons generated with the help
of a moderator through a nuclear reaction. Without knowing the
neutron spectrum to be measured, we get the correct neutron
doserate and the corresponding dose within a range from
30 nSv/h to 100 mSv/h.
Calculated unit of measurement in activity measurements
The LB 134 is used to measure the activity of samples (alpha,
beta and gamma radiation). One can also choose to display the
count rate (cps) or the decay rate (Bq/pCi/dpm, etc.).
In this function, the alpha-beta proportional counter tube
LB 1238 with end window (about 30 mm diameter) is used as a
detector. In contrast to conventional Geiger-Müller end window
counter tubes, the counter tube LB 1238 can distinguish alpha
and beta activities.
The samples are usually measured in the Counter-Timer
mode to achieve a high accuracy. The statistical accuracy or
the measurement time can be selected as a parameter for the
measuring time. Similar to the contamination measurement, in
this measurement mode you have to enter separate calibration
factors for each nuclide which match your measuring arrangement and the nuclide to be measured. In this measurement mode, the calibration factor is also determined using a
sample with known activity. The ratemeter mode is used in this
function, for example, for the rapid detection of radiation or radioactive sources, for example, in chromatography, to see if the
radioactively labeled sample already appears in the column.
LB 134 Design and Mode of Operation of the LB134
9
1.5 Background measurement
The background, the normal environmental radiation, is measured in cps. It is automatically subtracted from sample measurements. Gross and raw data values can be displayed on the
screen simultaneously. The background measurement can be
started automatically after switching on the device. The background should be re-measured every now and then; for sample
measurements requiring a high accuracy, we recommend to
measure the background directly before carrying out the sample
measurement. Since the size of the background and the associated measurement time affect the accuracy of a sample
measurement, the background should always be determined
using a long measurement time, e.g. 1 hour or more. The size
of the background itself depends on the detector and the shielding. If you know that radioactive sources are present in the
measurement environment, you should change the location for
the sample measurements and, of course, for the background
measurement.
1.6 Various Averaging Methods
The LB 134 features the following measurement modes:
a) Search Mode to quickly search for contamination,
doserates or activities. In this measurement mode, the device is very sensitive to different radiation activities and
shows changes very quickly.
b) The Ratemeter mode does not react as fast to differences
in activity, but is more accurate. In the ratemeter mode one
can work with a common time constant or the statistical accuracy. In the second case, the device calculates every
second a dynamic time constant from the entered accuracy
and the actual count rate which ensures that the measured
value reaches this accuracy. If count rate jumps occur, this
will not be true directly, but after a certain averaging time,
when the count rate is reasonably stable, the actual accuracy will approach the entered value. The measurement
time determines when measured values are stored or
transmitted. The number of cycles indicates how often
measured values are stored. The ratemeter has a dynamic
component that ensures that the displayed value tracks the
real value as quickly as possible if fast activity changes occur. Since some detectors such as Geiger-Müller counter
tubes may occasionally generate interference pulses outside the Gaussian statistics, an additional software burst filter has been added to avoid unrealistic activity jumps.
LB 134 Design and Mode of Operation of the LB134
10
c) The Counter-Timer mode is designed for a high accuracy.
The measurement time or the statistical accuracy can be
chosen as a measure of the duration of a measurement.
In the operating modes "Search" and "Ratemeter", measure-
ments are carried out to find contamination. In this mode, the
display quickly follows a change of the radiation field. In the
search mode, a lower measurement accuracy is accepted in
order to detect changes even faster.
An accurate measurement requires – in contrast to the search
mode – averaging of the count rates over an extended period of
time. The LB 134 is able to do this automatically in the rateme-
ter mode, provided that the average count rate remains within
the statistical significance all the time during this period. This
can be taken for granted, for example, when measuring contamination and the unit is not moved as long as the measurement is running.
However, in order to perform stationary measurements with a
given accuracy for the mean value, you should select the operating mode Counter-Timer. In this measuring mode, either the
averaging time or the statistical accuracy of the measured value
can be selected.
1.7 Important Measuring Parameters at a Glance
Alarm thresholds Alarm thresholds can be set for each measurement type and for
each nuclide; exceeding of these thresholds is signaled visually
and audibly. Moreover, in this case the measured value flashes
every second. An integral threshold can also be set for the integral value or dose value; exceeding of this threshold is signaled
visually and audibly.
Calibration factors Contamination monitors include two calibration factors for each
nuclide, since the detectors can be calibrated in accordance
with two different standards (DIN 25415 und DIN ISO 7503
Norm). When purchasing the device, the supervisor determines
the standard according to which the measurements are to be
carried out and selects the appropriate standard in the corresponding menu. For all other probes there is only a single calibration factor for the nuclides or for measurement types. If a
probe cannot be calibrated, we only get raw data and the calibration factor is then 1 for the unit cps or 60 for the unit cpm.
The calibration factor is multiplied by the net count rate to obtain the desired unit of measurement.
LB 134 Design and Mode of Operation of the LB134
11
Units Each nuclide and each measurement type (see above) has one
unit for the measured value and one unit for the integral or dose
value. The units consist of strings of up to 6 characters; they
can be entered from the keyboard or like any other parameter
via the USB interface. These units appear on the display behind
the respective measurement results and also with the stored or
transmitted data. Examples: Bq, pCi, Bq/cm², µSv/h, mrem/h,
etc.
Integral calculation time During the measurement, the current integral value or the dose
and the integration time elapsed until then is determined every
second by addition. If you have selected the unit counts per
second (cps), you get counts through adding up (counts). If you
have selected the unit µSv/h, as for the dose rate, then the time
base is not second but hour. Therefore, before the addition, the
value must be divided by 3600, since every second is added
up. When entering the integral calculation time or the time base,
this divisor is selected correctly. You can choose between seconds, minutes or hours.
Measuring range limits There is an upper measuring range value for each channel.
OVR appears on the display if this value is exceeded. In this
case, the integral calculation (dose) and the integral time will be
stopped. The upper limits are determined and set by the manufacturer. When working with ZnS scintillator for contamination
measurements, please keep in mind a special feature because
of the method used. Since alphas cause quite a bit of afterglow
in the scintillator, the beta channel is blocked for about 1.3 ms
when an alpha event occurs. Therefore, the message "Beta invalid" appears in the beta channel if the alpha rate is greater
than 750 cps. The upper limit for the alpha channel is nevertheless 5,000 cps, for the beta channel 50,000 cps.
Fail threshold Each detector has its own fail threshold and fail time because
the backgrounds are very different and we do not want to get
any false alarms, but on the other hand, we would like to get
failure messages as quickly as possible. In contamination
probes, failure monitoring always refers to the beta channel. A
counter/timer measurement monitoring whether the probe count
rate has fallen below the fail threshold is constantly running in
the background during a normal measurement. This test is carried out at the end of the fail time and, where appropriate, the
error message "Fail" is output. Then, this measurement will start
new. Please proceed as follows to determine fail threshold and
fail time. Basically, you want a failure to be indicated as early as
possible and you choose a small fail time. However, this largely
depends on the background rate of the detector. If this background rate is very small, you have to adjust the fail time. When
determining the two parameters, it is assumed that the background rate of the detector is Gaussian distributed. To get no
LB 134 Design and Mode of Operation of the LB134
12
false alarms, if possible, you need to set the threshold so low
that with the selected measurement time the threshold is, for
example, 6 standard deviations below the mean background
value. Then the probability that the background rate at the end
of the fail time is lower is less than 1.0E-06 and then there is vir-
tually no false alarm.
Example:
Background Ro = 0.5 cps; set measuring time Ta = 600 s; then
it holds for standard deviation S:
=0.029 cps
6 standard deviations = 0.173 cps
Fail threshold = Ro – 6 · S = 0.33 cps
At Ta = 300 s, the fail threshold would be 0.255 cps.
If you get a negative fail threshold, you have to increase the fail
time. However, you can always increase the number of stand-
ard deviations to be quite sure that you do not get any false
alarms.
Dead time Each detector has its own dead time which depends on the de-
tector properties and the subsequent amplifier and discriminator
electronics. With gas-filled counter tubes and NaI crystals this is
typically 1 to 3 µs. The effect of the dead time is that count rates
with increasing size do not increase linearly any more at some
point, but go into saturation. This effect is corrected to a certain
degree by the dead-time correction and the curve is linearized
again. The dead times for the individual detectors are deter-
mined and preset at the factory.
The formula used is:
Rcorr = Rmeas / ( 1 – tau * Rmeas)
Where
Rmeas: measured count rate in cps
Tau: Dead time in s
Rcorr: dead-time corrected count rate
Alpha only / Beta only mode Three modes can be used in a detector with simultaneous al-
pha/beta measurement:
Alpha/Beta simultaneously
Only alpha device
Only beta device
If you select alpha only or beta only, the device behaves as if it
is measuring only alphas or only betas. The results of the other
type of radiation appear never and nowhere. With simultaneous
LB 134 Design and Mode of Operation of the LB134
13
alpha/beta measurement one can select the view in three vari-
ants: Alpha and beta values as large display, alpha values large
and beta values on the info bar, beta values large and alpha
values on the info bar.
Store measured values Up to 2,400 individual measured values can be stored and
transferred to a PC or a memory stick via USB interface. The
important parameters are saved with the stored values. This
depends on the measurement mode.
The memory can be used as a memory with fixed length or as a
FIFO. With FIFO there is a write and a read pointer. If FIFO is
full, everything starts again from scratch and the oldest value is
overwritten. The FIFO can be read out and edited via the USB
interface using special commands. In a fixed-length memory
storing ends when it is full and an error message is displayed; a
status bit is set.
The following data is stored for each measurement: Date/time,
status, measuring time, measured value 1 (alpha), measured
value 2 (beta), unit, integral value 1, integral value 2, unit inte-
gral value, integral time (h).
The status includes: Probe type, detector failure, alarm 1, alarm
2, integral alarm 1, integral alarm 2, measurement active, FIFO
75% full, memory full, measuring range OVR1, measuring
range OVR2, beta channel invalid. A total of 12 ASCII HEX
characters.
LB 134 2. System Description
14
2. System Description
2.1 Enclosure with Electronics Module
The splash-proof enclosure contains the measurement and
control electronics, the internal dose rate probe LB 1346, the
software and the control elements of the monitor (see Figure
2.1).
Figure 2.1: Basic unit LB 134
Electronics The complete electronics with integrated dose rate probe
LB 1346 (including software and high-voltage generation) is lo-
cated inside the case. The connections for external components
are on the left and right. At the bottom, there are two contacts to
charge the batteries when the unit is placed in the wall bracket.
The internal dose rate probe LB 1346 is mounted on top behind
a bulge in the case.
LB 134 2. System Description
15
Figure 2.2: Position of internal dose rate probe
Connections The connections for the power supply unit (PSU), the head-
phones (jack plug), relay connection for the external signal
lamp and RS485 communication are located on the left side of
the device. USB host and device connections and the Fischer
connector for the external probes are located on the right side.
Headphones PSU Relays and RS485
Figure 2.3a: Left side of LB 134 with connections
LB 134 2. System Description
16
Probe USB – Device USB - Host
Figure 2.3b: Right side of LB 134 with connections
Operating voltage The device can either be operated via power supply unit
(PSU) (6 V), via rechargeable batteries (4x Mignon 1.2 V) or
via batteries (4x Mignon 1.5V), located at the bottom of the de-
vice (see Figure 2.4). If the PSU is connected, the operating
voltage is supplied through the line voltage and the rechargea-
ble batteries can be charged. The charging process starts au-
tomatically. During charging, the device is mains powered.
If the LB 134 is connected directly to mains or to the charg-
ing station, the unit turns on automatically.
Battery compartment cover Contacts wall holder
Figure 2.4: LB 134 (rear view)
LB 134 2. System Description
17
2.2 Operating and Display Elements
Measurement, operation and display are controlled by the soft-
ware integrated in the LB 134. Results, menus and user infor-
mation are displayed on a monochrome LCD graphics module
(192 x 64 pixel) with LED backlight and scratch-resistant Plexi-
glas. The device is operated by means of six function keys be-
low the display. Alarm and status signals are output via two
LEDs and a buzzer.
2.2.1 Design of the Display
Measurement menu
Top line (black background):
Measurement mode and probe name are displayed in the top
line.
Center panel:
Net measured value(s), with unit of measurement and meas-
urement nuclide(s)/measurement type or net (= cps measure-
ment). With simultaneous / measurement, both measured
values are displayed. Below that, information on the measure-
ment is displayed which can be selected via the Info softkey:
e.g. gross values or display as Scale from 0-100% relative to
the alarm threshold of the selected nuclide and many more.
Figure 2.5: Display and function keys
Bottom line (black background):
Displays menus and functions that can be selected via the but-
tons below the display (so-called softkeys). The top four func-
tion buttons have the function assigned to them by the softkeys
located directly above each button.
Measurement mode
Measured value
Info line
Softkeys (menu)
Function keys
LB 134 2. System Description
18
System menu On the System menu the menus and functions are displayed
for selection, and parameters can be edited.
The selection and parameter input takes place via the push but-
tons. The bottom line of the display shows the function of the
push buttons.
Figure 2.6: Softkeys directly below the display
2.2.2 Function keys and their meaning
The device and software is operated using six push buttons,
two of which are labeled with their function name. In the Meas-
urement menu, the top four buttons have the function assigned
to them by the softkey located directly above each button. The
softkeys are displayed in the bottom line of the display (in
black).
2.2.3 Warning Signals
LED indicators The LEDs on the membrane keypad indicate the following
states:
Top LED Alarm when threshold is exceeded
Bottom LED After pressing a button the LED lights up as long as the proces-
sor is busy processing the triggered function.
Acoustic signal When the threshold is exceeded, a warning signal is output
(provided this has been set in the Parameters menu). The red
LED (top) is flashing. In the Parameters menu you can choose
Visual or Audible as signal type.
Battery change If the battery/rechargeable battery voltage displayed after power
on is below 4 V for battery operation and below 4.5 V for re-
LB 134 2. System Description
19
chargeable battery operation, the remaining battery life is 2-4
hours max.!
In this case, the batteries need to be replaced.
2.3 Power Supply
Remove the battery cover by pulling it downward.
Figure 2.7: Open battery compartment
The device can be operated with 4 batteries or (Mignon 1.5V)
rechargeable batteries (Mignon 1.2V).
The polarity of the batteries is indicated at the bottom of the bat-
tery compartment (see. Figure 2.7).
Whenever you turn on the device, you will be informed about
the status of the batteries: The voltage can be viewed on the
menu Parameter/Power supply.
Note:
The RAM which stores the measured values, settings and the
date is regularly supplied with power by a lithium backup battery
when the device is not powered via the mains or batter-
ies/rechargeable batteries. In order to avoid loss of data, we
recommend replacing the lithium battery while the unit is pow-
ered via the mains or batteries/rechargeable batteries. The lithi-
um battery is located on the motherboard and should be re-
placed only by trained personnel.
LB 134 2. System Description
20
2.3.1 Working with Batteries
If batteries are used as power supply, you must select Battery
in the Parameter/Power Supply menu. With this setting, the
Charge function is disabled.
2.3.2 Working with Rechargeable Batteries and PSU
If rechargeable batteries are used as power supply, you have to
select Accu in the Parameter/Power Supply menu. With this
setting, the Charge function is enabled when the charging
mode is set to ON (indicated by an X in the square box).
Do not enable the charge function while batteries are in the
device.
The device turns on automatically when the LB134 is con-
nected to mains, directly or through the wall holder. The
charging process restarts depending on the settings in Cell
Type, Charge Mode and Charge Time:
The charging process only takes place when the device is
switched on.
2.3.3 Power Supply for External Probes
Batteries or rechargeable batteries supply power to the basic
unit and also to the external probes (5 V). The high voltage in
the probes is adjusted internally in the probes, but may also be
set using the control voltage (see below). The default setting for
the control voltage is 2.5 V.
2.3.4 Power Supply and Program Memory
1. The software program, the factory-set calibration factors and
any fixed settings are stored in FLASH and are independent
of the power supply.
2. The user-defined calibration factors, threshold settings, date,
measured values, etc. are stored in RAM (Li-batterybuffered). Using the Reset function (factory settings under
Parameters/Factory setting), these values can be deleted, in
which case the factory-defined settings are loaded. This
function is available only when the appropriate privileges
have been assigned.
LB 134 2. System Description
21
2.4 Data Interface
The LB 134 has two USB ports, a USB host and a USB device
interface with the appropriate connectors. However, both cannot be used simultaneously. A memory stick can be connected
to the USB host interface, and a PC to the device interface. Parameters can be uploaded and downloaded, currently measured data or the entire memory contents can be transferred to
PC and various measurement functions can be executed using
a PC program. The program creates different graphics and archives measured data or parameter files. The complete measurement data memory can be transferred or parameters can be
uploaded to and downloaded from the memory stick.
Furthermore, an RS485 interface is available, allowing integra-
tion of the device into a local network. Up to 32 measuring devices including central computer can be integrated in this network with a cable length of up to 1000 m. The baud rate to be
set depends on the cable length and the number of connected
devices. The standard cable used is a shielded twisted pair data cable which has to be terminated at each end of the bus between both wires with 120 ohms. The cable shielding is connected to ground at the central station of the network. The
shielding may also be connected to device ground at the individual measuring stations with LB 134, as long as they are operated with the power supply units provided, as these do not
have any connection to the local ground (no protective earth
connection) and thus cannot produce any undesirable ground
potential differences.
The F²C protocol, which is also implemented in some other BT
devices, is used for serial data communication via USB or the
RS485 interface.
The baud rate for the USB interface is always constant at
38,400 baud and cannot be changed; for the RS485 interface it
can be selected between 2,400 and 38,400 baud. (Menu Parameter/Hardware). The other parameters are fixed: data bits:
8; parity: none; start bit: 1, stop bit 1, no handshake.
At the end of each cycle, if selected, the following data is written
to a memory (read-only memory or FIFO):
LB 134 2. System Description
22
Date/Time: (6 bytes)
(Memory number: is sent with F2C)
Cycle number: 1...2000 (ushort) (2 bytes)
Status: 12 characters, ASCII Hex (12 bytes)
Sample measurement time [sec]: 1... 9999 (ushort) (2 bytes)
Nuclide name / Measurement type name 1: Text [7] (8 bytes)
Measured value 1: float (4 bytes)
Unit 1: Text [6] (7 bytes)
Integral value 1: float (4 bytes)
Integral unit 1: Text [6] (7 bytes)
Accuracy 1: Float (4 bytes)
Nuclide name 2: Text [7] (8 bytes)
Measured value 2: float (4 bytes)
Unit 2: Text [6] (7 bytes)
Integral value 2: float (4 bytes)
Integral unit 2: Text [6] (7 bytes)
Accuracy 2: Float (4 bytes)
Integral time since last reset [h]: float (4 bytes)
Required disk space per record: (94 bytes)
The depth of the FIFO is 2400 measured data. With Read
FIFO, the above data are transferred in this order after sending
the header data (frame).
The current status of the measuring device is determined every
second. This includes the states of all errors and alarms. This
information is summarized in 12 Ascii hex characters, with each
bit corresponding to a particular state.
These 12 characters are transmitted with the Get status command and with Store automatically each current measurement
time is saved to memory.
On request, the communication protocol can be supplied with a
command list.
2.5 Scope of Delivery
Basic equipment Measurement and display unit LB 134 with integrated dose rate
probe LB 1346.
Standard accessories 1 set of Ni/MH rechargeable batteries (Mignon (AA) 1.2V/2.5Ah)
1 power supply unit (PSU)
1 bag with strap
User manual
Optional accessories wall bracket for LB 134 basic unit (incl. screws and dowels)
Wall bracket for LB 1343 contamination probe
Different probes for the desired measurement tasks
LB 134 2. System Description
23
2.6 Wall Bracket (Optional Accessories)
The optional wall holder bracket is used as
Charging station (only with rechargable battery operation).
The LB 134 turns on automatically when the PSU is connected to the wall bracket and to mains. The charging process takes place only when the unit is (still) turned on and
when Accu is set as Cell type in the menu Parame-
ter/Power Supply!
Stationary application. The wall bracket is designed such
that the monitor is about 3 cm from the wall. Measurements
can be carried out in the battery or rechargeable battery
mode. We recommend working with the device with rechargeable batteries and the PSU connected (see charging
station).
Scope of delivery The delivery comprises the wall bracket and one set of dowels
and screws 4 mm in diameter. These dowels and screws
should be adequate for most walls. Other dowels/screws may
have to be used depending on the type of wall. The spacing of
the drilled holes for fixing the wall bracket is 85 mm.
Wall bracket (with mounting holes 5 mm in diameter)
Charging contacts PSU connector
Figure 2.8: Wall bracket
LB 134 2. System Description
24
Figure 2.9: LB 134 with wall bracket
LB 134 3. Commissioning
25
3. Commissioning
3.1 Connecting the Device
Unpack the device carefully.
Supply the device with power. The device can be operated
with batteries (Mignon 1.5V) or rechargeable batteries (Mignon 1.2V) or PSU (ID58067):
Battery or rechargeable battery operation: Remove the bat-
tery compartment cover by pushing it down. Insert the batteries into the battery compartment as indicated at the bottom of battery compartment. See Figure 2.7.
Mains operation: Plug the power supply cord on the left side
of the device into the corresponding jack, and secure it with
the screw cap. Plug the power adapter into the power out-
let. The device will be switched on automatically.
If the detector LB 1342 or LB 1343 is supplied, remove the
transport protection for the entrance window of the detector
on the device bottom by pushing out the black metal plate.
Keep the plate and always use it to protect the window foil
against damage during transport.
Press the On/Off button in the bottom left corner to turn on
the unit.
After power on, the device shows the software version, battery/rechargeable battery voltage, free memory space and
the date for 3 seconds, then changes directly in the ratemeter or counter-timer mode and is ready for operation immediately. Depending on the connected probe, the measured
value or the measured values of the measuring channel or
both channels (beta-gamma and alpha channel) are displayed.
Figure 3.1: Measured value display of the internal dose rate probe af-
ter power on
LB 134 3. Commissioning
26
3.2 The First Control Measurement
If you do not want to measure with the internal dose rate
probe, connect the desired external probe first to the device
using the spiral cable. Press the ON/OFF button to turn on
the unit. After power on, the device shows the software version and the battery/rechargeable battery voltage and then
automatically switches to the measurement mode. The LB
number of the probe is displayed in the top row. If this is not
the same as the LB number of the probe, this means that the
internal probe is selected. In this case, please enter the
menu by pressing the menu button:
If the checkbox in the top right corner is ticked, this means
that the internal dose rate probe is used, even when the external probe is connected. As the cursor (left arrow) is already in this line, you can disable the internal probe by
pressing Enter; then the external probe will be used (the X is
removed). Press ESC to go to the Measurement menu. Now
you can run measurements with the external probe.
If you want to test the functionality of the device first, you
can do this using the test source, you are also using otherwise, in the same geometry in front of the detector and compare the displayed value with the target value that you have
obtained during the first commissioning. Depending on the
probe used, you have to position the respective test source
accordingly, as otherwise the measurement result is not correct.
When working with the LB 1342, slide the metal plate with
the test source Sr-90 in front of the detector.
After about 10 seconds measurement time, read the meas-
ured value and compare it with the value indicated on the
test source. Your reading should reach this value with a tolerance of +/- 20% after about 10 seconds.
LB 134 3. Commissioning
27
3.3 Basic Parameter Setup
Before starting any measurements, you have to define the most
important parameters and change the factory-set parameters
(alarm thresholds, background, etc.) to match your needs and
circumstances.
Check and/or change the following parameters:
Set the Language.
Enter Date/Time. Important for your documentation. Date
and time are stored with each measurement.
Define Meas. Parameters for the individual measurement
modes and measurement channels in the Measuring Set-
tings menu.
If necessary, define calibration factors for additional nu-
clides or nuclide mixes and adjust the nuclide-specific warning thresholds.
Nuclide or measurement type selection for the meas-
urement. In order to select the nuclides or types of measurement required for your needs during an on-going measurement directly you should select the relevant nuclides/types of measurement in the small nuclide table/measurement type table for the measurement menu.
Perform background measurement. The background is
subtracted for each measurement. The background should
match your ambient conditions and you should check and
update it occasionally (at least once a week). For dose rate
probes, there is a so-called intrinsic background, which is
determined under very special measuring conditions in the
factory (special and extensive shielding). This value must
not be changed.
To simplify handling, the device allows you to hide single or
all menus for the measurement operation. On the other
hand, the menus can be enabled only to View only the parameters or to View and change the parameters. The supervisor of the unit should carefully consider which menu
mode is suitable for his area of work. A password is required to enable the menu.
Upon delivery, the password is 0.
LB 134 3. Commissioning
28
3.4 Installation of Wall Bracket for Stationary Operation
For stationary operation, mount the wall bracket on
the wall using the supplied screws and wall plugs (at
about chest height).
Connect the PSU to the wall bracket and to mains.
We recommend using rechargeable batteries for this
application; select Accu in the Power Supply menu.
Set the Charge Mode to On (X).
Place the LB 134 in the wall bracket. The unit turns on
automatically.
If you are working with an external probe, this probe
must also be mounted on the wall in the vicinity of the
device and connected to the device with a coiled cable. For RS485 networking, connect the shielded
twisted pair data cable to the device using a 6-pin
Fischer connector. The last device and the first device
or data center at the ends of the bus cable must be
terminated with 120 ohms (either in the plug or a wiring box).
Now you are ready to perform stationary measurements – pro-
vided the appropriate device settings have been done.
LB 134 3. Commissioning
29
3.5 Possible Problems during Commissioning
The following errors or error messages may be encountered during commissioning:
Error (message)
Cause/Remedy
No message in display
Batteries are exhausted. Replace batteries.
No power supply. Check connection cable.
Target count rate of test sources
not reached
or
Background count rate is too low.
or
Displayed count rate is "0.0 CPS"
Correct detector and possibly check tightness:
o For scint detectors: If detector foil is defective and
light enters, the high voltage turns off, count rate
is zero. Then the device must be turned off.
o For gas-filled contamination detectors: If detector
is OK, the detector foil must be smooth, tense
and plane. A slack, wrinkly foil indicates that the
counter tube is
damaged. Please call Service!
Possibly, HV unit of detector is defective. Replace the detector if the HV unit is defective.
The set background is too high. To check this, push the
Info button to view the gross data.
Connection electronics <--> check probe
INV (only scint detector)
Count rate in alpha channel > 750 cps. Above this count
rate, no meaningful measurement is possible in the beta
channel.
OVF
Measured value above the measuring range
For scint detectors:
Count rate in alpha channel > 5000 cps or
Count rate in beta channel > 50 000 cps.
LB 134 4. Software Design and Operation
30
4. Software Design and Operation
4.1 Software Design
System menu The software of the LB 134 has a menu-based user interface.
All functions and parameter settings are selected from the Sys-
tem menu. The main menu items of an alpha-beta contamination probe are as follows (in a dose rate probe Nuclides is replaced by Meas. Types):
Figure 4.1: System menu for alpha-beta probe
Several dots (...) behind a menu item indicate that this function
leads to further displays.
For menu items showing a parameter setting (e.g. menu item
Meas. Mode), the setting can be changed directly by selecting
the respective menu item with the cursor () and pressing the
Enter key. You select an item with ↓↑ (left button) and change
the setting with the Enter key.
To select a menu or an option, move the cursor to the desired
menu item and then press the Enter key.
LB 134 4. Software Design and Operation
31
4.2 Measurement Menu Display
The Measurement menu appears
a) immediately after switching on the device or
b) by pressing ESC on the System menu.
We have chosen a dose rate measurement as an example.
If you press the double arrow key () on the right, further
functions appear in the bottom line.
If you press the double arrow key on the right once more, fur-
ther functions appear in the bottom line. If you press this key
once more, the first functions appear again (see first picture).
The functions are explained in detail.
Figure 4.2: Measurement menu of a doserate probe
In the measurement menu, the type of radiation is displayed
first that was set on leaving the measurement menu. In an alpha-beta contamination probe, you can then choose whether
both types of radiation are to be displayed at the same time or
what type of radiation (measuring channel) is to appear as the
main display. The other measuring channel is then displayed in
the info bar.
LB 134 4. Software Design and Operation
32
In the menu item Display Mode you can toggle between these
modes of display. You can select additional information to the
main display by briefly pressing the Info button in each of the
three modes of display. The three display options for alpha and
beta contamination show the following three displays.
Main display: - channel Main display: Both channels Main display -channel
Top line
of display
Indication of Measurement mode (ratemeter, counter/timer ...) and LB number of the
probe and Status (buzzer / light) and on the left the storage number at the time of saving
Second line
(only 1 channel)
2nd/3rd line
with 2 channels
Left: Nuclide or Measurement type or Net/Gross
Right: Radiation type
Radiation type, nuclide/measurement type, measured value, unit
(third line same as second line but only for channel 2)
Center
(one channel)
Net/gross results during the measurement (in [cps], [Bq/cm
2]
or µSv/h or according to the
selected nuclide(s) and/measurement type(s) or the computed unit of the measurement
Info line, second line
from the bottom
Scroll with Info
Measured value of the 2nd measuring channel, dose (integral value), bar graph, accuracy,
calibration factor, date and time, background with measurement time, minimum and maximum value, raw data value, net count rate, measuring time at N cycles, accuracy of the
mean, selectable by repeatedly pressing (briefly) the Info button
Bottom line
Display of softkey function relative to the selected mode.
Counter/Timer: During measurement: Info, Stop, Graph
After the measurement: Nuclide, Start, Menu, Info, Mode,
Save, Graph, Start, Integral
Ratemeter: During measurement: Nuclide, Save, Menu, Info, Mode,
Graph, Reset, Integral start
Search: During measurement: same as Ratemeter
During the measurement, the Nuclide/Measurement type stored in the small nuclide library can be selected by repeatedly pressing the Nuclide/Measurement type
button (separately for each type of radiation).
LB 134 4. Software Design and Operation
33
Info button Press this button repeatedly and briefly to display additional in-
formation on the ongoing measurement. Even after measurement end, further information is available for counter-timer and
background measurement measurements.
Depending on the measurement mode, the following additional
information is displayed:
Main display: - channel
Additional display of the measured value of
the 2nd channel (here alpha channel)
% Scale. This bar graph shows the ratio of
the respective measured value to the set
threshold value. Expressed as a percentage
of the threshold value. If the threshold is exceeded, the top LED flashes and an alarm is
triggered – if preset. The multiplication factor
is indicated next to the graph: x10; x100;
x1000.
Accuracy of 1st measuring channel
Threshold value and calibration factor of
the 1st measuring channel
Cycle X of N, measuring time, preset
measuring time
Background that is subtracted
Minimum and maximum value of the cur-
rent measurement in the 1st/2nd channel.
Gross measured value
Mean value over N cycles, total measurement time, MV accuracy also available
Main display: - channel
LB 134 4. Software Design and Operation
34
4.3 Key Functions
A long keystroke is identified by a double tone and by a brief
flashing of the lower LED. Then you can release the button.
The software is operated using the 4 push buttons in the mid-
dle, below the display. They have the following functions:
In the Measurement menu and during measurements, soft-
keys (menu options) are displayed in the bottom line of the display which assign their respective function to the button located
directly below the softkey. Push the button to select that option.
4.3.1 Labeled Push Buttons and their Function
The label on each key indicates the function of this key.
Turning on/off the device.
Push this button for about 0.5 seconds to power on, and for at
least 1 second to power off.
Turning on/off the buzzer and the LCD backlight and adjusting the display contrast (keep button pushed until the
desired value is reached). The current status is displayed in
the top line of the display.
If the LCD backlight is turned on: The backlight turns off automatically if no button is pushed for 60 seconds. It is turned on
again automatically when a button is pushed.
4.3.2 Softkeys
The software is operated using so-called softkeys. Softkeys are
software-controlled key functions which assign the push buttons
their current functions on the display. They are shown in the
bottom line.
Line with softkeys
Figure 4.3: Softkeys and assigned functions
LB 134 4. Software Design and Operation
35
Explanation of the example in Figure 4.3:
Press the third button (Menu) to enter the System menu to se-
lect the individual menus.
Press the Meas. Type button repeatedly (if you are working
with contamination probes you will see Nuclides here instead)
to scroll through the small nuclide library/measurement type table and you can select the desired nuclide/measurement type of
the displayed type of radiation for the current measurement. If
the display does not switch to another nuclide/measurement
type when you press this button, this means that no further nuclide/measurement type has been defined.
Press the Save button to save the measurement.
Press the button to go to the next functional level (see
above).
4.4 Operation
4.4.1 Selecting Menus and Options
On the System Menu, move the cursor () to the desired
menu or the option by pressing the ↓↑ key and then press En-
ter. The relevant menu item is enabled and the associated
page is displayed.
4.4.2 Editing: Entering Numbers and Letters
Move the cursor () to the desired parameter by pressing
the ↓↑ key and then press Enter. This enables the editing
mode for the respective parameter and the first digit is
marked by the cursor .
Figure 4.4: Selecting a parameter
Start typing here to make a new entry. To overwrite an exist-
ing digit, move the cursor to the desired digit.
Now select the desired number by repeatedly pressing the
↓↑ key.
To enter the second place, press the button and then
select the desired number by repeatedly pressing the ↓↑ key.
LB 134 4. Software Design and Operation
36
Proceed in the same manner with all digits of the desired
number.
Once all digits of the desired number have been entered,
press Enter to confirm.
Letters are entered in the same way (01234567890abc...z).
4.4.3 Selecting Items from a List
If you can only select predefined values or categories from a
list, proceed as follows:
Select the parameter with the cursor.
Press the Enter key. The editing mode is enabled. Repeated
press the ↓↑ to view the available options one after the other.
Select the desired option with Enter. The selection is ac-
cepted.
Examples:
Setting the Measurement Mode
Ratemeter
Counter-Timer
Search
Measurement settings for ratemeter measurements:
Averaging criterion
Time constant or
Accuracy
4.4.4 How to Access the System Menu
After power on
After power on, the device automatically goes into the
measuring mode which was set when the device was turned
off (Measurement menu).
In the Ratemeter mode: Select the Menu option by pressing
the Menu key. You get into the System Menu.
In the Counter-Timer mode: Stop the running measurement
by pressing Stop. The Menu softkey appears. Then press
the Menu button.
LB 134 4. Software Design and Operation
37
During parameter input
Quit the edit mode by pressing Enter or Esc.
Press Esc once more. This will bring you to the one next
menu in the menu tree until you get to the System Menu.
Figure 4.5: System menu with menu items
4.4.5 LED Indicators
The two LEDs on the membrane keypad indicate different
states:
Top LED: Alarm when the threshold is exceeded.
Bottom LED: When you press a button for a longer time then
this LED goes on for a very short moment to indicate that you can release the button. This is
used to move the cursor backward in a menu.
LB 134 5. Contamination Measurements
38
5. Contamination Measurements
In this chapter we will discuss the contamination measurement,
which is representative of the performance of other measurements. Other measurements, for example, activity measurements of samples or dose rate measurements, are very similar,
but they still differ in some respects. Contamination and activity
measurements usually deal with specific nuclides or nuclide
mixes, whereas we usually do not know the nuclides in a dose
rate measurement. Selectable measurement types were therefore introduced instead of nuclides to quickly switch between
different units (e.g. µSv/h and mrem/h). In all cases, you can
use the ratemeter function or the counter timer function, depending on accuracy considerations. Sample measurements,
however, should essentially be performed using the counter
timer function. You can also calculate the integral over the
measurement unit in all types of measurement, which is of major importance in dose rate measurements for the calculation of
the dose. In contamination measurements, one can determine
the counts for a given period from the cps values through integration by selecting Net.
We will now take a closer look at a contamination meas-
urement.
Contamination measurements can be performed immediately
after starting up the device and in conjunction with an external
contamination probe. After power on, the device starts a measurement immediately and displays the results for the preset nuclide and measurement mode or for the background measurement (if the autostart function has been enabled).
Please note that the following three operations have to be per-
formed as a prerequisite for adequate contamination measurements:
1. After commissioning of the monitor and later at regular intervals, you have to perform a functional check and verify the
correct operation of the device. This is also required by § 67
of the Radiation Protection Ordinance (in Germany).
2. Usually, we first measure the ambient radiation caused by
the activities (= background) to obtain the pure surface radiation. The stored background is subtracted automatically
from all measurements.
3. Nuclide-specific alarm thresholds are entered for the radiation to be measured; audible and visual alarms are triggered
when these thresholds are exceeded.
LB 134 5. Contamination Measurements
39
5.1 Requirements for Contamination Measurements
5.1.1 Function Check
Turn the device on and make sure sufficient battery capacity is
available.
Warnings:
If the battery/rechargeable battery voltage displayed after
power on is below 4V for battery operation and below 4.5 V
for rechargeable battery operation, the remaining battery life
is 2-4 hours max.!
Eliminate this problem prior to measurement!
Slide the plate with the test source on the detector and read
the measured value after about 10 seconds. After this time,
a sufficient measuring accuracy is reached. You can also
use the System Test function of the PC program. You can
check if the measured value coincides with a target value
within a given limit.
Compare the measured value with the target value that is
specified on the test source for each detector type and the
selected source type. The device is working properly only if
your measured value is within the specified range of variation.
5.1.2 Measuring and Saving the Background
The background, the environmental radiation, is measured in
cps. It is automatically subtracted from sample measurements.
Gross and net values can be displayed on the screen.
Proceed as follows
Select Background on the System Menu. The background
parameters and the start option will be displayed.
LB 134 5. Contamination Measurements
40
Figure 4.6: Background menu for contamination probe
Set the desired parameters for the background measure-
ment.
Background: Shows the currently stored -
background. It may come from a background measurement or it can be entered
manually. The stored background is always subtracted from each measurement.
Background: Shows the currently stored
background. It may come from a
background measurement or it can be
entered manually. The stored background is always subtracted from each
measurement.
Meas. Time: Enter the desired measuring time. Enter
at least 60 seconds, better 600 seconds
in order to get accurate results.
Autostart: When ON is set (X mark), a background
measurement is carried out automatically
whenever the device is turned on.
BG Meas. Time: If a background measurement was car-
ried out, the elapsed background measurement time is entered here after saving. On the other hand, if you have entered the background by hand, you have
to enter the measuring time associated
with the background, so that the accuracy calculation is correct for a contamination measurement.
Start the background measurement by moving the cursor
() to Measure background and press the Enter key.
Then the background measurement starts.
Figure 4.7: Background measurement
The measured values and the elapsed measuring time are
displayed continuously. At the end of the measuring time,
LB 134 5. Contamination Measurements
41
the background measured for both measuring channels is
displayed.
End of the background measurement: When the preset
measuring time is over or by pressing the Stop button. The
following softkeys are now enabled: Save the background,
Start a new background measurement, back to the system
Menu and Info.
Figure 4.8: Display at the end of a background measurement
Select the Save option by pressing the Save button The
stored background is displayed on the menu next to
background and background (see Figure 4.6).
The background should be measured daily or occasionally
or it should be measured new and stored whenever changing the environment to avoid incorrect results!
Automatic background measurement
With the autostart function enabled, a background measure-
ment is carried out with the preset parameters whenever the
device is turned on.
At the end of the background measurement (measuring time is
over or stop) the value determined can be stored via the Save
button or a new background measurement can be started with
Start.
LB 134 5. Contamination Measurements
42
Procedure Automatic background measurement after power on of the
device.
BG measurement finished (at the end of measurement or by
pressing Stop)
Saving the BG values
Figure 4.9: Display at the end of a background measurement
Press ESC twice to start the contamination measurement.
Figure 4.10: Return to the measurement menu
5.1.3 Creating the Small Nuclide Table
To be able to select particular nuclides for a sample measure-
ment, you first have to select those nuclides from the nuclide
table that you use most frequently and that you wish to access
directly during measurements. These nuclides are stored in a
small nuclide table to which you have direct access during each
measurement via the Nuclides softkey. The scope of the small
nuclide table is adjustable (minimum: net; maximum: all nuclides). This allows you to switch to another nuclide at any time.
Upon delivery, the small nuclide table already includes several
nuclides.
At the same time, you can enter Alarm Thresholds for these
nuclides; when they are exceeded, an alarm signal is output.
LB 134 5. Contamination Measurements
43
If the nuclide or nuclide mix to be measured is not yet included
in the small nuclide table, proceed as follows
Select Nuclides on the System Menu.
Figure 4.11: System menu
Press the Enter key. The nuclide table is displayed. The nu-
clides contained in the small nuclide table are marked with
an X.
Figure 4.12: Nuclide table. Pre-selected nuclides are
marked by an X.
Move the cursor to the nuclide you wish to include in the
small nuclide table using the ↓↑ key, and then press the
key to go to the next function level. Now press the Edit button. A new menu will appear listing all nuclide parameters:
Name, Active, Radiation Type, Mass Number, Unit, Cal.
Factor A-100 (according to DIN 25415), Cal. Factor ISO
(according to DIN ISO 7503-1), Alarm Threshold, Integral
Threshold, Integral Unit and Time Base. Now move the
cursor to Active to select the nuclide with Enter.
Press ESC twice to quit the nuclide table. You get into the
System Menu.
LB 134 5. Contamination Measurements
44
5.1.4 Importance and Editing the Other Nuclide Parameters
In addition to the activation of a nuclide, there are the following
parameters:
Figure 4.13: The parameters of a nuclide
Edit procedure
Move the cursor (->) to the desired menu item.
Press the Enter key.
A list of options or the field for parameter input appears (see
above).
Enter the desired value, or select an entry from the list.
Confirm your entry by pressing the Enter key.
Meaning of the parameters
Name: Name of nuclide
Active: Select nuclide for selection prior to a
measurement (small nuclide list)
Radiation Type: Alpha, beta/gamma, gamma, neutron
Mass Number: Mass number from the nuclide table
Unit: Physical unit
Cal. Factor A-100 Calibration factor according to
DIN 25415
LB 134 5. Contamination Measurements
45
Cal. Factor ISO Calibration factor according to
DIN ISO 7503-1
Alarm Threshold: Alarm threshold for visual and audible
alarm in the same unit as above
Integral Threshold: Threshold for the integral value of the
measurement unit
Integral Unit: Unit of the integral value
Time Base: Used for calculating the integral, for
“s” the measurement value is added
linearly every second, for “min” each
measured value is first divided by 60
and then added, for “h” each meas-
ured value is first divided by 3600 and
then added (e.g. for µSv/h)
5.2 Measurement of Contaminations
Two types of measurement are available for surface contamina-
tion measurements:
1. Measurement of the net count rate in CPS (counts per second).
2. Measurement of the net activities per area with the unit
Bq/cm²; the nuclide or nuclide mix to be measured has to be
set.
Both types of measurement can be selected in the Ratemeter,
the Search or the Counter-Timer measurement mode.
The measuring channel (, or and ) is selected on the
System menu under the menu item Display Mode. The nuclide
are set in the Measurement menu by repeatedly pressing the
Nuclides key. In the and mode, however, a new softkey
group appears with separate keys for the alpha and beta channel, which allows separate nuclide selection. You pass through
the nuclides selected from the nuclide table (small nuclide table) and the measurement mode Gross and Net [cps] in cyclical order. The selected nuclide is displayed in the top left corner
of the display. When passing through the small nuclide table
only the nuclides of the set measuring channel (type of radiation
or ) are displayed: So, if only the channel is set on the
Measurement menu, only nuclides are displayed when you
are going through the small nuclide table.
From the nuclide table you select those nuclides you need most
often (e.g. Net [cps], -tot, C-14, etc.).
By pressing the Nuclides button one can switch directly from
this preliminary selection during the measurement.
LB 134 5. Contamination Measurements
46
Each display shows the currently measured value, the unit of
measurement and, on the left, the selected nuclide and the
measurement mode. The measured value for the new setting is
displayed virtually with no time delay whenever there is a
change in display. In the counter/timer mode, the measurement
must first be stopped for a nuclide change.
The detector has to be held as closely as possible to the sur-
face to be measured (be careful not to damage the foil!). Depending on the level of the count rate, in the counter/timer
mode a different measurement duration and in the ratemeter
mode a different time constant or preset accuracy has to be
used to obtain a fairly low statistical error. Decreasing statistical
fluctuations become apparent from the fact that the displayed
measured values show less and less deviations. The stored
background rate is automatically subtracted.
5.2.1 CPS Measurement
Start the measurement by selecting the desired measurement
mode (Ratemeter, Counter/Timer ...) on the System Menu
and then press ESC to go to the measurement menu.
If gross or net [cps] is not yet set, select this setting from the
small nuclide table. Press the Nuclides button repeatedly until
Gross or Net is displayed in the second row of the display (see
below).
Display Net
2nd measuring channel
Figure 4.14: CPS measurement
Press the Info softkey to view further information on the ongo-
ing measurement.
5.2.2 Measurement of Area Activities
Start the measurement by selecting the desired measurement
mode (Ratemeter, Counter/Timer ...) on the System Menu
and then press ESC to go to the measurement menu.
LB 134 5. Contamination Measurements
47
In the Display Mode menu you can change the display lay-
out.
Then select the nuclide to be measured:
- If two measuring channels are displayed, press the
Nuclides key first. Then the function of the softkey
changes. Using the keys and you can now set the
and the nuclides separately.
Figure 4.15: Nuclide selection with simultaneous / measurement
In the selected measurement mode (Bq/cm²), the detected
count rates (cps) are converted to area activities (Bq/cm²) using
a calibration factor entered in the device. The previously saved
background rate is automatically subtracted, so that the net area activities are displayed here.
Press the Info softkey to view further information on the ongoing measurement. The Graph function allows you to present
the change of the measured value over time graphically. The
graph runs from right to left and you always see the values of
the last 120 seconds. With Delete the graph can be reset and it
starts all over again. In the counter/timer mode we get a new
pixel in the graph for each elapsed cycle.
Figure 4.16: Change in the -values over time displayed as a
graph
LB 134 5. Contamination Measurements
48
5.2.3 Explanations on Raw Data and Calculated Units
In this chapter you will learn to choose the appropriate meas-
urement mode for each situation, and what differences there
are between the individual modes:
Net [cps] Net - counts per second
In this measurement mode, the net count rate coming from the
detector is displayed, provided that a stored background is
available. In addition, the gross count rate can also be displayed.
This measurement mode is always used to determine a general
change of the degree of contamination or the radiation level or if
you do not know which nuclide contains the contamination.
Bq/cm² Area activities
In this and the following measurement mode, the detector count
rates (cps) are converted into area activities using a calibration
factor stored in the device (Bq/cm²). The stored background
rate is automatically subtracted.
e.g. Beta sources (total) = β-tot
-tot means "Beta total". In this case, the conversion factor
does not refer to a specific radionuclide, e.g. iodine-131, but is
based on the average factor of a nuclide mix which can typically
be expected after a reactor accident.
This measurement mode is used
a) to check whether the limit values for surface contamination
stipulated in regulations or provisions have been exceeded,
and
b) the contamination has been caused by a recent power plant
accident and its composition is not known.
e.g. Cs-137 (or another nuclide)
In this measurement mode, the conversion factor is related to
the surface activity of a particular nuclide. The nuclide can be
retrieved from the built-in nuclide library.
This measurement mode is used
LB 134 5. Contamination Measurements
49
a) to check whether the limit values stipulated in regulations or
provisions have been exceeded, and
b) the contamination has been caused by a well-known radio-
nuclide.
If you are dealing with a mixture of radionuclides and you know
the individual nuclides, you can use a so-called reference nuclide which accounts for either the main portion of the mixture
or is particularly dangerous (with fresh fission products, this will
almost always be I-131).
Caution!
This measurement mode does not mean, however, that the
monitor is able to measure the contamination of a radionuclide in a mixture deliberately and selectively. It only evaluates the contamination as if it were caused by the respective radionuclide.
New nuclide It is possible to add new nuclides or nuclides that were not yet
entered to the nuclide list. Go to the Nuclides menu and select
Add. Then enter all parameters mentioned above, such as
name, calibration factors, thresholds, etc. The new nuclide must
be activated to view it in the small nuclide list.
This measurement mode is used
a) to measure a nuclide that is not included in the nuclide li-
brary. Prerequisite is the calibration of the device with an
appropriate calibration source, or
b) to measure a particular nuclide mix containing nuclides from
the nuclide library.
5.3 Measured Result as a Function of the Contaminated Surface
The calibration factors for the Bq/cm² display determined at the
factory and stored in the LB 134 in the setting A-100 (according
to DIN 25415) refer to calibration sources having the dimensions 10 cm x 10 cm and an activity certified by the German
Calibration Service respectively in the setting ISO 7503 (according to DIN ISO 7503-1) refer to the active detector area and
an surface emission rate certified by the German Calibration
Service.
Comparative measurements with other devices which also dis-
play in Bq/cm², therefore, will only lead to consistent results
when these devices were also calibrated with such sources. So
if you get other values from comparative measurements than
those displayed by LB 134, please check
LB 134 5. Contamination Measurements
50
a) whether the same radionuclide has been set, and
b) whether the source used for calibration meets the above
mentioned requirements.
When measuring area contaminations, the extent of the con-
tamination relative to the standardized area of the calibration
source of 100 cm² (in the setting A-100) also plays a role.
For measurements according to §44 of the Radiation Protection
Ordinance (Germany), the averaging area can be up to
300 cm². The measurement area of the probe LB 1342 is 118
mm x 145 mm (171 cm²) at a transmission of 80%. In the
LB 1343 probe the active measurement area is 345 cm².
For contaminations less than 100 cm² this averaging is done
automatically due to the aforementioned calibration conditions.
A contamination of, say, 10 Bq/cm², but an expansion of only 50
cm², is displayed as 5 Bq/cm² (distributed over 100 cm²) as a
result of this averaging.
However, if the extent of the contamination is greater than 100
cm², the monitor overevaluates: It shows at 10 Bq/cm², spread
over 150 cm², for example, 15 Bq/cm².
5.4 Exceeding of Limit Values
Any exceeding of user-defined limit values is indicated on the
display by a flashing measured value ( or ). Moreover, an
alarm signal is output (visual as flashing LED, audible as short
alarm beep), if preset (see System menu: Parameter->Alarm).
The alarm is displayed in any case, no matter which measurement mode you are in.
Figure 4.17: Exceeding of limit values
If the entrance window is defective (light enters the counting
chamber) and the count rate is exceeded for a short time, the
scintillation detector is turned off, i.e. the high voltage is turned
off. In this case, the entrance window must be replaced.
LB 134 6. Software Functions
51
6. Software Functions
In this chapter you will find information on all measurement
functions, parameters and service functions in the order they
appear on the System Menu. It starts with the description of the
actual measurement of contamination, activity or dose rate.
For a detailed description of the software operation please refer
to chapter 4 (how to select the System menu and menu items,
editing, etc.). You have access to all menu items from the Sys-
tem Menu. See also Table 6.1.
After start-up and configuration of the device, only those menu
items appear for which the user has read or edit rights. The user rights are password protected and can be changed only by
the device supervisor under the item Menus Enable. There, the
rights: Off, Read only and Read and Edit can be assigned. Off
means the menu does not appear in the menu list. Read only
means you can view the parameters but you cannot edit them.
Read and Edit means that you can also edit the parameters.
Next, we will describe the measurement function.
6.1 Measurement of Contamination, Activity or Doserate
After power-on or when you press the ESC key on the System
Menu, the Measurement menu appears and – in the Ratemeter
or Search mode – the measurement starts automatically in the
preset measurement mode using the selected parameters. In
the Counter/Timer mode, you have to press the Start button.
The active measurement mode, the LB number of the probe
and the current measurement results are displayed. Example in
the Ratemeter mode:
Press the double arrow key on the right to access more func-
tions in the bottom line.
LB 134 6. Software Functions
52
System Menu Options
Live Display
Measurement
Use Int. DR-Det.
OFF, ON
Background
Start Measuring
BG Alpha/
BG Beta-Gamma
Meas. Time
Autostart
OFF, ON
Meas. Mode
Ratemeter, Counter-Timer, Search
Meas. Parameters
Meas. Time
Cycles
Avg. Mode
Time Constant / Accuracy
Sigma Factor
Auto Save
Auto Send
Nuclides
Nuclide List ....
Name
Active Yes / No
Radiation Type
Mass Number
Unit, etc. ........
Integral Reset
Yes / No
Display Mode
α + β, α, β
Memory
Show Memory
Delete Memory
Memory USB Stick
Para USB Stick
USB Stick Para
Memory Mode
Finite memory or FIFO
System Test
Start Measuring
Parameter: Meas. Time, Nuclide, Ref. Value, Max. Dev.
Date/Time
Language
German / English
Device Addr.
1 to 255
Calib. Type
ISO 7503-1, A-100
Backlight
Dark, Medium, Bright
Headphones / Relay
Headphones or relays for alarm
Power Supply
Battery Type Battery or Accu
Charge Mode Yes / No
Charge Time in h
Line Volt. in V
Batt. Volt. in V
Hardware
Detector Type LB number
Ser. No. Det.
Ser. No. Device
Ctrl. Volt. for ext. Probe in V
Baud Rate 2400-38400 Baud
Key Sounds on / off
Serial ready yes / no
Vinculum Program. On / Off (only final test)
Dead Time α and β channel
Fail Time in s
Fail Thr. in cps
Detector Mode: α + β, only α, only β
Transmission α
Range upp. α and β channel
Factory Defaults
Yes / No
Alarm Type
Optical
OFF, ON
Acoustic
OFF, ON
Ticks
-Ticks
OFF, ON
-Ticks
OFF, ON
Enable Menus
Enter Password
Background
Meas. Mode
Meas. Parameters
Nuclides
Integral Reset
Display Mode
Memory
etc.
Table 6.1 All menus at a glance
LB 134 6. Software Functions
53
If you press the double arrow key on the right once more, further functions appear in the bottom line. If you press this key
once more, the first functions appear again (see first picture).
The functions are explained in detail.
Figure 6.1: Display in Ratemeter mode
Nuclide Select the desired nuclide or nuclides from the small nuclide ta-
ble depending on the selected measuring channel. (The contents of the small nuclide table is selected on the Nuclides
menu.) The nuclides can be selected during a measurement. If
you are working with dose rate probes, the Measurement
mode is displayed here and instead of nuclides you can select
preset measurement types.
Save Saves the measurement results of the stopped or completed
measurement in the Counter/Timer mode. In the Ratemeter
mode you can save the results any time.
Menu Go to the System Menu.
Mode Three functions can be selected:
Ratemeter, Counter/Timer and Search which are selected
here.
Graph Shows a graph of the measured values as a function of time. In
the Ratemeter mode the seconds values are recorded from
right to left. In the Counter/Timer mode, a dot is drawn from
right to left at the end of each measurement. 120 dots max. are
displayed.
LB 134 6. Software Functions
54
Reset This button resets the Ratemeter parameters, such as min/max
values, cycle storage time, smoothing filter parameters.
∫Start Starts the integral calculation, summing up of the measured
values; for dose rate it starts the dose calculation, start of the
integral time. If the integration was stopped before, it will continue now. The integration will start all over again only after an
integral reset (see chapter 6.8).
Start/Stop Starts or stops a measurement in the Counter/Timer mode.
The Ratemeter or the Search function run continuously, sepa-
rate start of the measurement is not necessary.
Menu Return to the System Menu.
Info Press this button briefly and repeatedly to view information on
the running measurement. Additional information is displayed
depending on the measurement mode, see chapter 6.5.
6.2 Description of the Individual System Menu Items
The following four displays list all system menu items that are
available in an alpha beta contamination probe. We will now
describe these menus and sub-menus in detail.
LB 134 6. Software Functions
55
Figure 6.2: System menu for alpha-beta probe
6.3 Use Internal DR Detector
If the checkbox to the right in this menu row is ticked, this
means that the internal dose rate probe is used, even when the
external probe is connected. When the cursor (left arrow) is al-
ready in this row, the internal probe can be enabled or disabled
by pressing Enter. If it is not enabled, then the external probe is
used (the X has been cleared). When not enabled, the power
supply of the internal probe is turned off to save power. If the in-
ternal probe is disabled and no probe is connected, you will see
the following display. “na” means that the internal probe is not
turned on (not activated).
Figure 6.3: Display with internal probe turned off and
no external probe connected
6.4 Background
The background menu depends on the type of probe that is
connected. Basically, you can always enter the background;
however, with some probes one cannot determine the back-
ground using the measurement function to be started here. For
an alpha beta contamination probe there are two backgrounds
that here are either determined through a background meas-
urement and stored or, if they are already known, can be en-
tered directly.
Dr na
LB 134 6. Software Functions
56
The functions and settings are explained below:
Figure 6.4: Background menu with options for the contamination probe
The currently stored background is always subtracted from
each measurement (in each measurement mode).
Start measurement Starts the background measurement in one or both measuring
channels simultaneously – using the parameters defined on this
page.
The background can also be entered manually in cps in the row
BG α or BG β, provided the Background menu is enabled for
reading and editing. The following display appears after the
start of the background measurement:
Background measurement
a) Ongoing measurement (after 32 seconds)
b) Measurement stopped after 1:03 minutes
Figure 6.5: Background measurement
LB 134 6. Software Functions
57
a) The info line can be used while a measurement is running
to view the accuracy or the time and date.
b) At the end of the measurement, the backgrounds ( and )
can be saved (Save button) and information on the measurement can be viewed (Info button).
During a background measurement, the softkeys have the fol-
lowing functions:
Save This softkey is displayed only when the measurement has been
completed. Press this button to store the measured background
in the Background menu in the line BG α and BG β.
Start/Stop Stop is displayed while a measurement is running, Start is dis-
played if a measurement has been stopped or completed.
Esc Return to the Background menu.
Info Press this button repeatedly and briefly to view the following
additional information:
Accuracy
Elapsed Measuring Time and Preset Time
Date and Time
Negative values For statistical reasons it may happen that the stored and sub-
tracted background is greater than the currently measured
count rate. Mathematically this results in negative count rates.
Negative numbers are suppressed in order not to confuse the
user (display zero).
If the negative values are in fact only a result of statistical fluc-
tuations, then the result will constantly vary around 0. That's a
good sign indicating that the stored and the currently measured
background coincide on the average.
However, if the value 0.000 is visible all the time, this indicates
that the stored background is too high. In this case: Check the
background and, where necessary, carry out a new measure-
ment and store the new value!
LB 134 6. Software Functions
58
Measuring time [s] Enter the measuring time in seconds. It should be at least 60
seconds to obtain accurate measurement results. Note that the
preset measuring time limits the background measurement, no
matter what accuracy is reached!
The actual measuring time can be viewed by pressing the Info
button. It is stored internally and is taken into account in further
calculations.
The background should be measured daily or occasionally
or it should be measured new and stored whenever chang-
ing the environment to avoid false values in the net result!
The stored background is displayed in the Background
menu. This value is subtracted from each subsequent
sample measurement.
Autostart Here the autostart function can be enabled (X) or disabled ( ).
When the autostart function is enabled, a background meas-
urement is carried out automatically using the preset parame-
ters whenever the device is turned on. Upon completion of the
background measurement (by manual stop or expiration of the
measuring time), store the measured background by pressing
the Save softkey. Only then you can start regular measure-
ments (contamination, activity, dose rate) by exiting the Back-
ground menu and the System menu.
Please note: If the autostart function is active, a measurement
should be started only after saving and accepting the result of
the current background measurement.
BG / BG β The currently stored background is displayed. It can come from
a background measurement (see above) or it can be entered
manually. For other contamination probes you see here only
BG [cps].
Manual change:
After selecting this option, press the Enter key.
Move the cursor with the button to the desired position
and set the desired number by repeatedly pressing the ↓↑key.
If this is a multi-digit number, press the button to go to
the next digit and set this digit as described above.
Once the desired value has been entered, press the Enter
key. Thus, the entered digit is stored as a new background.
BG measuring time At the end of a background measurement, the measuring time
is displayed in seconds. If you want to enter the backgrounds
as values, you have to enter the associated measuring time
here; otherwise the statistical error of the subsequent meas-
urement results is calculated incorrectly.
LB 134 6. Software Functions
59
6.5 Measurement Mode
In this menu, you can select three different averaging methods
for the measurement results: Counter/Timer, Ratemeter and
Search Mode. The associated parameters are set in the
Measurement Parameters menu. The selected averaging
mode is retained even after the device has been powered off
and on again. See chapter 1.6 for an explanation of the averag-
ing method.
Proceed as follows On the System Menu the currently set measurement mode is
displayed next to the option Measurement mode.
To change the setting, select the Measurement mode op-
tion (), and press the Enter key. Then, the current setting
is marked by an .
Press the ↓↑ key button repeatedly to scroll through the se-
lectable measurement modes in cyclic order.
Once the desired measurement mode is displayed, press
the Enter key. The selected setting is accepted.
Figure 6.6: Selecting the desired measurement mode
6.6 Measurement Parameters
6.6.1 Ratemeter
If you select the Ratemeter measurement mode, you will see
the following options:
LB 134 6. Software Functions
60
Figure 6.7: Parameters for Ratemeter measurements
Avg. Mode Set the type of averaging. You can select Time Constant or
Accuracy.
Time Const. Enter the desired time constant, i.e. the time to be used to
smooth the measured values. With smaller time constants, the
measurement is more sensitive and reacts more rapidly, but is
less accurate. Default setting is 120 seconds.
Accuracy [%] If the accuracy is defaulted, a time constant is determined from
this accuracy and the actual count rate corresponding to that
accuracy.
Sigma Factor Specifies the number of standard deviations which defines at
which deviation of the currently measured value from the mean
value the time constant will be reset to 1 second and then is in-
creased by one each second until the above time constant is
reached. (good for fast response of displayed value in case of
fast changes of activity)
Cycle Time (s) In Ratemeter mode, the cycle time defines how often storage is
performed or how many times the data are to be transferred via
USB interface. The ratemeter continues to run uninterrupted. If
you press the RESET button, the ratemeter is initialized.
Cycles The cycle parameters for all measurement modes are defined
in this menu:
One defines whether
the measurement is saved only once (setting: 1)
the measurement is stored after each cycle (setting 0, =
endless)
a predefined number of cycles is to be stored (setting N,
where N can be between 2 and 9999).
Auto Save Enable (X) or disable ( ) the automatic save function. Stored da-
ta can be viewed on the Memory menu either on the display or
copied to a memory stick and transferred to a PC. The current
saving process is displayed in the upper left corner of the dis-
play.
Auto Send Enable (X) or disable ( ) the automatic transfer function via USB
to the PC. When enabled, the results are automatically trans-
mitted every cycle time.
LB 134 6. Software Functions
61
6.6.2 Counter/Timer
If you select the measurement mode Counter/Timer, you will
see the following options:
Display for alpha beta contamination probe.
Display for dose rate probe.
Figure 6.8: Parameters for a Counter/Timer measurement,
for two different probes
Measuring Time Measuring time of a cycle in seconds.
Cycles The cycle parameters for all measurement modes are defined
in this menu:
One defines whether
the measurement is to be performed once (setting: 1)
the measurement is to be repeatedly constantly (setting 0)
a predefined number of cycles is to be performed (setting
N, where N can be between 2 and 9999).
Preset Acc. (%) Once the accuracy of the measurement is less than the preset
accuracy, a measurement cycle is stopped even if the preset
measuring time has not yet been reached. If there are two
measuring channels (e.g. alpha and beta channel), the meas-
urement cycle is stopped as soon as both accuracies are below
the two preset accuracies. If you want to stop a measurement
via the preset measuring time, you have to enter a very small
value for the preset accuracy to make sure it will never be
reached, for example, 0.01%.
Auto Save Enable (X) or disable ( ) the automatic save function. Stored da-
ta can be viewed on the Memory menu either on the display or
LB 134 6. Software Functions
62
copied to a memory stick and transferred to a PC. The current
saving process is displayed in the upper left corner of the dis-
play.
Auto Send Enable (X) or disable ( ) the automatic transfer function via USB
to the PC. When enabled, the results are automatically trans-
mitted every cycle time.
6.6.3 Search
If you select the measurement mode Search, you will see the
following options:
Figure 6.9: Parameters for Search mode
Cycle Time (s) Same function as in Ratemeter
Cycles Same function as in Ratemeter
Auto Save Same function as in Ratemeter
Auto send Same function as in Ratemeter
6.7 Nuclides/Measurement Types
Display of the Nuclides/Measurement Types Table with edit-
ing option.
After selecting this menu option, the first 4 nu-
clides/measurement types of the nuclide/measurement type ta-
ble are displayed. The cursor is at the top position. Briefly press
the ↓↑ key to move the cursor down; to move the cursor up, you
have to press this key longer.
Briefly press the Pg up/Pg down key to scroll one page forward
in the nuclide table; to scroll back one page, you have to press
this key longer. In this way, you can scroll through the entire
nuclide table.
Press the key to view new function keys: New, Edit and
Delete, to define new nuclides, edit or delete existing nuclides.
In an alpha beta probe, however, the first six entries cannot be
deleted, in a doserate probe, the first two entries cannot be de-
LB 134 6. Software Functions
63
leted. The following three displays show the first 12 nuclides for
an alpha beta contamination probe.
Figure 6.10: The first twelve nuclide entries for
alpha-beta probe
The next two displays show examples of measurement types
for a dose rate probe.
Figure 6.11: The first eight nuclide entries for a
doserate probe
Contents of the nuclide/measurement type table
The nuclide/measurement type table currently contains about
70 nuclides and 12 measurement types with calibration factors.
Moreover, it includes a nuclide mix for alpha and beta sources
LB 134 6. Software Functions
64
"α-tot" and " -tot". In addition, it includes the units Net [cps]
and Gross [cps] for alpha and beta-gamma SOURCES.
The following information is included for each nuclide: name,
active, radiation type, mass number, unit, two calibration factors
A-100 (according to DIN 25415) and ISO (according to DIN ISO
7503-1), one alarm threshold for the measured value, one
alarm threshold for the integral value, the unit for the integral
value and the time base for the integral calculation that can be
edited by the user.
Figure 6.12: Nuclide parameters for contamination probe
LB 134 6. Software Functions
65
Figure 6.13: Measurement type parameters for a
dose rate probe
The following information is included for each measurement
type: name, active, radiation type, the order in the list, unit, one
calibration factor, one alarm threshold for the measured value,
one alarm threshold for the integral value, the unit for the inte-
gral value and the time base for the integral calculation that can
be edited by the user.
Selection for small nuclide/
measurement type table In the nuclide/measurement type table you can select individual
nuclides / measurement types for the small nuclide / measure-
ment type table (Measurement menu). To select a nu-
clide/measurement type, mark the menu item Active with an X
by pressing the ENTER key. The selected nuclide / measure-
ment type can then be set directly in a measurement. Press the
Enter key again to clear the selection.
Editing the nuclide table Be careful when editing the nuclide table. The calibration fac-
tors have been determined correctly in the factory for all entries.
The setting of the nuclide-specific alarm thresholds is important
for the user to trigger audible and visual alarm signals when
these thresholds are exceeded.
Proceed as follows
Move the cursor () to the desired nuclide.
Press the button to go to the Edit menu. Now press the
Edit button.
This will take you to the page on which the parameters for
that nuclide/measurement type can be edited.
Enter the desired values.
Confirm your entry by briefly pressing the Enter key.
Figure 6.14: Editing the nuclide parameters of C-11
LB 134 6. Software Functions
66
The parameters in detail:
Name Nuclide name.
Active Change the status to passive or active.
Radiation type Shows the type of radiation of the nuclide ( or orγ or n).
Mass number Physical mass number of the nuclide or order of the measure-
ment type (1, 2, 3, ……)
Unit Unit of measurement, e.g. cps, Bq/cm², µSv/h, mrem/h etc.
Calibration factor (A-100) Calibration factor according to DIN 25415 standard relative to
an area of 100 cm². For gross or net, the calibration factor is
always "1". The second calibration factor appears only for con-
tamination probes; for all other probes there is only one calibra-
tion factor.
Calibration factor (ISO) Calibration factor according to DIN ISO 7503-1 standard. For
gross or net, the calibration factor is always "1". The second
calibration factor appears only for contamination probes; for all
other probes there is only one calibration factor.
Alarm threshold An alarm threshold can be set for the individual nu-
clides/measurement types.
If the stored alarm threshold is exceeded during a measure-
ment, the measured values and the top LED start flashing and
you will hear a permanent alarm, which will be turned off only
when you quit the measurement mode or when the measured
value has dropped below the alarm threshold. Moreover, the
exceeding of the alarm threshold is also indicated on the bar
graph: The percent indication is switched over using the factors
10, 100 and 1000, so that it is immediately apparent by which
factor the entered threshold has been exceeded.
Limit values Under the Radiation Protection Ordinance of August 1, 2001 in
Germany the limit values for contaminations are nuclide-
specific. In operational monitoring areas, these limit values are
10x higher than outside the monitored area. May be different in
other countries.
Examples for limit values outside monitored areas in Bq/cm²:
C-14: 100
S-35: 100
Ca-45: 100
Fe-55: 100
Ni-63: 100
Tc-99: 10
Tl-201: 10
LB 134 6. Software Functions
67
Sr-90: 1
When the limit value is exceeded, measures have to be tak-
en immediately to avoid the spreading of the contamination
(German Radiation Protection Ordinance § 44).
Moreover, the measured value has to be recorded in this
case.
Integral threshold Measured values are integrated each second during the meas-
urement. For example, the summation of the dose rate (µSv/h)
results in the dose µSv. For contamination probes we can inte-
grate the net values (cps), and then we would get counts. The
value obtained is compared with the integral threshold and an
alarm message is generated when this threshold is exceeded.
Integral unit Here the unit of the integral value is entered as text, e.g. µSv,
mrem, counts or pulses.
Time base During the measurement, the current integral value or the dose
and the integration time elapsed until then is determined every
second through addition. If you have selected the unit counts
per second (cps), you get counts through adding up (counts). If
you have selected the unit µSv/h, as for the dose rate, then the
time base is not seconds but hours. Therefore, before the addi-
tion, the value must be divided by 3600, since every second is
added up. This divisor is selected correctly when entering the
integral calculation time or the time base. You can select s, m
or h.
6.8 Integral Reset
The integral values / dose and the associated integral time are
reset.
Figure 6.15: Resetting the integral values and integral time
LB 134 6. Software Functions
68
6.9 Display Mode
You can select one of three possible display modes for a con-
nected alpha beta contamination probe.
Figure 6.16: Selection options in the display mode
In the first case, the alpha and beta channel are shown the
same size.
Figure 6.17: Display mode α + β
In the second case, the alpha channel result is displayed large
and the result of the beta channel will appear in the info line.
Figure 6.18: Display mode α
In the third case, the beta channel result is displayed large and
the result of the alpha channel will appear in the info line.
Figure 6.19: Display mode β
LB 134 6. Software Functions
69
6.10 Upload and Download Memory and Parameters
The following storage operations and parameters up- and
downloads can be performed with this menu item:
The results entered in the memory can be displayed
sequentially on the display.
The entire memory can be erased with a single com-
mand.
The entire memory content can be transferred to a USB
stick and can be evaluated on a PC. Therefore the
Berthold PC program for the LB 134 is necessary.
All parameters can be written to the USB stick with a
single command.
All parameters that were previously written to the USB
stick can be transferred to another LB 134. With the
Berthold PC program LB 134, the parameters can be
written to the USB stick from a file and then transferred
to a LB 134 with the stick. On the other hand, the parameters on the USB stick can be read and archived by
this PC program.
The data memory can be operated in two different
modes. On the one hand, as a finite memory with a current length of 2400 entries. On the other hand, as a
FIFO memory; once the memory is full, the oldest entry
is overwritten by the new data. For this mode, there is a
write pointer and a read pointer for reading the FIFO.
The F²C protocol is used for communication. Both interfaces, USB and RS485, have access to the FIFO with
this protocol. In general, this type of communication
with the FIFO is performed via the RS485 digital data
network. Therefore, there is only one common read
pointer.
The storage of the measured values takes place either via the
corresponding softkey or through the automatic storage function
(see Autosave menu)
When you save the measurement, the number under which the
measured values are stored in memory is displayed on the top
left.
LB 134 6. Software Functions
70
The measurements are stored in the order they have been
saved in the RAM memory. The pages are numbered consecu-
tively; one page is used for each measured value.
Figure 6.20: Options on the Memory menu
Show Memory Shows the current memory contents on the display.
Memory contents of alpha, beta contamination probe in
Ratemeter mode.
Memory contents of alpha, beta contamination probe in Coun-
ter/Timer mode
Memory contents of dose rate probe in Ratemeter mode
LB 134 6. Software Functions
71
Memory contents of dose rate probe in Counter/Timer mode
Figure 6.21: Examples for Show Memory menu
To go to the desired results, you have the following options:
↓↑ key: short push: Next measurement
↓↑ key: long push: Back one measurement
Pg ↓ key: short push: Next page
Pg ↓↑ key: long push: Back one page
If you save a cyclical measurement, you will see in the first line,
for example, (# 2/3) of the current cycle / preset total cycles.
With two measuring channels, the integration time appears
twice, but is always the same size.
Delete Memory Clears the entire memory contents!
Memory USB Stick Writes the entire memory contents to the USB stick. The display
shows: Write data to USB stick successful.
Para USB Stick Writes all parameters to the USB stick. The display shows:
Write data to USB stick successful.
USB Stick Para Writes all parameters from the USB Stick to the LB134. The
display shows: Write data to Memory successful.
Display of memory contents
Example contamination
Line 1: No./Qty., Cycle N of M, LB-number
Line 2: Date, Time, RM/CT, Meas. time s
Line 3: Radiation type, Nuclide, Measured value1, Unit1, accuracy1 %
Line 4: Radiation type, Integral, I.value1, I.unit1, Integration time h
Line 5: Radiation type, Nuclide, Measured value2, Unit1, accuracy 2 %
Line 6: Radiation type, Integral, I.value2, I.unit2, Integration time h
Example dose rate
Line 1: No./Qty., Cycle N of M, LB-number
Line 2: Date, Time, RM/CT, Meas. time s
Line 3: Radiation type, Meas. type, Measured value, Unit, accuracy %
Line 4: Radiation type, Integral, I.value, I.unit, Integration time h
LB 134 6. Software Functions
72
6.11 Parameters
The following device parameters are set on this menu:
Figure 6.29: Menu items under Parameters
6.11.1 Date/Time
Here you can check and set the date and time. This time infor-
mation is used when storing the measured values.
If the memory with the time information is deleted (e.g. by stor-
ing the LB 134 without batteries), the date and time will be au-
tomatically queried when the device is turned on. The entry is
made as shown below: DD.MM.YYYY or HH:MM:SS.
Figure 6.30: Entering the date and time
LB 134 6. Software Functions
73
6.11.2 Language
This menu item allows you to choose German or English as
user interface language.
6.11.3 Device Address
Enter a device address between 1 and 255 for networking with
the RS485 bus. If the LB 134 receives a command via the USB
or RS485 interface, the address contained therein must match
the above address for the command to be processed.
6.11.4 Calibration Type
You can select calibration sets in accordance with DIN ISO
7503-1 and DIN 25415 (A-100). Both types of calibration are
described in detail in chapter 9.5.
6.11.5 Light Off [min]
Here you can enter the automatic switch-off time for the display
backlight. If the backlight is turned on, it will be switched off au-
tomatically when the time preset here is over.
6.11.6 Backlight
Here you can enter the brightness for the display backlight. You
can choose Bright, Medium and Dark. If no key is pressed for
60 seconds, the display light goes out automatically.
6.11.7 Headphones/Relay
Here you can choose whether to connect a relay to the left 6 pin
Fischer jack or a headset to the jack plug socket (3.5 mm diam-
eter). Default is the headset.
An external low-voltage relay can be connected, which is ena-
bled when an alarm limit in the first or second channel is ex-
ceeded. In the event of an alarm, this could be used, for exam-
ple, to operate an external signal lamp. The relay can be sup-
plied with 5V on pin 2 of the Fischer jack, the other terminal of
the relay passes through pin 1 to a transistor, which is internally
protected by a diode (US1K). The maximum current must not
exceed 50 mA. The relay can also be supplied with an external
LB 134 6. Software Functions
74
voltage of +12V; in this case, the ground of the external supply
must be connected to pin 3 (ground). The second connection
goes again to pin 1. Again, the maximum current must be less
than 50 mA.
6.11.8 Power Supply
Depending on the type of battery, the following parameters can
be set:
When Battery has been set, the following display appears:
Figure 6.31: Display when working with batteries
When Accu has been set, the following display appears:
Figure 6.32: Display when working with rechargeable batteries
Battery Type: Battery or Accu
Here you can specify whether the LB 134 should work in the
battery or rechargeable battery mode. If Accu is set, the pa-
rameters Charge Mode and Charge Time are displayed as
well.
Note:
The rechargeable batteries in the device can be charged auto-
matically with the setting Accu when
the device is placed in the wall bracket connected to the
power supply (the device turns on automatically), or
LB 134 6. Software Functions
75
the power supply is connected directly to the device and the
LB 134 is turned on.
To this end, the Charge Mode must be set to On (X). The menu
item Charge Time allows you to limit the duration of the charg-
ing process to 12 hours max. to prevent overcharging. Taking
the device out of the wall bracket and replacing it later, or
switching the device off and then on again results in a restart of
the charging process, provided the charge mode is active. No
charge process is started if the charge is at 80% or higher.
Caution!
The charge function is active only when the device is
turned on!
Charge Mode Here you can set the charge mode (X). Only with setting Accu.
Charge Time Enter the duration of the charge process. Only with setting Ac-
cu. Maximum 12 hours.
Line Voltage The current line voltage in volts is displayed. This value is de-
termined and output by the device.
Battery Voltage Here the current battery voltage in volts (or rechargeable bat-
tery voltage) is displayed. Please take into account that the bat-
tery voltage indication is not correct as long as line voltage is
being supplied, as the battery is not in use during this time.
6.11.9 Hardware
The Hardware menu includes the following parameters:
LB 134 6. Software Functions
76
Figure 6.33: Hardware parameters
In a single-channel probe, e.g. a dose rate probe, the parame-
ters for the second channel do not appear and the table is
slightly shorter. The parameters in detail:
Detector Type:
The LB number of the detector used is displayed here; it may
also be the internal dose rate probe (LB 1346). This parameter
cannot be edited.
Ser. No. Detector:
The serial number of the detector is entered at the factory or
taken from the probe.
Ser. No. Device:
The serial number of the LB 134 device is entered at the facto-
ry; it cannot be edited.
Control Voltage (V):
For many probes, the control voltage is not needed for the
probe high voltage, with a few exceptions. Normally, the value
is set to 2.5V.
LB 134 6. Software Functions
77
Baud Rate:
The baud rate for the USB interface is always 38400 baud and
cannot be changed. The baud rate for the RS485 interface can
be set between 2400 and 38400 and depends on the length of
the data cable and the number of connected devices. The
shorter the line and the less devices are connected, the higher
may be the baud rate. The other parameters are 8 data bits, 1
start bit, 1 stop bit and no parity.
Key Sounds:
When this function is enabled, you hear a short beep whenever
a key is pressed.
Serial ready:
This parameter must always be enabled for data communica-
tion. If this parameter is disabled, then the processor goes to
sleep every second for about 700 ms and the battery life of the
battery/rechargeable batteries is significantly prolonged.
Vinculum Prog On:
To program the USB Vinculum chip in the final testing in the
factory, this parameter must be enabled and then disabled
again for the normal measurement operation.
Dead Time:
The dead time of the detectors for the individual channels in mi-
croseconds are set at the factory.
Fail Time / Fail Threshold:
Each detector has its own fail threshold and fail time because
the backgrounds are very different and we do not want to get
any false alarms, but on the other hand, we would like to get
failure messages as quickly as possible. For contamination
probes, failure monitoring always refers to the beta channel.
During a normal measurement, a counter/timer measurement
monitoring whether the probe count rate has fallen below the
fail threshold is constantly running in the background. This test
LB 134 6. Software Functions
78
is carried out at the end of fail time and, where appropriate, the
error message "Failure" is output. Then this measurement will
start new. See section: 1.7 for information on how to calculate
the values.
Detector Mode: (Only for alpha beta contamination probes)
Three modes can be used for a detector with simultaneous al-
pha/ beta measurement:
Alpha/Beta simultaneously
Only alpha device
Only beta device
If you select alpha only or beta only, the device behaves as if it
were measuring only alphas or only betas. The results of the
other type of radiation don’t appear. With simultaneous al-
pha/beta measurement one can choose three display variants:
Alpha and beta values displayed large, alpha values large and
beta values on the info bar, beta values large and alpha values
on the info bar.
Transmissions for alpha and beta channel
Display or entry of a factor that takes into account the attenua-
tion through the grid. The entry is made separately for and .
Parameter has no influence to cps values.
Upper measuring range
Here, the upper limit value is specified for the allowable meas-
uring ranges of the probes. When exceeding the upper limit,
OVF is displayed instead of the measurement result. In this
case, the integral is stopped.
6.11.10 Factory setting
All parameters can be reset to factory settings. This function
clears all user-defined settings.
6.12 Alarm Type
Here you can set whether the alarm is to be triggered upon ex-
ceeding of the threshold or if the alarm is to be indicated visual-
ly only through the upper red LED. Optical and acoustic alarm
can also be set at the same time.
LB 134 6. Software Functions
79
Figure 6.34 Alarm settings
If the alarm is set to Acoustic or Optical/Acoustic, you will hear,
in addition to the visual alarm, an acoustic signal when the
threshold is exceeded. The respective threshold is stored spe-
cific to the nuclide or specific to the measurement mode in the
nuclide/measurement type table and can be edited.
6.13 Ticks
Here the measuring channel (radiation type) can be set in which
acoustic ticks are to be heard; for an alpha beta contamination
probe there are two entries. For a dose rate probe, only one
channel can be activated.
Figure 6.35: Selection of measuring channel for
acoustic indication of individual events
LB 134 6. Software Functions
80
6.14 Enable Menus
To simplify handling, the device allows you to hide single or all
menus for the measurement operation. On the other hand, the
menus can be enabled to view only the parameters or to view
and edit the parameters.
Figure 6.36: Menus to enable functions
Figure 6.37: Selection rights for the menus
The device supervisor should carefully consider which menu
mode is suitable for his area of work and which menu items
should be accessible to other members of staff. A password is
required to enable the menu. Upon delivery, the password is 0.
At this point, the password can be changed and is still valid af-
ter switching off the device.
LB 134 7. Probes for the LB 134
81
7. Probes for the LB 134
7.1 Internal Dose rate Probe
The integrated gamma dose rate probe is a Geiger-Müller coun-
ter tube and is suitable for the low dose rate range from 0.1
µSv/h to 20 mSv/h and for an energy range from 50 to 1300
keV. Calibration factor: 0.627 µSv/h/cps, intrinsic background:
0.07 cps. The probe is calibrated to the H*(10) standard (ambi-
ent equivalent dose rate). To extend the life of the batter-
ies/rechargeable batteries, the power supply of the internal
probe is switched off in the menu when the probe is not in use.
7.2 Scintillator Probes with ZnS for Contamination Measurements
In this chapter we will describe the Berthold scintillation probes
designed for the measurement of alpha, beta and gamma con-
tamination in detail.
The principle of operation of scintillation counters
In conventional scintillation counters, the radiation to be meas-
ured hits one or several scintillator layers. The resulting light
flashes are passed on directly, or bundled by a suitable reflec-
tor, to the photomultiplier.
The current state of the art
Up to now, sandwich detectors consisting of two layers were
used to measure alpha, beta and gamma radiation: ZnS for the
alpha radiation and plastic scintillators for beta and gamma ra-
diation, with the ZnS layer facing the sample.
The disadvantages of this method are the low sensitivity for
low-energy beta radiation, which must penetrate the ZnS layer,
and a poor discrimination between types of radiation (strong
spillover effects in the beta channel), and high manufacturing
costs. Moreover, with smaller beta energies, such as C-14,
these detectors show a higher position dependence through the
detector surface.
New measurement method by BERTHOLD TECHNOLOGIES
Contamination detectors with ZnS scintillators use a single scin-
tillator made of zinc sulfide (ZnS) to measure the radioactivity.
The radiation to be measured strikes the scintillator. The result-
ing flashes of light are conducted by a suitable reflector to a
photomultiplier with a suitable preamplifier and discriminator
stage and measured.
LB 134 7. Probes for the LB 134
82
Using special evaluation and correlation circuits, the individual
types of radiation such as alpha and beta/gamma/X-ray radia-
tion are distinguished, separated and measured simultaneously
(patented by BERTHOLD TECHNOLOGIES). Part of the spillover of
alpha particles into the beta channel is corrected by software.
The advantages of this method are therefore:
high measuring accuracy
precise distinction of radiation types
high sensitivity even at low energies
low costs for the scintillator, and
ease of maintenance.
Results can be displayed either as a count rate (cps = counts
per second) or as area activities (Bq/cm²).
A metal grid protects the entrance window of the detector
against damage.
Currently, two scintillator probes are available: LB 1342 with
170 cm² surface and LB 1343 with 345 cm² surface. The pa-
tented correlation method allows to measure alpha and beta ra-
diation separately and simultaneously, without any additional
plastic scintillator, and with good efficiency and low local varia-
tion. The temperature dependence in the range -20°C to 40°C
is only about + - 10%. The dynamic range of the beta radiation
is 0 - 50,000 cps and for alpha radiation 0 - 5,000 cps.
Figure 7.1: LB 1342, scintillation probe with 170 cm²
(LB 1341, Xe gas probe in the same enclosure)
LB 134 7. Probes for the LB 134
83
Figure 7.2: LB 1343, scintillation probe with 345 cm²
The scintillator is applied on a transparent carrier. The foil is
stretched over a frame and protected by a metal grid. The de-
tector is fixed to the underside of the cover with four screws.
The frame with foil can easily be exchanged. The radiation en-
trance window can be protected by a metal protection plate.
The reflector and the photomultiplier are located in the case, di-
rectly behind the scintillator. The enclosure also accommodates
the electronics with evaluation and correlation circuit. The asso-
ciated high-voltage is already set at the factory. A service
adapter is required to check and change the high voltage; this
work must be carried out by experienced service personnel.
7.2.1 Cleaning the Detector Window of
Contamination Probes with Scintillator
The window foil of the detector is sensitive to mechanical dam-
age. It is therefore protected by a protective grid. However, eve-
rything should be done to avoid destruction of the window foil
(sharp objects, measurement on stubble fields, rose bushes
and cat's paws!).
For easy cleaning of a dirty window foil, you can take off the
outer protective grid after cautiously loosening the Phillips
screws.
Carefully clean the detector window foil with a soft brush (dust)
or with alcohol or detergent solution. Then dry it using a hair-
dryer that must not be too hot. When you re-insert the protec-
tive grid, please be careful not to damage the foil with the
screws or the screwdriver!
LB 134 7. Probes for the LB 134
84
7.2.2 Changing the Window Foil of Contamination
Probes with Scintillator
A damaged detector window foil can easily be replaced by the
user. BERTHOLD TECHNOLOGIES supplies a foil stretched over a
frame as spare part.
When replacing the foil, make sure that
the exchange takes place in a dry and dust-free place,
moisture or dirt cannot penetrate into the gap during the ex-
change!
the frame is replaced in semi-darkness, as the photomultipli-
er and the scintillator are sensitive to light. Do not work with
the device for 12 hours to allow the phosphorescence to decay.
Proceed as follows
Change the foil in a darkened room (semi-darkness), as
the photomultiplier and the scintillator will be exposed
to light in the course of this process.
Turn device off and, if necessary, pull the power cord.
Place the device with the detector facing up onto a solid,
clean support.
Open the 4 Phillips screws holding the protective grid.
Take off the protective grid.
Remove the frame with foil.
Insert the new frame with the foil such that the sealing lip sits
perfectly to rule out any incidence of light.
Attach protective grid again and fix it with the 4 Phillips
screws.
Wait 12 hours before you start working with the device
to allow the phosphorescence radiation to decay.
LB 134 7. Probes for the LB 134
85
Technical data:
Sensitive
detector area
LB 1342:118mm x 145mm, 170 cm²
LB 1343: 150 mm x 230 mm, 300 cm²
Entrance
window
Layer thickness: 6um
Weight per unit area: 0.4 mg/cm²
Geometric
transmission
80%
Background
LB 1342: Alpha channel: approx. 0.1cps,
beta channel: approx. 10cps
LB 1343: Alpha channel: approx. 0.1cps,
beta channel: approx. 15cps
Sensitivity to 1
µSv/h external
gamma radiation
(Cs 137)
Alpha channel: not detectable
Beta channel: < 100cps
Spillover
Alpha into beta channel (Po-210): < 20%
Beta into alpha channel (Sr-90): < 2*10-5
Measuring range
(linearity deviation error
< 10%)
Alpha channel: 0 – 5 000cps
Beta channel: 0 – 50 000cps (for alpha channel
< 750cps)
Local variation
Responsiveness
Both channels: 20%
Temperature
range
Temperature range operation: -20°C ... +40°C
(no condensation)
Stability of background over T-range: 10%
Temperature range storage: -40°C ... +60°C
Protection type
IP53
Overrange
indication
β: >50000cps Overrange Indication
α: >5000cps Overrange Indication
Light-proof/
Entrance
window
Sunlight <10cps
External
magnetic fields
Close to PC monitor no visible influences
LB 134 7. Probes for the LB 134
86
7.3 Contamination Probes LB 1231 and LB 1233
Two different hand probes as proportional counters are availa-
ble for contamination measurements:
1. LB 1231 with beta-gamma-xenon detector LB 6357
2. LB 1233 with alpha-beta-P10 gas flow counter tubes LB
6359
The LB 1231 probe with its entrance window made of a very
thin titanium foil can only measure beta/gamma radiation, the
LB 1233 with its very thin entrance window made of a Mylar foil
can in addition measure alpha radiation.
Design of the hand probes
Protective case with exchangeable detector:
The proportional counter tube is fixed to the protective case with
handle (hood) by means of snap locks (Figure 7.3).
Figure 7.3: Probe LB1231
The hood incorporates a small printed circuit board (Figure 7.4)
for coding the connected detector.
LB 134 7. Probes for the LB 134
87
Figure 7.4: Basic assembly of the contamination probes,
the probe can be connected to the UMO LB 123
and also to the LB 134.
A foam rubber edge between case and detector protects the
electronics of the hand probe from humidity and water. The 8pin cable connection from the basic unit LB 134 is waterproof.
The protective case accommodates an electronic board (contamination probe adapter) which is connected to the respective
counter tube via a flat ribbon cable and serves to identify the
detectors. The connected probe type is transferred to the software program in the LB 134 and there it activates the respective parameters and calibration factors.
Figure 7.5: Protective case (bottom view)
LB 134 7. Probes for the LB 134
88
Both counter tubes consist of a gas-filled counting chamber with
counting wires. The counter tubes incorporate the necessary
electronics such as amplifier and high voltage generator; therefore, the plug-in connection between the case (hood) and the
detector does not carry any high voltage, so there is no hazard
in touching it.
The respective operating voltage and the high voltage values
for plateau measurements are set to the optimum value for
each counter tube at the factory.
Operating point for 2 contamination probes
Detector LB 1231 LB 1233
(Xenon) (P10 Gas)
Beta HV 1850 V 1800 V
Alpha HV --------- 1100 V
A service adapter is required to check and change the high
voltage; this work must be carried out by experienced service
personnel.
7.3.1 LB 1233 with Alpha-Beta P10 Counter Tube
LB 6359 and Refill Station
This counter tube is designed as follows:
Electronic part as an attachment to the counting chamber, the
counting chamber with counting wires, the replaceable window
foil (metallized plastic on both sides, 0.3 mg/cm2) and the mesh
grid frame.
This detector can be connected to a local or central P10 gas
supply. The detector is automatically refilled and flushed when it
is placed into the wall holder.
Figure 7.6: Wall bracket for LB 1233
LB 134 7. Probes for the LB 134
89
A P10-gas cylinder (local) with double pressure reducer or a
central P10 gas supply can be used to flush and fill the detector. The P10 gas is a gas mixture consisting of 90% argon and
10% methane.
A pre-connected pressure regulator or a needle valve
should be used for the central gas supply. The maximum
flow rate should not exceed 100 cm³/min!
Gas is supplied and drained via 2 self-closing valves each at
the wall bracket and on the rear of the counter tube. Place the
hand-held probe into the wall bracket (see Figure 7.6) such that
the measuring area of the counter tube is facing you. Make sure
that the valves are pushed into each other (at the end you have
to overcome a slight resistance) until they fit together perfectly.
Thus, the valves will catch and open: P10 gas flows into the detector and exits the counter tube again as soon as an adequate
overpressure has built up. The gas exits via a rotameter which
allows you to set the gas flow to an adequate rate (see Figure
7.7). The rotameter indicates a flow from 0 to 300 cm³/min on a
scale from 0 to 30 (multiplication factor 10). Do not use a higher
flow rate than 100 cm³/min to avoid damage to the window foil!
Figure 7.7: Function of the P10 gas refill station
The detector can be flushed or refilled in the idle position; no
extra flush-cycle is required when using it as a stationary instrument.
LB 134 7. Probes for the LB 134
90
All valves close automatically when the detector is lifted off the
bracket; this stops the gas supply and keeps the P10 gas in the
counting chamber.
The operation life after filling or flushing is at least 8 hours with
a loss in efficiency of less than 5 %. See also Figure 7.8 which
shows the efficiency of a counter tube filled with P10 gas over
the course of 3 days.
Efficacy of the P10 flow-through counter tube as a function
of time.
The following diagram shows the efficiency after a counter tube
filling with P10 gas, for alpha and also for beta sources, as a
function of the time. The average loss in efficiency for beta
sources is 0.1% / h. The average loss in efficiency for alpha
sources is 0.05 % / h.
The diagram illustrates that measurements over 8 hours are
easily possible with one counter tube filling with less than 5%
loss in efficiency.
Figure 7.8: Efficiency of a counter tube filled with P10 gas
as a function of time
Commissioning of the alpha-beta detector with P10 gas supply
1. First, unscrew the valve opener (counter-clockwise) from
one of the two valves of the P10 flow-through counter tube.
The valve opener, a screw with a borehole, ensures that no
over- or under-pressure builds up in the detector during
transport which may damage the detector foil. Keep the
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