LUDLUM MODEL 44-7 Alpha, Beta, Gamma
Detector
July 2012
Serial No. PR090405
and succeeding Serial Numbers
LUDLUM MODEL 44-7 Alpha, Beta, Gamma
Detector
July 2012
Serial No. PR090405
and succeeding Serial Numbers
STATEMENT OF WARRANTY
Ludlum Measurements, Inc. warrants the products covered in this manual to be free of
defects due to workmanship, material, and design for a period of twelve months from the
date of delivery. The calibration of a product is warranted to be within its specified
accuracy limits at the time of shipment. In the event of instrument failure, notify Ludlum
Measurements to determine if repair, recalibration, or replacement is required.
This warranty excludes the replacement of photomultiplier tubes, G-M and proportional
tubes, and scintillation crystals which are broken due to excessive physical abuse or used
for purposes other than intended.
There are no warranties, express or implied, including without limitation any implied
warranty of merchantability or fitness, which extend beyond the description of the face
there of. If the product does not perform as warranted herein, purchaser’s sole remedy
shall be repair or replacement, at the option of Ludlum Measurements. In no event will
Ludlum Measurements be liable for damages, lost revenue, lost wages, or any other
incidental or consequential damages, arising from the purchase, use, or inability to
product
.
use
RETURN OF GOODS TO MANUFACTURER
If equipment needs to be returned to Ludlum Measurements, Inc. for repair or calibration, please send to
the address below. All shipments should include documentation containing return shipping address,
customer name, telephone number, description of service requested, and all other necessary information.
Your cooperation will expedite the return of your equipment.
ATTN: REPAIR DEPARTMENT
501 OAK STREET
SWEETWATER, TX 79556
LUDLUM MEASUREMENTS, INC.
800-622-0828 325-235-5494
FAX 325-235-4672
Table of Contents
General 1
Specifications 1
Prelimin ar y Instructions 2
Operating P rocedures 3
Parts List 4
Assembly Drawing 5
Response Curve 6
Model 44-7 Technical Manual
Page 1 July 2012
GENERAL
The Model 44·7 GM (end window) Detector will detect alpha, beta, and
gamma radiation. Its configuration allows for easy surveys or leak wipe
testing setup. The detector is energy dependent, over-responding by a
factor of 6 in the 60-100 keV range when normalized to l37Cs.
The thin mica window is protected by a 79% open, stainless steel screen
that can be removed. The GM tube can be easily replaced if necessary.
The G M detector operates between 850 and 1000 V. The tube
manufacturer recommends operation at approximately 900 V. The
recommended instrument input sensitivity is approximately 30 mV or
higher to prevent the detector from double pulsing.
The GM tube face can rupture above 2438 m (8000 ft) altitude pressure.
Consequently, detectors carried in unpressurized aircraft above this
altitude would be subject to failure.
SPECIFICATIONS
DETECTOR: end window halogen quenched GM
WINDOW: 1.7±0.3mg/cm
2
WINDOW AREA: active is 6 cm
mica
2
(0.93 in2); open is 5 cm2 (0.78 in2)
EFFICIENCY(4π geometry): 2% for
14
C; 10% for 90Sr/90Y; 7%
for 99Tc; 7% for
239
Pu; 0.1% for
125
SENSITIVITY: typically 2100 cpm/mR/hr
I
ENERGY RESPONSE: energy dependent
BACKGROUND: 40 cpm
DEAD TIME: typically 200 microseconds
COMPATIBLE INSTRUMENTS: general purpose survey meters,
rate meters, and scalers
OPERATING VOLTAGE: 900 V
Model 44-7 Technical Manual
Page 2 July 2012
CONNECTOR: series "C" (others available)
CONSTRUCTION: anodized aluminum housing
TEMPERATURE RANGE: -15 to 50 °C (5 to 122 °F); may be
certified to operate from -40 to 65 °C (-40 to 150 °F)
SIZE: 4.6 x 14.7 cm (1.8 x 5.8 in.) (Dia x L)
WEIGHT: 0.5 kg (1 lb)
PRELIMINARY INSTRUCTIONS
UNPACKING AND REPACKING
Remove calibration certificate or detector functional check certificate
and place it in a secure location. Remove the detector and accessories
(cable, etc.) and ensure that all of the items listed on the packing list are
in the carton. If more than one detector is in the carton, refer to the
calibration certificate(s) for serial number (S/N) match. The Model
44-7 S/N is located on the side of the detector near the connector. To
return the instrument for repair or calibration, provide sufficient
packing material to prevent damage during shipment and appropriate
warning labels to ensure careful handling.
The following items and information should also be included to
ensure a quick turn-around time on your repair calibration:
• instrument(s) and related cable(s)
• brief information as to the reason for return
• description of service requested
• return shipping address
• customer name and telephone number
NOTE: When shipping a Model 44-7 by air, it is necessary
to ship the tube in a sealed container to avoid sudden
atmospheric changes, which could rupture the tube.
Model 44-7 Technical Manual
Page 3 July 2012
OPERATING PROCEDURES
CONNECTING DETECTOR TO INSTRUMENT
Connect one end of the cable provided to the detector by firmly
pushing the connectors together while twisting clockwise a quarter of a
turn until it latches. Repeat the process in the same manner with the
other end of the cable and the instrument.
TESTI N G THE DETECT OR
1. Ensure that the instrument HV is at the proper setting for the
detector.
2. Connect the detector to the instrument and check for a proper
background reading (typically 25 to 50 cpm at a background level of
8 to15 µR/hr.
3. Expose the detector to a check source and verify that the
instrument indicates within 20% of the check source reading
obtained during the last calibration. Alternatively, expose the
detector to a check source of a known value and verify that the
detector gets greater than or equal to the efficiency listed in the
specification section of this manual.
4. Instruments that meet these criteria are ready for use. Failure to
meet these criteria may indicate a malfunction in the detector.
Model 44-7 Technical Manual
Page 4 July 2012
PARTS LIST
Model 44-7 Alpha-Beta-Gamma Detector
Ref. No. Description Part No.
UNIT Completely Assembled 47-1536
Model 44-7 alpha-beta-gamma detector
1 ea. Detector Body 7002-065-01
1 ea. End Cap 7002-065-02
1 ea. GM Tube 01-5006
(LND 723, TGM N210)
2 ea. Sponge 7002-065-04
1ea. Socket 01-5025
1 ea. Connector, UG 706/U 13-7751
1 ea. O-Ring 2-128 16-8284
3 ea. Screws, 4-40 x 3/16 FH 17-8811
1 ea. Red Protective Cap 03-5474
1 ea. Cap Model 44-7 Grid with O-Ring
4002-216
Model 44-7 Technical Manual
Page 5 July 2012
Model 44-7 Technical Manual
Page 6 July 2012
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