Fluke 943-25 User Manual

Victoreen®

943-25, 943-25A, 943-25B, 943-25T,

943-25TA, 943-25TB, 943-26, 943-26A,

943-26B, 943-26TT, 943-26TA, 943-26TB

Beta Detectors

March 2005
Manual No. 943-25-1 Rev. 2
©2004, 2005 Fluke Corporation, All rights reserved. Printed in U.S.A.
All product names are trademarks of their respective companies

Users Manual

Fluke Biomedical

Radiation Management Services

6045 Cochran Road
Cleveland, Ohio 44139

440.498.2564

120 Andrews Road
Hicksville, New York 11801

516.870.0100

www.flukebiomedical.com/rms

Table of Contents

Section 1: Introduction................................................................................................ 1-1

1.1 General Description ..................................................................................... 1-1

1.2 Application ................................................................................................... 1-1

1.3 Specifications............................................................................................... 1-1

1.4 Functional Description ................................................................................. 1-2

1.5 Receiving Inspection.................................................................................... 1-3

1.6 Storage ........................................................................................................ 1-3

1.6.1 Control of Items in Storage..................................................................... 1-3

1.6.2 In Case of Fire........................................................................................ 1-3

1.6.3 Removal from Storage............................................................................ 1-3

1.7 Procedures, Warnings, and Cautions .......................................................... 1-3

Section 2: Operation.................................................................................................... 2-1

2.1 Installation.................................................................................................... 2-1

2.2 Detector Operation ...................................................................................... 2-1

2.3 Detector Replacement Parts........................................................................ 2-2

Section 3: Theory of Operation................................................................................... 3-1

3.1 Scintillator and Photomultiplier Tube ........................................................... 3-1

3.2 Preamplifier.................................................................................................. 3-1

Section 4: Maintenance, Calibration, and Troubleshooting..................................... 4-1

4.1 Maintenance ................................................................................................ 4-1

4.1.1 Detector Disassembly............................................................................. 4-1

4.1.2 Detector Assembly ................................................................................. 4-1

4.2 Calibration.................................................................................................... 4-2

4.3 Calibration Where Calibration Date is Available .......................................... 4-2

4.4 Calibration Where Detector is a Replacement Part ..................................... 4-3

4.5 Troubleshooting ........................................................................................... 4-3

4.6 Safety Related Detectors ............................................................................. 4-4

4.7 Commercial Detectors ................................................................................. 4-4

4.7.1 Preliminary ............................................................................................. 4-4

4.7.2 Dynode Test Measurement .................................................................... 4-5

4.7.3 Preamplifier Checkout ............................................................................ 4-5

4.8 Replacement Parts ...................................................................................... 4-6

Appendix A: Applicable Drawings..................................................................................A-1

A.1 Applicable Drawings ....................................................................................A-1

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Introduction

General Description

1

Section 1

Introduction

1.1 General Description

The 943 series beta detectors are designed to be sensitive to a beta radiation source.

Although the 943 series beta detectors are functionally identical, the detectors differ in the material used
for the housing; the material used for the end window, and in the response ratio achieved through the
scintillation disc area variations (refer to Section 1.2, Specifications).

Two end window materials are used for the 943 series beta detectors. The mylar end window is used for
replacement of existing beta detectors with similar windows. The beta detectors with titanium end
windows offer greater durability and ease of decontamination.

The beta detector has preamplifier circuitry located in the interior of the overall protective housing. The
preamplifier provides pulse conditioning and cable driving capabilities to match the input characteristics of
the Victoreen instruments used to monitor detector output. The detector is supplied with an eight (8) foot
coaxial cable that normally terminates in a junction box located within a sampling system.

1.2 Application

The detector can be used with Victoreen ratemeters or Scaler Module 960SF. Ratemeters are used with
beta detectors in small single channel analog monitoring systems while scaler modules and detectors are
primarily used in multiple channel digital monitoring systems.

1.3 Specifications

Detector

Dimensions 9 x 2.5 in (22.9 x 6.4 cm)

Weight 3 lbs (1.4 kg), approximately

Housing Stainless Steel 943-25, 943-25A, 943-25B, 943-25T, 943-25TA, 943-

25TB
Carbon Steel 943-26, 943-26A, 943-26B, 943-26T, 943-26TA, 943-

26TB

Power +2000 VDC @ 500 uA, +15 VDC @ 50 mA, -15 VDC @ 50 mA

Connector MS 3106E 2427B

Operating Temperature 32° to 122°F (0° to 50°C)

Storage Temperature 32° to 104°F (0° to 40°C)

Relative Humidity 0 to 95% non-condensing

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Victoreen 943-25, 943-26

Operators Manual

Response Ratio: 1:1 943-25, 943-26, 943-25T, 943-26T
10:1 943-25A, 943-26A, 943-25TA, 943-26TA
100:1 943-25B, 943-26B, 943-25TB, 943-26TB

End Window Material Mylar 943-25, 943-25A, 943-25B, 943-26, 943-26A, 943-26B
Titanium 943-25T, 943-25TA, 943-25TB, 943-26T, 943-26TA, 943-26TB

Preamplifier

Maximum Pressure 30 psi
(Face Exposure)

Rise Time < 60 ns

Input Impedance > 50 kilohms

Output Coupling AC

Voltage Gain 6 V/V

Configuration Voltage sensitive

Output Polarity Negative

Output Impedance 50 ohms

Maximum Cable Length 1500 ft

Maximum Pulse Amplitude @ -6 V
Maximum Cable Length

Dead Time Approximately 10 us @ 8 ft cable length

Maximum Count Rate 10

The beta detectors have been assembled with parts selected for the reliability required in a nuclear
application. Any unauthorized repairs made to the detectors utilized in nuclear applications will void the
safety-related rating. Safety-related detectors must be returned to Fluke Biomedical, Radiation
Management for authorized, qualified (ANSI 45.2.6, Skill Level II) service.

7

1.4 Functional Description

The Victoreen beta scintillation detector is shown in block diagram form in Figure 1-1. The detector
consists of a scintillation disc, a photomultiplier tube, a preamplifier assembly, and various interconnecting
cables connecting the detector, readout, and the detector power supply that is located at the ratemeter or
scaler module.

Figure 1-1. Block Diagram, 943 Series Beta Detector

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