Thermoluminescent detectors

Given the importance of the photon heating contribution in plutonium burning fast reactor cores, a comprehensive validation work is under way for ECCO/ERANOS. Within this framework, PSI has contributed with both an experimental and an analytical effort. On the experimental side, thermoluminescent detector (TLD) measurements were performed in some of the aforementioned CIRANO configurations. With regard to methods/calculational aspects, an important effort was necessary to produce consistent neutron kerma factors and photon spectra data (from photon production due to radiative neutron capture, fission, and both elastic and inelastic neutron scattering). 

Neutron doses were detennined using the 9-in. sphere PNR-4 rem meter and from the readings of thermoluminescent detectors (TLDs) ( U and Li) placed inside the 9-in. sphere. Thermal neutron doses were measured using the BFj tube of the PNR-4 instrument and with pairs of Li and Li TLDs. We used albedo neutron dosimeters of the Hankins type and applied file 9- to 3-in. sphere ratio technique to evaluate the albedo readings. Gamma-ray dose measurements were made using TLDs... 

A. Halperin, Activated thermoluminescence (TL) dosimeters and related radiation detectors 187... 

The method of assessing is commonly by thermoluminescence, wherein the number of photons released during the annealing process or heating are detected by a photombe. The procedure was developed for pottery where the kilning process annealed the detector mineral and therefore provided information on the time since anneahng. An alternative method is to use ESR. 

Commercial TL analyzers are available, such as the Harshaw Model 2000 thermoluminescence analyzer. It can be used for routine personnel dosimetry monitoring or for research purposes. The apparatus consists of a TL detector, an automatic integrating picoammeter. and a TL computer processing unit. Pla and Podgorsak (102) have recently described a computerized TL system based on this instrument and a PDP-8E minicomputer. 

This chapter discusses in detail all the neutron detection methods mentioned above, as well as the Bragg crystal spectrometer, the time-of-flight method, compensated ion chambers, and self-powered neutron detectors (SPND). Other specialized neutron detectors, such as fission track recorders and thermoluminescent dosimeters, are described in Chap. 16. 

Chapter 17 deals with special detectors and spectrometers that have found applications in many different fields but do not fit in any of the previous chapters. Examples are the self-powered detectors, which may be gamma or neutron detectors, fission track detectors, thermoluminescent dosimeters, photographic emulsions, and others. 

The second edition follows the same guidelines as the first—namely simplicity in writing and use of many examples. The main structural change is the elimination of Chap. 17 (Special Detectors and Spectrometers) and the relocation of the material in appropriate chapters. For example, rate meters and gas-filled detectors are now discussed in Chap. 5. Self-powered detectors are now included in Chap. 14 along with other neutron detectors. Chapter 16 deals with solid-state track recorders and thermoluminescent dosimeters. 

Because there are so many instruments available, only the use of the ion chamber dosimeter, thermoluminescent dosimeter (TLD), and the low-range beta-gamma radiation detector will be taught in this station. 

In principle, different types of passive detectors can be used such as thermoluminescent materials, electret devices, and solid-state nuclear track detectors. 

ACTIVATED THERMOLUMINESCENCE (TL) DOSIMETERS AND RELATED RADIATION DETECTORS... 

A second type of badge detector is a thermoluminescence dosimeter that traps energy from radiation in a thermoluminescent material that releases this energy when it is heated. These detectors have largely replaced film badges because they are very sensitive and have a linear response over a wide range of doses as well as dose rates. 

External exposure can be measured by personnel monitoring using film badges or thermoluminescent dosimeters (TLD) in occupational and environmental monitoring, additionally, dose rate meters based on G-M tubes, proportional counters, scintillation detectors, etc., are introduced. 

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