A Proposed Four-element Neutron-photon-beta Thermoluminescence Dosimeter

Abstract

It is common practice for a worker exposed to a mixed field with neutrons to wear both a photon-beta dosimeter and a neutron dosimeter. In this study, a thermoluminescence dosimeter has been designed and is proposed for use in mixed fields. The maximum applicable ranges of the mixed field can have photons with unknown energy from 20 keV to 2 MeV, betas with unknown energy from 147Pm to 90Sr-Y, and neutrons of known energy from thermal to 15 MeV. This proposed dosimeter (a combination of Harshaw beta-gamma thermoluminescence dosimeter and albedo neutron thermoluminescence dosimeter) has an advantage of using a minimum number of thermoluminescence dosimeter elements (therefore, making it less costly) to measure the dose equivalents in a mixed field of neutron, photon, and beta radiation. The basic dosimeter design consists of four thermoluminescence elements of TLD-600 and TLD-700 with different filtrations. Using the high-temperature peak methodology for TLD-600 and a filtration algorithm, the neutron, photon, and beta dose equivalents in a mixed field can be determined. The design, detection principle, and three dosimetric algorithms for three versions of the basic design of the four-element dosimeter are presented and discussed. The work that is required for the proposed dosimeter to be usable when it is made is also presented.

Development and Testing of a Thermoluminescence Dosemeter for Mixed Neutron-Photon-Beta Radiation Fields

“…The standard Harshaw 8814 dosemeter holder was modified to give a configuration as shown in Table 1. This dosemeter design is comparable to the dosemeter design of thick element 4 previously described (1) , except that the thin element in position 3 is 0.15 mm versus 0.09 mm thick.…”

“…The objective of this work was to characterize the response of the prototype dosemeter and develop an algorithm utilizing the high temperature peaks of TLD-600 to quantify the neutron component of the field (1) . The dosemeter performance was tested in various mixed fields and the algorithm was compared to an algorithm that did not utilize the high temperature peaks.…”

“…However, the Cu filter must be used for photon energy determination when any neutrons are present. The following equations are used, as derived in a previous work (1) :…”