Methods for characterizing a radiation detector for specifying radiation fields during testing against standards for homeland security applications

Published

April 15, 2016

Author(s)

Anne L. Sallaska, Leticia Pibida, Ronaldo Minniti, C M. O'Brien

Abstract

A wide variability exists among commercial radiation detection instruments used to measure exposure rate or ambient dose equivalent rate. These instruments are used to measure both the radiation background and radioactive sources strengths to determine the radiation field be used to test other types of radiation detection systems against different consensus standards. Most radiation fields specified in the ANSI standard are quite low, ranging from 5 to 50 µR/h above background. Due to the radiation fields being such low in intensity, the uncertainty of the measurements made with these instruments can be potentially quite large. As a result of these large uncertainties, it is possible that the response of the various parameters being tested by the standards (e.g., alarm indication, radionuclide identification) will be dependent on the specific radiation detector employed by the testing laboratory. In this work, measurements and calculations were performed with a gamma radiation detector model GE RSS-131ER and compared to previously tested instruments, showing a marked decrease in the uncertainty of the measured radiation field. Consistency in testing results across laboratories could improve with a shift in the standards' requirements: For example by specifying for the test the emission rate or activity of the source and a source-to-detector distance instead of specifying the exposure rate or ambient dose equivalent rate of the radiation field.

Citation

Technical Note (NIST TN) - 1916

Report Number

1916

NIST Pub Series

Technical Note (NIST TN)

Pub Type

NIST Pubs

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DOI Link

Keywords

radiation detection for homeland security, ANSI N42 standards, testing of radiation detection equipment

Citation

Sallaska, A. , Pibida, L. , Minniti, R. and O'Brien, C. (2016), Methods for characterizing a radiation detector for specifying radiation fields during testing against standards for homeland security applications, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.TN.1916 (Accessed October 21, 2025)