Study of a planar cascaded GEM TEPC with sealed chamber for the radiation detection in microdosimetry

Abstract

In the field of radiation detection in microdosimetry, the Tissue Equivalent Proportional Counters (TEPCs) are the key detector options in determining the radiation quality. In this paper, two different structures of TEPCs were introduced, and their electric field uniformity and angular dependence were disscussed. A planar cascaded GEM TEPC with sealed chamber was developed in the laboratory and the general materials used in the detector were tested for outgassing characteristics. The experimental results showed that the polyether ether ketone (PEEK) had the lowest outgassing rate among all tested materials and were selected as the main assembly materials of the TEPC detector. The 241Am was used as the built-in radioactive source for detector calibration, and the detector gain characteristics were studied. The long-term operating stability was tested at working pressure of 54.72 kPa, with a gain consistency of better than 97.8% over 7 days (168 hours) and relative gain variation less than 1% over 4 days (96 hours).