Simulation and First Test of a Microdosimetric Detector Based on a Thick Gas Electron Multiplier

We present design of a new microdosimetry detector based on thick gas electron multiplier (THGEM). A prototype detector was designed for a cylindrical sensitive volume with 5mm diameter and 5mm height. To optimize the avalanche gain, the electron avalanche process was modeled by varying THGEM thickness, hole diameter and high voltage bias for the tissue-equivalent propane gas. For a THGEM with 0.6 mm thickness and 0.3mm hole diameter, the theoretical avalanche gain reached $\sim {200}$ at a 800 V THGEM bias. The prototype detector was fabricated and tested using the McMaster 7Li(p, p) neutron source. The avalanche gain of the prototype detector was comparable with the gain of the standard microdosimetry detector. Additional THGEMs with various thicknesses were fabricated and are under tests.