Dosimetric Response to Gamma-rays and Neutrons of a Tissue-equivalent Microstrip Gas Counter

In recent years a new generation of tracking particle detectors has been developed for particle physics experiments. One such detector, the microstrip gas counter (MSGC) is similar to the multiwire proportional chamber but consists of fine strips of metal on a substrate rather than suspended wires. The main feature of this device is the sub-millimetre readout spacing. When filled with tissue-equivalent (TE) gas at low pressure and constructed of TE materials, such a device may easily be configured to simulate submicron tissue site sizes. In this work, the microdosimetric response of this 'TE-MSGC' to photons and neutron in the range of 100 keV to 14.8 MeV is investigated. It is demonstrated through measurements and Monte Carlo simulations that, despite having a sampling region of unusual shape for a tissue-equivalent proportional counter (TEPC) based dose equivalent meter, the TE-MSGC provides very good estimates of the ICRU-57 quantities of interest, i.e. H*(10) and (Q).