Title: Neutron Responses of a Novel Multi-element Microdosimetric Detector and Its Potential for Dosimetry

A prototype multi-element gaseous detector based on THick Gas Electron Multipliers (THGEMs) has been designed and constructed. A THGEM generates a strong electric field within micro-holes of a sub-millimeter thick insulator, which makes electron multiplication possible without the traditional anode wire electrodes encountered in proportional counters. The wireless structure has been chosen to overcome the complicated fabrication and assembly process required for building multi-element microdosimetric detectors using the traditional proportional counter technology. The multi-element design was employed to enhance the neutron detection efficiency, particularly for weak radiation fields frequently encountered in radiation protection applications. The prototype detector consists of 21 cylindrical gaseous sensitive volumes, with equal heights and diameters of 17 mm, built in three alternating layers of tissue-equivalent plastic hexagons. The detector was filled with a propane-based tissue equivalent gas and its responses to various neutron fields were investigated using the 7Li(p,n) neutron source at the McMaster Tandetron accelerator laboratory. Microdosimetric measurements were carried out for the proton energy range of 1.9 to 2.3 MeV and proton current of 50 μA. In this paper, the prototype detector structure is described. Preliminary results on the pulse height measurements and microdosimetric response of this novel detector are presented.