Microdosimetric Studies in Mixed Neutron and Gamma Ray Fields Using Triple Gem Tissue Equivalent Proportional Counters

Abstract

Canadian Nuclear Laboratories (CNL) is exploring the possibilities of using a Gas Electron Multiplier (GEM) for a new type of Tissue Equivalent Proportional Counter (TEPC).  In experimental microdosimetry using a TEPC, the effects of ionizing radiation on biological targets are studied by investigating the statistical distribution of energy-deposition events at a microscopic level.  Currently two types of GEM-based TEPC designs are being investigated experimentally at CNL.The first design is a Triple GEM TEPC with a single large readout pad.  Due to the large surface area of the anode, it has a higher sensitivity to neutron radiation compared to that of conventional spherical TEPCs.  The second design is a Triple GEM TEPC with a two dimensional (2D) readout board.  Each charge-collecting pad in the 2D structure represents a single miniature TEPC that can simulate a tissue site size from a fraction of a micron down to tens of nanometers.