Understanding of the microdosimetric quantities obtained by a TEPC

Abstract

A lineal energy, y and a specific energy, z are fundamental microdosimetric quantities for describing a radiation energy deposition event in a microscopic volume simulating a human tissue cell. They can be measured by using a low pressure Tissue Equivalent Proportional Counter (TEPC) with a so-called Bragg-Gray cavity principle. One of the advantages of using a TEPC is that it can directly evaluate a mean quality factor of the neutron in a mixed radiation field from the measured dose-mean lineal energy by applying a quality factor and LET relationship. From this mean quality factor and the absorbed dose estimated in terms of the frequency-mean specific energy, we can further evaluate a neutron dose equivalent for a radiation protection purpose. In this paper were described the results of the lineal and specific energy measurement in the KAERI 252Cf neutron calibration field by a low pressure TEPC system designed and manufactured by the Health Physics Department at KAERI. Mean quality factors and dose equivalents of 252Cf neutron were then evaluated from the measurement results of the lineal and specific energy values.