Evaluation of a microdosimeter designed for measurement of neutron lineal energy distribution and determination of its quality factor

Energy response of common neutron dosimeters has a significant deviation. Our goal is to construct an ambient neutron dosimeter as an array of microdosimeters whose response has less dependency on neutron energy. Before construction, the behavior of the microdosimeter as a tissue equivalent in neutron fields has been investigated. The cylindrical sensitive volume of the microdosimeter with 5 mm of diameter and the height filled with a tissue equivalent (TE) gas has been selected to behave like a tissue spherical volume of 1 μm diameter. The walls have been considered as TE plastics with a thickness of 2 mm. The lineal energy distribution for a few single energies of neutrons and also for the energy spectrum of 241Am-Be source has been calculated using Geant4 toolkit and the quality factors have been worked out. The calculated lineal energy distributions and the values of quality factor for dose equivalent measurement are found to be in good agreement with the experimental measurements reported in ICRU-40. The results show that the designed microdosimeter which is equivalent to the tissue with a good approximation, can be used as a part of the ambient dosimeter for measurement of dose-equivelant in neutron fields.