Measurements of the Neutron Field Parameters with Monitors based on the Gas-Filled Proportional Counters

Abstract

Neutron monitors with the gas filled proportional counters inside and first data were presented at RuPAC-2018 and RuPAC-2021 conferences. It is planned to use such devices to monitor the stability of irradiation conditions during radiation therapy sessions. We present here the calibration procedure for these monitors at AmBe neutron source, and the new data. These monitors have been used to measure the neutron fluence behind the shielding of the 450 MeV/nucleon carbon beam based experimental facility “Shared use Center – radiobiological stand with the carbon beam of the U-70 accelerator at IHEP”. The measurements were supported by the set of extensive simulations using the CERN FLUKA code. Good agreement between the FLUKA simulations and measurements was shown. Even single monitor with lead insertion calibrated at AmBe neutron source allows to have a good result in the real neutron field. The possibility to estimate the fluence of the high energy neutrons with the energy above 10 MeV using data from the pair of monitors was demonstrated. To improve the quality of the measurements one needs to take into account difference between calibration and measurements conditions.