Ionization Quenching Factor measurement of 1 keV to 25 keV protons in Isobutane gas mixture

Abstract

The French Institute for Radiation protection and Nuclear Safety (IRSN) is providing reference neutron fluence energy distribution at its standard monoenergetic neutron fields, produced at the AMANDE facility. The neutron energy is assessed by measuring the recoil nuclei energy in a μTPC detector, the LNE-IRSN/MIMAC detector. The knowledge of the ionization quenching factor (IQF) is fundamental to determine the kinetic energy of the recoil nuclei. For some various gases and pressures, discrepancies of about 15% were observed between IQF calculations using the SRIM software and experimental measurements. No data are available for the iC4H10 + 50% CHF3 gas mixture which are used for measurements from a few keV up to 565 keV neutron energies in the μTPC detector. The experimental determination of the IQF is of primary importance to provide reference neutron fluence energy distribution. After a short description of the experimental set-up, this paper presents the first results of the IQF measurements in a iC4H10 + 50% CHF3 gas mixture in the energy range 1 keV – 25 keV.