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

Abstract

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.

Measurements of the ionization efficiency of protons in methane

“…We observe a deviation from SRIM, in particular at low energy, that reaches 33% at 2 keV. Similar deviations with lower ionization energy than predicated by SRIM have already been observed in several gas mixtures [18,19,20,21,22]. We recently measured a deviation from SRIM in the opposite direction (measuring more ionization energy) for neon nuclei in neon gas [14].…”

“…The second main conclusion concerns the significant discrepancy between the measured IQF and SRIM simulations since we measure less ionization energy than simulated, as also noted in previous works [18,19,20,21,22]. SRIM is commonly used to determine the IQF in gases for direct DM searches [49,50], however it has known limitations which impact the physics sensitivity of such experiments.…”

“…While complementary models have been developed on this basis (see [8] for details about several models), they do not describe low-energy ions for which the semiclassical approximation usually fails [16,17]. For energies below 50 keV, deviations from the predictions of the Lindhard theory or simulation toolkits have been measured in multiple media: in gases [14,18,19,20,21,22,23], in noble liquids [16,24], and in crystals [12,25,26].…”

Quenching factor measurements of neon nuclei in neon gas

“…It shows reasonable agreement in silicon and germanium but also in LXe and LAr [41], [44]. Two measurements in gases were performed in 4 He and isobutane, [16] [17]. They showed some discrepancy between Lindhard and their experimental results as well as with the SRIM simulation.…”

“…The COHERENT collaboration, focusing on studying CEνNS [14], has measured the QF for CsI[Na] between 5 and 30 keV. However, few quenching factor measurements have been done on gas mixtures: 4 He and isobutane [16], [17]. To the best of our knowledge, there are no existing quenching factor measurements in pure neon or a mixture of neon and methane, the latest being the primary gas mixture used by the NEWS-G collaboration.…”