Ionization Quenching Factor Measurement of Helium 4

D. Santos (1) , F. Mayet (1) , O. Guillaudin (1) , T. Lamy (1) , S. Ranchon (1) , A. Trichet (1) , P. Colas (2) , I. Giomataris (2)

1 LPSC - Laboratoire de Physique Subatomique et de Cosmologie
2 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers

The ionization quenching factor (IQF) is defined as the fraction of energy released by a recoil in a medium through ionization compared with its total kinetic energy. At low energies, in the range of a few keV, the ionization produced in a medium falls rapidly and systematic measurements are needed. We report measurements carried out at such low energies as a function of the pressure in He4 at 350, 700, 1000 and 1300 mbar. In order to produce a nucleus moving with a controlled energy in the detection volume, we have developed an Electron Cyclotron Resonance Ion Source (ECRIS) coupled to an ionization chamber by a differential pumping. The quenching factor of He4 has been measured for the first time down to 1 keV recoil energies. An important deviation with respect to the phenomenological calculations has been found allowing an estimation of the scintillation produced in He4 as a function of pressure. The variation of the IQF as a function of the percentage of isobutane, used as quencher, is also presented.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]

D. Santos, F. Mayet, O. Guillaudin, T. Lamy, S. Ranchon, et al.. Ionization Quenching Factor Measurement of Helium 4. 2008. ⟨hal-00327052⟩