Measurement of the response of heat-and-ionization germanium detectors to nuclear recoils

Abstract

The heat quenching factor Q ′ (the ratio of the heat signals produced by nuclear and electron recoils of equal energy) of the heat-and-ionization germanium bolometers used by the EDEL-WEISS collaboration has been measured. It is explained how this factor affects the energy scale and the effective quenching factor observed in calibrations with neutron sources. This effective quenching effect is found to be equal to Q/Q ′ , where Q is the quenching factor of the ionization yield. To measure Q ′ , a precise EDELWEISS measurement of Q/Q ′ is combined with values of Q obtained from a review of all available measurements of this quantity in tagged neutron beam experiments. The systematic uncertainties associated with this method to evaluate Q ′ are discussed in detail. For recoil energies between 20 and 100 keV, the resulting heat quenching factor is Q ′ = 0.91 ± 0.03 ± 0.04, where the two errors are the contributions from the Q and Q/Q ′ measurements, respectively. The present compilation of Q values and evaluation of Q ′ represent one of the most precise determinations of the absolute energy scale for any detector used in direct searches for dark matter.

The scintillation and ionization yield of liquid xenon for nuclear recoils

“…In Ge the agreement between experiment and the Lindhard prediction is very good, above 10 keVr [33]. Below 10 keVr measured values are as much as Â2 above the Lindhard prediction [34].…”

Scintillation yield and time dependence from electronic and nuclear recoils in liquid neon

“…The first of these is the Lindhard effect [32], where some of the energy deposited goes into heat instead of the creation of molecules. The Lindhard effect has been shown to be sufficient to explain quenching in germanium [33], but it is inadequate to explain L eff for the noble gases. A second mechanism is known as bi-excitonic or Hitachi quenching [34], whereby…”

Production Yield of Muon-Induced Neutrons in Lead

“…The responses E h of the phonon channel and E i of the ionisation channel to a nuclear recoil with energy E rec is normalized to the response to an electronic recoil of the same energy. As a result, E h and E i are given in electronvolt electron equivalent (eV ee ) and can be parametrized as [105]:…”