Lowering the low-energy threshold of xenon-based detectors

Abstract

We show that the energy threshold for nuclear recoils in the XENON10 dark matter search data can be lowered to ∼ 1 keV, by using only the ionization signal. In other words, we make no requirement that a valid event contain a primary scintillation signal. We therefore relinquish incident particle type discrimination, which is based on the ratio of ionization to scintillation in liquid xenon. This method compromises the detector's ability to precisely determine the z coordinate of a particle interaction. However, we show for the first time that it is possible to discriminate bulk events from surface events based solely on the ionization signal.

A Global Analysis of Light and Charge Yields in Liquid Xenon

“…Many detectors use applied electric fields to collect ionization electrons. These data are at 100 V/cm (red) [26], 270 V/cm (green) [26], 530 V/cm (blue) [32], 730 V/cm (purple) [27][28][29], 1000 V/cm (dark red) [30], 2000 V/cm (orange) [26], 2030 V/cm (gray) [26], 3400 V/cm (blue band) [31], 3900 V/cm (orange band) [31], and 4000 V/cm (dark green) [30]. Charge yield relative to that as applied electric field approaches 0, Qn = Qy(F )/Qy(F 0 ).…”

“…The model is constrained using three categories of data sets, each consisting of multiple measurements of yields in liquid xenon. The absolute NR charge yield, Q y , is constrained using twelve measurements across different energies at a range of electric fields [22,[26][27][28][29][30][31][32]. The photon yield is constrained with seven additional measurements [30,[33][34][35][36][37][38] of the parameter L ef f , defined as the zero-field scintillation yield for nuclear recoils relative to that of the 122 keV γ-ray from 57 Co.…”

Liquid noble gas detectors for low energy particle physics

“…It is therefore important to study them simultaneously. The charge yield from xenon recoils tracks has been measured directly in dedicated experiments [53,61] and also indirectly assessed from calibration data of real dark matter detectors [66,146,67]. A relatively high charge yield and weak electric field dependence has been found, against expectations, as shown in Figure 13.…”

Modeling pulse characteristics in Xenon with NEST

“…In the case of liquid xenon as the DR, there are two established empirical models for drift speed [15,24], which are both implemented in NEST. However, the default model is chosen to be [24] because it is a better match to recent data [34]. Also, note that NEST implements a linear dependence on temperature, as outlined in [33].…”