Field dependence of electronic recoil signals in a dual-phase liquid xenon time projection chamber

Abstract

A: We present measurements of light and charge signals in a dual-phase time projection chamber at electric fields varying from 10 V/cm up to 500 V/cm and at zero field using 511 keV gamma rays from a 22 Na source. We determine the drift velocity, electron lifetime, diffusion constant, and light and charge yields at 511 keV as a function of the electric field. In addition, we fit the scintillation pulse shape to an effective exponential model, showing a decay time of 43.5 ns at low field that decreases to 25 ns at high fields. K: Noble liquid detectors (scintillation, ionization, double-phase); scintillators, scintillation and light emission processes (solid, gas and liquid scintillators); charge transport, multiplication and electroluminescence in rare gases and liquids; Time Projection Chambers (TPC) A X P : 1807.07121

Scintillation decay-time constants for alpha particles and electrons in liquid xenon

“…[21]. It coincides with the measured rise of τ t towards lower field strengths, which qualitatively matches the already known behavior of the effective triplet state lifetime which has been observed to decrease with increasing electric field [20,22,46]. Both trends are attributed to recombination dynamics, which affect the photon emission time for excimers produced by recombination and become more noticeable towards weaker fields.…”

“…Results for τ s and f s match with the ones at similar ER energies, with the only disagreement being with the significantly lower f s value published by the LUX collaboration [14]. For f s , the observed dependence on the applied field qualitatively agrees with the Hogenbirk et al measurement for ERs induced by 511 keV gamma photons scattering off LXe [22]. Quantitatively, the f s values measured in that publication are systematically smaller than the ones from this work.…”

“…Using the time difference between the scintillation start time as measured by the first PMT and the corresponding single photons observed in the second PMT, called ∆t in the following, the probability density function (PDF) for the photon arrival time can be determined. Compared to Monte Carlo methods which need to take the detector response and various other parameters into account [11,14,21,22], this technique is inherently more robust against systematic uncertainties.…”

“…This effective model, which has been used by previous publications in either this form or a similar one [11,12,14,21,22], consists of two exponential decays with decay constants τ s and τ t which correspond to the singlet and the triplet state of a xenon excimer, respectively. f s denotes the fraction of scintillation photons emitted from singlet state decays compared to the total number of singlet and triplet decay photons.…”

“…It also affects the measured effective singlet and triplet state lifetimes. For example, the singlet and triplet lifetimes for O(< 1 MeV) ER scintillation signals have been measured to lie around 2.5 ns and 25 ns, respectively, if they happen under an electric field of O(100 V/cm) [14,[20][21][22]. In the case of α-particles, only data at zero field is available which gives roughly 4 ns respectively 24 ns [23][24][25].…”