A measurement of the scintillation decay time constant of nuclear recoils in liquid xenon with the XMASS-I detector

The XMASS collaboration

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We report an in-situ measurement of the nuclear recoil (NR) scintillation decay time constant in liquid xenon (LXe) using the XMASS-I detector at the Kamioka underground laboratory in Japan. XMASS-I is a large single-phase LXe scintillation detector whose purpose is the direct detection of dark matter via NR which can be induced by collisions between Weakly Interacting Massive Particles (WIMPs) and a xenon nucleus. The inner detector volume contains 832 kg of LXe. 252 Cf was used as an external neutron source for irradiating the detector. The scintillation decay time constant of the resulting neutron induced NR was evaluated by comparing the observed photon detection times with Monte Carlo simulations. Fits to the decay time prefer two decay time components, one for each of the Xe 2 singlet and triplet states, with τ S = 4.3 ± 0.6 ns taken from prior research, τ T was measured to be 26.9 +0.7 -1.1 ns with a singlet state fraction F S of 0.252 +0.027 -0.019 . We also evaluated the performance of pulse shape discrimination between NR and electron recoil (ER) with the aim of reducing the electromagnetic background in WIMP searches. For a 50% NR acceptance, the ER acceptance was 13.7±1.0% and 4.1±0.7% in the energy ranges of 5-10 keV ee and 10-15 keV ee , respectively.

Original languageEnglish
Article numberP12032
JournalJournal of Instrumentation
Volume13
Issue number12
DOIs
Publication statusPublished - 2018 Dec 20
Externally publishedYes

Keywords

  • Noble liquid detectors (scintillation, ionization, double-phase)
  • Particle identification methods
  • Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators)

ASJC Scopus subject areas

  • Mathematical Physics
  • Instrumentation

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