1. A measurement of the scintillation decay time constant of nuclear recoils in liquid xenon with the XMASS-I detector
- Author
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B. D. Xu, Atsushi Takeda, Shogo Nakamura, G. Kanzaki, Lee Min-Kie, K. Kobayashi, M. Miyasaka, Ken-Ichi Fushimi, Hiroyuki Sekiya, Nam Young Kim, Y. Fukuda, Y. Takeuchi, K.B. Lee, Masaki Yamashita, O. Takachio, B. S. Yang, Takatoshi Suzuki, Yasuhiro Kishimoto, Kimiaki Masuda, N. Oka, K. Kanzawa, Koichi Ichimura, Yong Hamb Kim, Shigeki Tasaka, Yoshitaka Itow, Shigetaka Moriyama, K. Martens, Yoshihiro Suzuki, M. Kobayashi, Ko Abe, K. Nishijima, Y. D. Kim, Kentaro Miuchi, Katsuki Hiraide, Masayuki Nakahata, Hiroshi Ogawa, and Katsuhiko Sato
- Subjects
Physics - Instrumentation and Detectors ,Physics::Instrumentation and Detectors ,FOS: Physical sciences ,chemistry.chemical_element ,Noble liquid detectors (scintillation, ionization, double-phase) ,01 natural sciences ,High Energy Physics - Experiment ,Nuclear physics ,High Energy Physics - Experiment (hep-ex) ,Particle identification methods ,Xenon ,0103 physical sciences ,Nuclear Experiment (nucl-ex) ,010306 general physics ,Nuclear Experiment ,Instrumentation ,Mathematical Physics ,Physics ,Scintillation ,010308 nuclear & particles physics ,Detector ,Instrumentation and Detectors (physics.ins-det) ,Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators) ,Decay time ,chemistry ,High Energy Physics::Experiment ,Constant (mathematics) - 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 $\tau_{S}$ = 4.3$\pm$0.6 ns taken from prior research, $\tau_{T}$ 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${\pm}$1.0\% and 4.1${\pm}$0.7\% in the energy ranges of 5--10 keV$_{\rm ee}$ and 10--15 keV$_{\rm ee}$, respectively., Comment: 18 pages, 10 figures
- Published
- 2018