Measurement of ambient neutrons in an underground laboratory at Kamioka Observatory and future plan

Keita Mizukoshi, Ryosuke Taishaku, Keishi Hosokawa, Kazuyoshi Kobayashi, Kentaro Miuchi, Tatsuhiro Naka, Atsushi Takeda, Masashi Tanaka, Yoshiki Wada, Kohei Yorita, Sei Yoshida

Research output: Contribution to journalConference articlepeer-review

Abstract

Ambient neutrons are one of the most serious backgrounds for underground experiments in search of rare events. The ambient neutron flux in an underground laboratory of Kamioka Observatory was measured using a 3He proportional counter with various moderator setups. Since the detector response largely depends on the spectral shape, the energy spectra of the neutrons transported from the rock to the laboratory were estimated by Monte-Carlo simulations. The ratio of the thermal neutron flux to the total neutron flux was found to depend on the thermalizing efficiency of the rock. Thus, the ratio of the count rate without a moderator to that with a moderator was used to determine this parameter. Consequently, the most-likely neutron spectrum predicted by the simulations for the parameters determined by the experimental results was obtained. The result suggests an interesting spectral shape, which has not been indicated in previous studies. The total ambient neutron flux is [1]. In this paper, we explain our method of the result and discuss our future plan.

Original languageEnglish
Article number012247
JournalJournal of Physics: Conference Series
Volume1468
Issue number1
DOIs
Publication statusPublished - 2020 Mar 20
Event16th International Conference on Topics in Astroparticle and Underground Physics, TAUP 2019 - Toyama, Japan
Duration: 2019 Sep 92019 Sep 13

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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