Measurement of γ rays from 6LiF tile as an inner wall of a neutron-decay detector

J. Koga, S. Ieki, A. Kimura, M. Kitaguchi, R. Kitahara, K. Mishima, N. Nagakura, T. Okudaira, H. Otono, H. M. Shimizu, N. Sumi, S. Takada, T. Tomita, T. Yamada, T. Yoshioka

Research output: Contribution to journalArticlepeer-review


A neutron lifetime measurement conducted at the Japan Proton Accelerator Research Complex (J-PARC) is counting the number of electrons from neutron decays with a time projection chamber (TPC). The γ rays produced in the TPC cause irreducible background events. To achieve the precise measurement, the inner walls of the TPC consist of 6Li-enriched lithium-fluoride (6LiF) tiles to suppress the amount of γ rays. In order to estimate the amount of γ rays from the 6LiF tile, prompt gamma ray analysis (PGA) measurements were performed using germanium detectors. We reconstructed the measured γ-ray energy spectrum using a Monte Carlo simulation with the stripping method. Comparing the measured spectrum with a simulated one, the number of γ rays emitted from the6LiF tile was (2.3+0.7-0.3) × 10-4 per incident neutron. This is 1.4+0.5-0.2 times the value assumed for a mole fraction of the 6LiF tile. We concluded that the amount of γ rays produced from the 6LiF tile is not more twice the originally assumed value.

Original languageEnglish
Article numberP02001
JournalJournal of Instrumentation
Issue number2
Publication statusPublished - Feb 1 2021

All Science Journal Classification (ASJC) codes

  • Mathematical Physics
  • Instrumentation


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