Ultracold neutron storage experiment with the pulsed ultracold neutron source and a cyclically operating valve

• Project/Area Number: 18K13563
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Osaka University (2019); Nagoya University (2018)
• Principal Investigator: Imajo Sohei 大阪大学, 核物理研究センター, 特任研究員 (10796486)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000); Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
• Keywords: 超冷中性子 / 中性子光学 / 材料工学 / 装置開発 / シミュレーション / センサー / 中性子電気双極子能率 / 貯蔵実験

Outline of Final Research Achievements

We attempted to store pulsed ultracold neutrons (UCN) with a cyclically opening valve synchronized with the pulse arrival in order to increase the number density of UCN in the storage experiments such as the searches of the neutron electric dipole moment or the measurements of the neutron lifetime. However, we abandoned the demonstration experiment because of the great negative results of our simulation which predicted the low or non-increase of the density. We examined the cause of the decrease. Besides, we have developed cyclically opening valves for expected experiments. The valve can open or close in at least 12-ms duration and has strong durability enough to use in long-term research and development. The opening duration and period can be controlled arbitrarily.

Academic Significance and Societal Importance of the Research Achievements

基礎物理実験や材料開発への将来的な応用を見据えてパルス状に生成されるガス状の低速中性子を容器内により多く貯蔵することを試みた。しかしながら実用になる前提条件が非常に厳しく、一般的には貯蔵するよりもパルスをより切り詰めて利用した方がよいという結果が示唆された。

Research Products

• [Journal Article] Ultracold Neutron Time Focusing Experiment and Performance Evaluation of an Improved UCN Rebuncher at J-PARC/MLF (2020)
  • Author(s): S. Imajo, Y. Iwashita, K. Mishima, M. Kitaguchi, H. M. Shimizu, T. Ino, S. Yamashita, K. Hirota, F. Goto, Y. Fuwa, R. Katayama
  • Journal Title: JPS Conference Proceedings Volume: -
  • Peer Reviewed
• [Presentation] 超冷中性子リバンチャー2号機の性能評価実験結果 (2019)
  • Author(s): 今城想平, 岩下芳久, 三島賢二, 北口雅暁, 清水裕彦, 猪野隆, 山下了, 広田克也, 後藤文也, 不破康裕, 片山領
  • Organizer: 日本物理学会 2019 年秋季大会
• [Presentation] Ultracold Neutron Time Focusing Experiment and Performance Evaluation of an Improved UCN Rebuncher at J-PARC/MLF (2019)
  • Author(s): S. Imajo, Y. Iwashita, K. Mishima, M. Kitaguchi, H. M. Shimizu, T. Ino, S. Yamashita, K. Hirota, F. Goto, Y. Fuwa, R. Katayama
  • Organizer: The 3rd J-PARC Symposium
  • Int'l Joint Research