Advance in a Search for Muon-Electron Conversion in a Nuclear Field with an Innovative Experimental Method

2020 Fiscal Year Final Research Report

• Project/Area Number: 17H01128
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Osaka University
• Principal Investigator: Aoki Masaharu 大阪大学, 理学研究科, 教授 (80290849)
• Co-Investigator(Kenkyū-buntansha): 三宅 康博 大学共同利用機関法人高エネルギー加速器研究機構, 物質構造科学研究所, 特別教授 (80209882) ; 清矢 良浩 大阪市立大学, 大学院理学研究科, 教授 (80251031)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 荷電レプトン・フレーバ非保存 / ミュー粒子 / 稀崩壊

Outline of Final Research Achievements

A muon to electron conversion (mu-e conversion) is heavily suppressed in the Standard Model of particle physics (SM), but in many new frameworks with physics beyond the SM the existence of the process with sizable branching ratio is expected. The experimental research for the mu-e conversion is very important and urgent. We aimed to search for the mu-e conversion, and developed a novel experimental technique using a high-purity high-intensity pulsed proton beam from J-PARC RCS. In order to realize a physics measurement as early as possible, the improvements of a high-burst tolerance radiation detector and the development of a new beam-profile monitor specially designed for the pulsed beam were performed. We have prepared for the physics data taking once the beam line becomes available.

Free Research Field

素粒子実験

Academic Significance and Societal Importance of the Research Achievements

我々は、mu-e転換過程探索実験の重要性と、物理測定の早期実現やそれに続く段階的な物理感度の向上を強く訴え、実験の実現に向けて具体的に行動してきた。近年国内外のミュー粒子基礎実験分野が大きく活性化されており、我々の活動が与えた影響は非常に大きいと考える。
本研究を通して、博士号2件、修士号5件を輩出した。博士号取得者はmu-e転換過程探索実験の分野で国際的に活躍しており、ミュー粒子研究分野の国際的な発展と若手人材の育成に大きく寄与した。