Development of an ambient magnetic field compensation system in an accelerator facility for the neutron electric dipole moment measurement

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14487
• 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
• Principal Investigator: Higuchi Takashi 大阪大学, 核物理研究センター, 招へい准教授 (90843772)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 電気双極子モーメント / 加速器 / 磁場安定化 / 時間反転対称性 / CP対称性の破れ / 超冷中性子 / 中性子 / 磁気シールド

Outline of Final Research Achievements

In this project, an environmental magnetic field compensation system was developed for the TUCAN neutron EDM experiment. To achieve the magnetic field environment required for the experiment, a high performance magnetically shielded room (MSR) was developed. However, a background magnetic field of several hundred uT exists at the experiment site due to leakage from the cyclotron accelerator, and there was concern about its negative impact on the MSR shielding performance. In this context, we developed the ambient magnetic field compensation system. First, we obtained a three-dimensional magnetic field distribution from a measurement prior to the construction of the MSR. Based on this data, a simulation was developed that implemented the ambient magnetic field, the MSR, and the compensation coils. The system was designed to reduce the in-plane magnetic flux density in the outermost layer of the MSR by half. A test assembly of the system was completed and a charging test was performed.

Free Research Field

素粒子物理学

Academic Significance and Societal Importance of the Research Achievements

本研究で扱ったような磁気シールドルーム(MSR)は、代表的なものではベルリンPTBのBMSR-2など医療イメージングなどの応用のために、世界の数か所で共用施設として利用されているが、本研究のような加速器からの強い漏れ磁場が存在する場所に設置される例は過去にない。その意味で、本研究は、加速器施設内へのMSR導入の一つのモデルケースを提示した。これは将来の幅広い分野へのMSRの応用のために有意義な知見を与えると考えている。