New Initiative on Search for Charged Lepton Flavor Violation with Highly Intense Muon Source

• Project/Area Number: 18H05231
• Research Category: Grant-in-Aid for Scientific Research (S)
• Allocation Type: Single-year Grants
• Review Section: Broad Section B
• Research Institution: Osaka University
• Principal Investigator: 久野 良孝 大阪大学, 核物理研究センター, 特任教授 (30170020)
• Co-Investigator(Kenkyū-buntansha): 佐藤 朗 大阪大学, 理学研究科, 助教 (40362610) ; 東城 順治 九州大学, 理学研究院, 准教授 (70360592)
• Project Period (FY): 2018-06-11 – 2023-03-31
• Project Status: Granted (Fiscal Year 2022)
• Budget Amount: ¥193,050,000 (Direct Cost: ¥148,500,000、Indirect Cost: ¥44,550,000); Fiscal Year 2022: ¥26,260,000 (Direct Cost: ¥20,200,000、Indirect Cost: ¥6,060,000); Fiscal Year 2021: ¥32,630,000 (Direct Cost: ¥25,100,000、Indirect Cost: ¥7,530,000); Fiscal Year 2020: ¥47,190,000 (Direct Cost: ¥36,300,000、Indirect Cost: ¥10,890,000); Fiscal Year 2019: ¥39,520,000 (Direct Cost: ¥30,400,000、Indirect Cost: ¥9,120,000); Fiscal Year 2018: ¥47,450,000 (Direct Cost: ¥36,500,000、Indirect Cost: ¥10,950,000)
• Keywords: ミューオン / 稀崩壊 / 荷電レプトン / フレーバー / フレーバー変換 / フレーバー転換

Outline of Annual Research Achievements

素粒子物理学のより深い理解のため、標準理論で説明できない新物理現象の探索は最重要課題である。荷電レプトンのフレーパ一転換現象は、標準理論枠内では起きないとされ、かつ多くの新物理の理論が将来観測可能なレベルで発生すると予言しており、新しい物理を発見する最善の物理過程のひとつと考えられている。荷電レプトンのフレーパ一転換で最も重要な過程の一つは、ミューオン電子転換過程である。我々は、東海村のJ-PARC陽子施設において世界最高強度パルスミューオンピームを建設し、ミューオン電子転換過程を現在の上限値を100倍上回る実験精度で探索するCOMET Phase-I実験(J-PARC E21実験)を推進し準備している。この実験は2023年以降に開始することになっている。本研究の目的は、この実験精度を当初の値をさらに数倍向上し測定を確実なものにすることである。
2020年度の実績は以下のようである。COMET実験での主たる検出器は円筒型ガスドリフトチェンバー(CDC)であるが、これは1Tの磁場中に置かれて荷電粒子の運動量を測定する。磁場を発生するために、検出器を覆うことのできる大型の超伝導ソレノイド磁石が必要である。2020年度はこのソレノイド磁石のための冷却容器クライオスタットの端板を作成した。クライオスタットの筒部分は2019年度にすでに製作されており、これらを組み合わせてクライオスタットは完成する。また、CDCは引き続きKEKで宇宙線をつかった性能試験が行われた。位置分解能や検出効率などを調べた。COMET実験に必要な要件を満たしていることがわかった。

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

2020年度には、COMET実験での主たる検出器は円筒型ガスドリフトチェンバー(CDC)であるが、これは1Tの磁場中に置かれて荷電粒子の運動量を測定する。磁場を発生するために、検出器を覆うことのできる大型の超伝導ソレノイド磁石が必要である。2020年度はこのソレノイド磁石のための冷却容器クライオスタットの端板を作成した。クライオスタットの筒部分は2019年度にすでに製作されており、これらを組み合わせてクライオスタットは完成する。また、CDCは引き続きKEKで宇宙線をつかった性能試験が行われた。位置分解能や検出効率などを調べた。COMET実験に必要な要件を満たしていることがわかった。

Strategy for Future Research Activity

今後はまだ新型コロナウイルスの影響で計画どおりに研究が進められるかどうか不明な点は多い。しかし、CDC検出器は要求性能を満たしていることがわかったので、つくばの高エネルギー加速器研究機構から東海村のJ-PARCに移設することになる。移設の前に、CDCの読み出し装置の冷却システムを設置する必要がある。

Assessment Rating

Interim Assessment Comments (Rating)

A-: In light of the aim of introducing the research area into the research categories, the expected progress in research has been made on the whole though a part of it has been delayed.

Research Products

• [Int'l Joint Research] Imperial College London(英国)
• [Int'l Joint Research] UNiversity of Clermont-Ferrant/LPC CAEN/Sorbonne University(フランス)
• [Int'l Joint Research] Techinical University of Dresden(ドイツ)
• [Int'l Joint Research] Institute of High Energy Physics/Sun Yat-Sen University/Nanjing University(中国)
• [Int'l Joint Research] Korean Institute of Advanced Study/Sungkyunkwan university(韓国)
• [Int'l Joint Research]
• [Int'l Joint Research] Imperial College London(英国)
• [Int'l Joint Research] Sorbonne University/University of Clermont-Ferrant/LPC Caen(フランス)
• [Int'l Joint Research] Techical University of Dresden(ドイツ)
• [Int'l Joint Research] Institute of High Energy Physics/Nanjing University/Sun Yat-Syn University(中国)
• [Int'l Joint Research] Joint Institue for Nuclear Research/Budker Institute of Nuclear Physics(ロシア連邦)
• [Int'l Joint Research]
• [Int'l Joint Research] Imperial College London(英国)
• [Int'l Joint Research] Sorbonne University/University of Clermont-Ferrant/LPC Caen(フランス)
• [Int'l Joint Research] Technical University of Dresden(ドイツ)
• [Int'l Joint Research] Institute of High Energy Physics/Nanjing University/Sun Yat-san University(中国)
• [Int'l Joint Research] JINR/BINP(ロシア連邦)
• [Journal Article] GPU-accelerated event reconstruction for the COMET Phase-I experiment (2021)
  • Author(s): Yeo Beomki、Lee MyeongJae、Kuno Yoshitaka
  • Journal Title: Computer Physics Communications Volume: 258 Pages: 107606-107606
  • DOI: 10.1016/j.cpc.2020.107606
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Demonstration of cooling by the Muon Ionization Cooling Experiment (2020)
  • Author(s): MICE collaboration
  • Journal Title: Nature Volume: 578 Pages: 53-59
  • DOI: 10.1038/s41586-020-1958-9
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Probing <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>μ</mml:mi><mml:mi>e</mml:mi><mml:mi>γ</mml:mi><mml:mi>γ</mml:mi></mml:math> contact interactions with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>μ</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>e</mml:mi></mml:math> conversion (2020)
  • Author(s): Davidson S.、Kuno Y.、Uesaka Y.、Yamanaka M.
  • Journal Title: Physical Review D Volume: 102 Pages: 115043-115043
  • DOI: 10.1103/physrevd.102.115043
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Precision experiments with muons and neutrons (2020)
  • Author(s): Kuno Yoshitaka、Pignol Guillaume
  • Journal Title: Comptes Rendus. Physique Volume: 21 Pages: 121-134
  • DOI: 10.5802/crphys.13
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Investigation of the Light Yield Distribution in LYSO Crystals by the Optical Spectroscopy Method for the Electromagnetic Calorimeters of the COMET Experiment (2020)
  • Author(s): Kalinnikov V.、Velicheva E.、Grabtchikov A.、Khodasevich I.、Orlovich V.、Kuno Y.、Sato A.
  • Journal Title: Nonlinear Phenomena in Complex Systems Volume: 23 Pages: 374-385
  • DOI: 10.33581/1561-4085-2020-23-4-374-385
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Commissioning of the Cylindrical Drift Chamber for the COMET experiment (2020)
  • Author(s): Moritsu Manabu、KUNO YOSHITAKA、Matsuda Yugo、Nakazawa Yu、Ohta Saki、Sakamoto Hideyuki、Sato Akira、Wong Ming Liang、Wong TingSam、Wu Chen、Yoshida Hisataka、Jiang Xiaoshan、Li Hai-bo、Nakatsugawa Yohei、Zhang Jie
  • Journal Title: PoS EPS-HEP2019 Volume: 1 Pages: 128-128
  • DOI: 10.22323/1.364.0128
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Radiation hardness study for the COMET Phase-I electronics (2020)
  • Author(s): Y. Nakazawa, M. Moritsu et al.
  • Journal Title: Nuclear Instruments and Methods in Physics Research Section A Volume: 955 Pages: 163247-163247
  • DOI: 10.1016/j.nima.2019.163247
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Radiation study of FPGAs with neutron beam for COMET Phase-I (2019)
  • Author(s): Nakazawa Yu、Fujii Yuki、Hamada Eitaro、Lee MyeongJae、Miyazaki Yuta、Sato Akira、Ueno Kazuki、Yoshida Hisataka、Zhang Jie
  • Journal Title: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 印刷中 Pages: 351-352
  • DOI: 10.1016/j.nima.2018.10.130
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Selecting μ→e conversion targets to distinguish lepton flavour-changing operators (2019)
  • Author(s): S. Davidson, Y. Kuno, M. Yamanaka
  • Journal Title: Physics Letters B Volume: 790 Pages: 380-388
  • DOI: 10.1016/j.physletb.2019.01.042
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Momentum distribution of the electron pair from the charged lepton flavor violating process μe→ee in muonic atoms with a polarized muon (2019)
  • Author(s): Kuno Yoshitaka、Sato Joe、Sato Toru、Uesaka Yuichi、Yamanaka Masato
  • Journal Title: Physical Review D Volume: 100 Pages: 075012-075012
  • DOI: 10.1103/physrevd.100.075012
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Spin-dependent μ→e conversion on light nuclei (2018)
  • Author(s): Sacha Davidson, Yoshitaka Kuno, Albert Saporta
  • Journal Title: The European Physical Journal C Volume: C78 Pages: 109-109
  • DOI: 10.1140/epjc/s10052-018-5584-8
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Muon capture reaction on Mo100 to study the nuclear response for double-β decay and neutrinos of astrophysics origin (2018)
  • Author(s): Hashim I. H.、Ejiri H.、Shima T.、Takahisa K.、Sato A.、Kuno Y.、Ninomiya K.、Kawamura N.、Miyake Y.
  • Journal Title: Physical Review C Volume: 97 Pages: 014617-014617
  • DOI: 10.1103/physrevc.97.014617
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Improved analysis for μ-e-->e-e- in muonic atoms by photonic interaction (2018)
  • Author(s): Yuichi Uesaka, Yoshitaka Kuno, Joe Sato, Toru Sato, Masato Yamanaka
  • Journal Title: Physical Review Volume: 97 Pages: 015017-015017
  • DOI: 10.1103/physrevd.97.015017
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] A proposal of a New Charged Lepton Flavor Violation Experiment: μ-e- → e-e- in muonic atom (2018)
  • Author(s): Sato Joe、UESAKA Yuichi、KUNO YOSHITAKA、Sato Toru、Yamanaka Masato
  • Journal Title: PoS Nufact2017 Volume: 1 Pages: 125-125
  • DOI: 10.22323/1.295.0125
  • Peer Reviewed
• [Journal Article] COMET Phase-I Technical Design Report (2018)
  • Author(s): G. Adamov et al. (COMET collaboration)
  • Journal Title: arXiv:1812.09018 Volume: 1 Pages: 1-1
  • Open Access / Int'l Joint Research
• [Presentation] COMET-CDCの宇宙線試験による性能評価 (2020)
  • Author(s): 樋口雄也、中津川洋平、森津学、久野良孝、吉田学立、青木正治、佐藤朗、中沢遊、Wu Chen、Sun Siyuan、他COMET-CDCグループ
  • Organizer: 日本物理学会
• [Presentation] Study of Gas Gain Saturation in COMET CDC (2020)
  • Author(s): Sun Siyuan、Yohei Nakatsugawa、Yuya Higuchi、Masaharu Aoki、Yoshitaka Kuno、Manabu Moritsu、Yu Nakazawa、Akira Sato、Wu Chen、Hisataka Yoshida、and the COMET-CDC group
  • Organizer: 日本物理学会
• [Presentation] COMET実験のトリガー検出器に用いる新型SiPMの中性子耐性評価試験 (2020)
  • Author(s): 佐藤良紀、松本岳、上野一樹、青木正治、東城順治、三原智、吉田学立、藤井祐樹
  • Organizer: 日本物理学会
• [Presentation] Study of Gas Gain Saturation for Cylindrical Drift Chamber in COMET Phase-I with cosmic-ray test (2020)
  • Author(s): un Siyuan、Masaharu Aoki、Yuya Higuchi、Yoshitaka Kuno、Manabu Moritsu、Yohei Nakatsugawa、Yu Nakazawa、Akira Sato、Wu Chen、Hisataka Yoshida、and the COMET-CDC group
  • Organizer: 日本物理学会
• [Presentation] HULを用いた8GeV extinction 試験におけるDAQシステムの開発 (2020)
  • Author(s): 樋口雄也、三原智、五十嵐洋一、西口創、上野一樹、深尾祥紀、藤井祐樹、庄子正剛、東城順治、本多良太郎、吉田学立、野口恭平、中沢遊、Wu Chen、池田史
  • Organizer: 日本物理学会
• [Presentation] Muon to Electron Conversion in Muonic Atom (2020)
  • Author(s): Yoshitaka Kuno
  • Organizer: CTS Dark Physics Workshop
  • Invited
• [Presentation] Overview of Muon Physics (2019)
  • Author(s): Yoshitaka Kuno
  • Organizer: 2nd International Workshop on EMUs Multidisciplinary Applications
  • Invited
• [Presentation] Searching for Muon to Electron Conversion in a Muonic Atom (2019)
  • Author(s): Yoshitaka Kuno
  • Organizer: 2nd IBS Conference on Dark World
  • Invited
• [Presentation] ４．Muon to Electron Conversion with COMET at J-PARC (2019)
  • Author(s): Yoshitaka Kuno
  • Organizer: The 2019 International Workshop on Baryon and Lepton Number Violation (BLV2019)
  • Invited
• [Presentation] Pulsed Muon Beam Experiments (2019)
  • Author(s): Yoshitaka Kuno
  • Organizer: The 21st International Workshop on Neutrinos from Accelerators (NuFACT2019)
  • Invited
• [Presentation] Overview of Charged Lepton Flavour Violation (2019)
  • Author(s): Yoshitaka Kuno
  • Organizer: The 19th Lomonosov Conference
  • Invited
• [Presentation] Search for Charged Lepton Flavour Violation with Muons (2019)
  • Author(s): Yoshitaka Kuno
  • Organizer: International Workshop on Anomalies
  • Invited
• [Presentation] ８．Search for Muon to electron conversion J-PARC; The Current Status of COMET Experiment (2019)
  • Author(s): Chen Wu
  • Organizer: The 3rd International Conference on Charged Lepton Flavor Violation (CLFV2019)
  • Invited
• [Presentation] Physics Prospects with Muons (2019)
  • Author(s): Yoshitaka Kuno
  • Organizer: The Open Symposium on 2020 Update of European Strategy for Particle Physics
  • Invited
• [Presentation] COMET experiment (2019)
  • Author(s): Hisataka Yoshida
  • Organizer: KPS-JPS joints symposium
  • Invited
• [Presentation] Experimental Prospects of Charged Lepton Flavour Violation (2019)
  • Author(s): Yoshitaka Kuno
  • Organizer: International Workshop on Prospects of Neutrino Physics
  • Invited
• [Presentation] COMET-CDC検出器のフル稼働と今後の計画 (2019)
  • Author(s): 吉田 学立
  • Organizer: 日本物理学会 第75回年次大会
• [Presentation] COMET-CDC検出器における宇宙線試験の解析(2) (2019)
  • Author(s): 太田 早紀
  • Organizer: 日本物理学会 第75回年次大会
• [Presentation] COMET実験のための新型SiPMの中性子耐性評価試験 (2019)
  • Author(s): 佐藤 良紀
  • Organizer: 日本物理学会2019年秋季大会
• [Presentation] COMET-CDC検出器の現状と今後の計画 (2019)
  • Author(s): 吉田 学立
  • Organizer: 日本物理学会2019年秋季大会
• [Presentation] COMET-CDC検出器における宇宙線試験の解析 (2019)
  • Author(s): 太田 早紀
  • Organizer: 日本物理学会2019年秋季大会
• [Presentation] COMET Experiment (2018)
  • Author(s): H. Yoshida
  • Organizer: Sympoisum for Muon and Neutrino Physics 2018
  • Int'l Joint Research / Invited
• [Presentation] Search for Muon to Electron Conversion at J-PARC (2018)
  • Author(s): Wu Chen
  • Organizer: Future Programme of Intensity Frontier of Particle Physics at China's High Power Hadron Accelerators 1st Conference
  • Int'l Joint Research / Invited
• [Presentation] General features of LFV experiments with muons (2018)
  • Author(s): Y. Kuno
  • Organizer: The 15th International Workshop on Tau Lepton Physics (at Amsterdam, Netherlands,
  • Int'l Joint Research / Invited
• [Presentation] COMET experiment ; search for muon to electron conversion (2018)
  • Author(s): H. Yoshida
  • Organizer: New Trends in High-Energy Physics
  • Int'l Joint Research / Invited
• [Presentation] Search for Muon to Electron Conversion in a Muonic Atom (2018)
  • Author(s): Y. Kuno
  • Organizer: Physics of muonium and related topics
  • Int'l Joint Research / Invited
• [Presentation] Search for Charged Lepton Flavor Violation with Muons (2018)
  • Author(s): Y. Kuno
  • Organizer: 5th International Workshop on “ Dark Matter Dark Energy, and Matter Antimatter Asymmetry
  • Int'l Joint Research / Invited
• [Presentation] The Design of Muon Production Target and The Application of FFAG (2018)
  • Author(s): Wu Chen
  • Organizer: Future Programme of Intensity Frontier of Particle Physics at China's High Power Hadron Accelerators 2nd Conference
  • Int'l Joint Research / Invited
• [Presentation] Background Study of the COMET Experiment (2018)
  • Author(s): Wu Chen
  • Organizer: Future Programme of Intensity Frontier of Particle Physics at China's High Power Hadron Accelerators 2nd Conference
  • Int'l Joint Research / Invited
• [Presentation] Radiation study of FPGAs with neutron beam for the COMET Phase-I (2018)
  • Author(s): Y. Nakazawa
  • Organizer: 14th Pisa Meeting on Advanced Detectors
  • Int'l Joint Research
• [Presentation] COMET-CDC の宇宙線を用いた性能評価試験(5) (2018)
  • Author(s): 吉田学立
  • Organizer: 日本物理学会2018 年秋季大会
• [Presentation] COMET-CDC における宇宙線試験のアライメント解析(2) (2018)
  • Author(s): 松田悠吾
  • Organizer: 日本物理学会2018 年秋季大会
• [Presentation] COMET-CDC のためのトリガーシステム開発状況 (2018)
  • Author(s): 中沢遊
  • Organizer: 日本物理学会2018 年秋季大会
• [Presentation] Tracking Finding for COMET experiment with Convolution Neural Network (2018)
  • Author(s): TingSam Wong
  • Organizer: 日本物理学会2018 年秋季大会
• [Presentation] Track Fitting of COMET CDC (2018)
  • Author(s): Wu Chen
  • Organizer: 日本物理学会2018 年秋季大会
• [Presentation] COMET-CDC の宇宙線を用いた位置分解能の評価試験 (2018)
  • Author(s): 太田早紀
  • Organizer: 日本物理学会第74 回年次大会（2019 年）
• [Presentation] COMET-CDC における宇宙線試験の解析 (2018)
  • Author(s): 松田悠吾
  • Organizer: 日本物理学会第74 回年次大会（2019 年）
• [Presentation] The New Study for Phase-II of COMET Experiment (2018)
  • Author(s): Yao Weichao
  • Organizer: 日本物理学会第74 回年次大会（2019 年）
• [Presentation] COMET Phase-I のための飛跡検出器情報を用いたオンライントリガーシステムの開発 状況 (2018)
  • Author(s): 中沢遊
  • Organizer: 日本物理学会第74 回年次大会（2019 年）
• [Presentation] Result for communication test of online trigger system of Cylindrical Drift Chamber for COMET Phase-I experiment (2018)
  • Author(s): Tai Thanh Chau
  • Organizer: 日本物理学会第74 回年次大会（2019 年）
• [Presentation] COMET Phase-I CDC のためのSlow Control System の開発状況(2) (2018)
  • Author(s): 吉田学立
  • Organizer: 日本物理学会第74 回年次大会（2019 年）
• [Presentation] 素粒子と原子物理の融合が拓く新たなミュー粒子物理のフロンティアまとめ (2018)
  • Author(s): 久野良孝
  • Organizer: 日本物理学会第74 回年次大会（2019 年）
• [Remarks] COMET Web page
  • URL: http://comet.kek.jp/Introduction.html
• [Remarks] 久野研究室
  • URL: http://www-kuno.phys.sci.osaka-u.ac.jp
• [Remarks] COMET MU-E CONVERSION
  • URL: http://comet.kek.jp/Introduction.html