Measurement of muon mass by precision laser spectrpscopy

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K13944
• 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: Okayama University
• Principal Investigator: Imai Yasutaka 岡山大学, 異分野基礎科学研究所, 特任助教 (30888342)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 素粒子実験 / ミューオニウム / 高出力光源 / Yb添加ファイバ増幅器

Outline of Final Research Achievements

We developed a Yb-doped fiber amplifier as a fundamental laser source of deep ultraviolet laser for spectroscopy of the 1S-2S transition in muonium. The amplification of the fiber amplifier is close to that of the simulation design, and the output power was successfully increased up to several watts.
We also conducted spectroscopy of the 1S-2S transition in muonium using a pulsed laser at the muon beamline at J-PARC. We succeeded to observe the spectrum of the 1S-2S transition with a signal rate about 60 times stronger than that of previous studies. In addition, we observed the other hyperfine transition line of the 1S-2S transition, which was difficult to observe in previous studies due to insufficient signal rate.

Free Research Field

素粒子、原子核、宇宙線および宇宙物理に関連する実験

Academic Significance and Societal Importance of the Research Achievements

ミューオニウム1S-2S遷移のレーザー分光によるミューオニウムに関わる基礎物理定数の精密測定は，素粒子標準理論の検証，また標準理論を超える新たな物理の探査にもつながる．
また，Yb添加ファイバ光増幅器は高出力かつ高品質な空間モードが実現可能なため，その開発のノウハウを得ることは今後のレーザー実験の光源開発につながる．