The precise measurement of the μ+ lifetime

S. N. Nakamura, D. Tomono, Y. Matsuda, G. Mason, M. Iwasaki, K. Ishida, T. Matsuzaki, I. Watanabe, S. Sakamoto, K. Nagamine

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


The lifetime of the positive muon (τμ+) can be directly associated with the Fermi Coupling Constant (GF), which is one of the most basic parameters of the Standard Model. However, the current experimental accuracy of the τμ+ is ∼30 ppm and it has not been improved for more than 15 years. We propose a new experiment for a pulsed muon facility such as RIKEN-RAL to measure the muon lifetime with multi-decay per one time window method. The advantage of our setup, no time window limitation, enables us to test the exponential decay law (EDL) in the long decay time region at the same time. The preliminary analysis set a new upperlimit for the EDL deviation in the muon decay. We accumulated ∼1010 muon decays and analysis is in progress.

Original languageEnglish
Pages (from-to)445-450
Number of pages6
JournalHyperfine Interactions
Issue number1-4
Publication statusPublished - 2001 Dec 1


  • Fermi coupling constant
  • Lifetime
  • Muon
  • Standard model

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry


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