Photon asymmetry measurement in radiative muon capture on 40Ca

A. Pouladdej, T. P. Gorringe, M. D. Hasinoff, A. J. Larabee, A. J. Noble, C. J. Virtue, D. H. Wright, G. Azuelos, B. C. Robertson

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3 Scopus citations


A measurement of the photon asymmetry (αγ) in radiative muon capture RMC on 40Ca has been carried out at TRIUMF. Negative muons were stopped in a 40Ca target and the resulting RMC photons were then converted by a 5-cm thick NaI detector placed immediately in front of our main NaI detector, a cylindrical crystal of diameter 46 cm and depth 51 cm. The data sample consisted of 5200 high-energy (57 MeV<E γ <95 MeV) RMC photon candidates. Our measured value for the energy-averaged photon asymmetry is αγ = 1.00±0.23. The extracted values for the induced pseudoscalar coupling constant (gP) based on this photon asymmetry measurement are g P/gA <8.0, utilizing the impulse approximation IA model, and gP/gA <14.5 in terms of the modified impulse approximation (MIA) model. The two extracted values, although both consistent with the Goldberger-Treiman value of gP/gA ≈ 7, are considerably different, indicating a significant theoretical model dependency.

Original languageEnglish
Article number034605
Pages (from-to)346051-3460514
Number of pages3114464
JournalPhysical Review C - Nuclear Physics
Issue number3
StatePublished - Sep 2003

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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