Comparison of Muon Capture in Light and in Heavy Nuclei

摘要

We have recently completed an experimental study at TRIUMF of muon capture in the following elements, N, Al, Si, Ca, Fe, Ni, I, Au, and Bi. We detected the nuclear gamma rays emitted by the product nuclei after muon capture. The energy of the gamma ray identifies the source nuclide, and thus the reaction which has occurred. Our data are of better quality, and more comprehensive than any other data set in the literature. The (μ?,vn) reaction is always dominant. In light nuclei, reactions such as (μ?,vpn) and (μ?,pn) can occur, but not for heavy nuclei. However the reverse is true for reactions such as (μ?,3n) and (μ?,v4n), which are very rare in light nuclei, but easily detected in heavy elements. We shall discuss how such information can be useful in calculations of neutrino-nucleus interactions, and of electron-capture in supernovae.