Study of Rare Muon Decay Modes with the Crystal Box

摘要

We report on a search for the lepton family-number-nonconserving decays mu exp + -> e exp + e exp - e exp + , mu exp + -> e exp + gamma , and mu exp + -> e exp + gamma gamma , using the Crystal Box detector at LAMPF. The experiment was run in the stopped muon channel at LAMPF during the winter and summer of 1984. Muons were stopped in the middle of a detector system consisting of a cylindrical drift chamber, a plastic scintillator hodoscope, and a segmented array of sodium iodide crystals. The sodium iodide surrounded the hodoscope and drift chamber. Events consistent with any of the above decays were recorded. The off-line data analysis imposed requirements on the timing, vertex location, and energy and momentum conservation for each event. Radioactive sources, conventional muon decay spectra, and photons from the process pi exp - p -> n gamma and pi exp - p -> n pi exp 0 were used to provide energy calibration and resolution estimates. The inner bremsstrahlung processes mu exp + -> e exp + gamma nu anti nu and mu exp + -> e exp + e exp - e exp + nu anti nu were observed at the expected rates. Details of the detector, the data analysis, and our latest bounds for the branching ratios will be presented. 33 figs. (ERA citation 10:047561)