Determining the ejection rate and energy spectrum of protons after muonic capture on aluminum
Quirk, John R.
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Observation of neutrinoless muon-to-electron conversion in the presence of a nucleus would be unambiguous evidence of physics Beyond the Standard Model. Two experiments, COMET at J-PARC and Mu2e at Fermilab, will search for this process in the next few years. These experiments will provide upper-limits on this branching ratio up to 10,000 times better than previously published. COMET/Mu2e developed a joint venture, the AlCap Experiment, to measure particle emission spectra from muonic interactions in several materials. Targeting a significant source of damage and background hits in COMET/Mu2e detectors, AlCap measured the charged particle and neutron spectra following nuclear capture on the candidate target materials aluminum and titanium, as well as in many structural and shielding materials capable of producing other backgrounds. Additionally, COMET/Mu2e are exploring schemes for determining the number of in-target muon stops via AlCap’s measurement of the photon spectra produced by both atomic and nuclear capture. AlCap performed three data-taking campaigns between 2013 and 2015 at the Paul Scherrer Institut in Switzerland, each geared towards different measurements of photon, neutron, and charged particle emission due to interactions of muons stopping in materials. During the final campaign, AlCap collected heavy charged particle data. In this thesis, I present a measurement of the proton emission spectrum for an aluminum target from the most recent campaign and compare it with the results of previous and current parallel analyses. I also discuss the impact on Mu2e.
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