Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Arts and Sciences


Physics and Astronomy

First Advisor

Dr. Tim Gorringe


The MuSun experiment will determine the muon capture rate on deuterium (µ− + dn + n + νµ) from the doublet hyperfine spin state, Λd, of muonic deuterium to a precision of 1.5%. Muon capture can occur from either the quartet or doublet state of the 1S orbital of the µd atom; however, the V-A nature of the process strongly suppresses the rate of capture from the quartet state, Λq. Muons in ultrapure deuterium gas may also catalyze d+d3He+n fusion through the formation of dµd molecules.

Using neutron data from run 6 of the MuSun experiment, a new method is developed for determining the relative capture rates from the two hyperfine spin states, Λqd. This method takes advantage of several improvements which were new for run 6 including a reduced beam-dependent neutron background, thanks to the move from the πE3 to the πE1 beamline at Paul Scherrer Institute, and improved energy resolution of the TPC due to the installation of new cryogenic pre-amplifiers. These improvements also allow for a new determination of the relative rates of molecular ddµ formation from the quartet and doublet atomic states, λqd, as well as the quartet to doublet hyperfine transition rate, λqd, which were previously determined by Raha [1] using neutron data from MuSun run 4.

An upper bound is placed on the relative capture rate of Λqd < 0.275(90%cl.). The relative molecular formation rate is found to be λqd = 103.2 ± 1.9(stat.) ± 2.50(syst.), and the hyperfine transition rate is found to be 34.74 ± 0.21(stat.) ± 0.044(syst.).

Digital Object Identifier (DOI)

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Nuclear Commons