Muon transfer from deuterium to helium

We report on an experiment at the Paul Scherrer Institute, Villigen, Switzerland measuring x rays from muon transfer from deuterium to helium. Both the ground-state transfer via the exotic (d{mu}{sup 3,4}He){sup *} molecules and the excited-state transfer from ({mu}d){sup *} were measured. The use of charge-coupled device detectors allowed x rays from 1.5 keV to 11 keV to be detected with sufficient energy resolution to separate the transitions to different final states in both deuterium and helium. The x-ray peaks of the (d{mu}{sup 3}He){sup *} and (d{mu}{sup 4}He){sup *} molecules were measured with good statistics. For the D{sub 2}+{sup 3}He mixture, the peak has its maximum at E{sub d{mu}}{sub {sup 3}He}=6768{+-}12 eV with full width at half maximum (FWHM) {gamma}{sub d{mu}}{sub {sup 3}He}=863{+-}10 eV. Furthermore, the radiative branching ratio was found to be {kappa}{sub d{mu}}{sub {sup 3}He}=0.301{+-}0.061. For the D{sub 2}+{sup 4}He mixture, the maximum of the peak lies at E{sub d{mu}}{sub {sup 4}He}=6831{+-}8 eV and the FWHM is {gamma}{sub d{mu}}{sub {sup 4}He}=856{+-}10 eV. The radiative branching ratio is {kappa}{sub d{mu}}{sub {sup 4}He}=0.636{+-}0.097. The excited-state transfer is limited by the probability to reach the deuterium ground state, q{sub 1s}. This coefficient was determined for both mixtures: q{sub 1s}{sup {sup 3}He}=68.9{+-}2.7%more » and q{sub 1s}{sup {sup 4}He}=90.1{+-}1.5%.« less