Muon transfer from deuterium to helium -: art. no. 022712

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 (dmu(3,4)He)(*) molecules and the excited-state transfer from (mud)(*) 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 (dmu(3)He)(*) and (dmu(4)He)(*) molecules were measured with good statistics. For the D-2+He-3 mixture, the peak has its maximum at (EdmuHe)-He-3=6768+/-12 eV with full width at half maximum (FWHM) Gamma(dmu)(3)He=863+/-10 eV. Furthermore, the radiative branching ratio was found to be kappa(dmu)(3)He=0.301+/-0.061. For the D-2+He-4 mixture, the maximum of the peak lies at (EdmuHe)-He-4=6831+/-8 eV and the FWHM is Gamma(dmu)(4)He=856+/-10 eV. The radiative branching ratio is kappa(dmu)(4)He=0.636+/-0.097. The excited-state transfer is limited by the probability to reach the deuterium ground state, q(1s). This coefficient was determined for both mixtures: q(1s)(3)He=68.9+/-2.7% and q(1s)(4)He=90.1+/-1.5%.