Experimental study of {mu}-atomic and {mu}-molecular processes in pure helium and deuterium-helium mixtures

We present experimental results of {mu}-atomic and {mu}-molecular processes induced by negative muons in pure helium and helium-deuterium mixtures. The experiment was performed at the Paul Scherrer Institute (Switzerland). We measured relative intensities of muonic x-ray K series transitions in ({mu}{sup 3,4}He){sup *} atoms in pure helium as well as in helium-deuterium mixtures. The d{mu}{sup 3}He radiative decay probabilities for two different helium densities in D{sub 2}+{sup 3}He mixture were also determined. Finally, the q{sub 1s}{sup He} probability for a d{mu} atom formed in an excited state to reach the ground state was measured and compared with theoretical calculations using a simple cascade model.