Investigation of charge transfer from excited muonic hydrogen atoms to argon

A method is proposed for investigating muon transfer from excited muonic hydrogen atoms to an element Z>2, and is applied to argon measurements. It makes use of a comparison between the muonic x-ray intensity patterns of the Lyman series of this element measured in mixtures with and without hydrogen. The analysis of the data taken in two gas mixtures H₂ + Ar at 15 bar with argon concentrations of 2% (0.3%), yields consistent results. In both mixtures, two thirds of the prompt argon x rays proceed from transfer from excited μp^* states. The Coulomb capture ratio determined in both mixtures yields a mean value of A(H₂,Ar) = 0.21(2), and agrees with the corresponding pionic ratio.