Spatial distribution of muonium-forming electrons in solid argon

An estimate of the dimensions of the spatial distribution of the electrons involved in muonium formation in solid Ar is obtained from the dependence o f the measured muonium asymmetry on applied electric field. A Monte Carlo s imulation of the trajectories of electrons in the vicinity of the positive muon, assuming a simple viscous-flow model of the electron's velocities, gi ves dimensions of a Gaussian electron 'cloud' of 54(8) nm in width, length of 70(12) nm and with its centre displaced 114(10) nm upstream from the muo n. (C) 2000 Elsevier Science B.V. All rights reserved.