Muonium formation at keV energies

摘要

Charge differentiation in mu(+) or muonium (Mu) as a consequence of the slowing down of mu+ in matter is of fundamental interest in the muSR method. It is also of relevance for understanding the moderation process of mu(+) in van der Waals solids like s-Ne, s-Ar or s-N-2, which are the most suitable materials to generate epithermal mu(+) serving as a source for low-energy mu(+) (LE-mu(+)) beams. The LE-mu(+) beam at the Paul Scherrer Institut (PSI) allows us to study the formation of Mu at low implantation energies (0.5-30 keV) in insulators and semiconductors. These investigations may help to clarify the interaction between the mu(+) and the electrons of its ionisation track since the number of track electrons can be tuned by varying the implantation energy. We present the first results of LE-muSR investigations on thin van der Waals solids (s-Ar, s-Xe), fused quartz (SUPRASIL) and a quartz crystal, where the mu(+) and Mu fractions were measured as a function of the implantation energy. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 7]