MUONIUM QUANTUM DIFFUSION IN CRYOCRYSTALS

In this paper we review our recent study on muonium (Mu) diffusion in simplest solids - Van der Waals cryocrystals. We give experimental evi dence for the quantum nature of Mu diffusion in these matters. The res ults are compared with the current theory of quantum diffusion in insu lators. The first direct observation of the T7 power-law for the Mu ho p rate (in solid nitrogen) is taken as confirmation of two-phonon scat tering mechanism. In solid xenon the one-phonon interaction is shown t o be dominant. Muonium diffusion in solid neon is discussed in terms o f band-like motion. Finally, we report a dramatic effect of impurities on Mu quantum diffusion.