To study Mu diffusion in temperature regimes where the hop rate is slower, one needs a sample composed of a nearly pure spinless isotope such as 136Xe.
Oddly enough, muonium relaxes fairly fast even in the absence of nuclear moments, especially above about 120K, where the data suggest Mu relaxation by paramagnetic ions (probably those created in its radiolysis track).
Data taken in natural s-Xe are compared with those shown here to determine (crudely) what fraction of the Mu relaxation rate can be attributed to nuclear moments and quantum diffusion.