µ+ Diffusion in Metals

Until about 1983, the following cartoon was fairly representative of the world's understanding of how a screened interstitial positive muon diffuses in a metallic crystal:

This picture is now considered very naive, but at that time it was based upon the following sort of data showing the temperature dependence of the µ+ relaxation rate in various metals:


Here the relaxation rate decreases where the muon hop rate increases, due to "motional narrowing" (the averaging effect of motion among many sites with slightly different local magnetic fields due to randomly oriented nuclear dipole moments).

Jess H. Brewer
Last modified: Mon Dec 1 09:45:18 EST ±