If we look at the atomic positions in a single crystal sample with a diamond like lattice, there exist directions along which there are long hexagonal "tubes" (I'm not sure if these have a proper term).
This happens in silicon for example. Now if a hydrogen atom was inserted in the material, it would be too large and just get trapped in the 'matrix' of the silicon and present a defect in the material.
If instead I took a proton and muon in a bound "muonic hydrogen" state, the bohr radius which goes like 1/m would be ~ 200x's smaller. Due to being neutral, small, and tightly bound (a binding energy > 2.5 keV), I am tempted to view it almost like a large neutron.
My question is:
Due to its much smaller size, could such a 'large neutron' pass freely through a crystal along one of these tubes?
Could one eliminate trapped hydrogen in a crystal by making it "mobile" in this fashion by putting the sample in a muon beam of low enough energy that it won't damage the crystal structure but still create 'muonic hydrogen'?