By measuring gas release during isothermal and ramp heating, the diffusion of isolated He atoms could be determined at homologous temperatures greater than 0.6. The results could be described by:

D (cm2/s) = 1.0 x 10-1 exp[-1.70(eV)/kT]

V.Sciani, P.Jung: Radiation Effects, 1983, 78[1-4], 87-99