Effect of gold ion irradiation on helium migration in fluoroapatites investigated with nuclear reaction analysis

In the context of nuclear waste storage, the knowledge of the effect of irradiation on the diffusion of helium produced by α-decays in apatites is an important issue. The analysis of implanted 3He diffusion for two compositions was carried out with the 3He(d,p)4He nuclear reaction by using a deuteron milli- or micro-beam. Upon 163-MeV Au-ion irradiation, a significant fraction of 3He atoms migrated towards the surface below which they were trapped, whereas a proportion of 3He atoms remained trapped in the end-of-range region. Moreover, a clear helium loss was determined. These radiation-induced migration effects are enhanced in Ca10(PO4)6F2 compared with the Ca4Nd6(SiO4)6F2.