EVIDENCE OF IONIZATION ANNEALING UPON HELIUM-ION IRRADIATION OF PRE-DAMAGED FLUORAPATITE

In order to study the behaviour of fluorapatite towards irradiation du e to incorporated alpha-emitters, single crystals of this mineral have been bombarded with 220 keV Pb ions, simulating alpha recoil nuclei, and subsequently irradiated with He ions. The defect concentration mea sured by RES associated with channeling steadily decreases upon He-ion irradiation. By changing the energy of the incident He ions in the ra nge 0.3-3.2 MeV, we have shown that this defect annealing phenomenon c an be ascribed to the electronic energy loss, while the use of B ions which have slightly higher electronic energy loss in the target induce s the opposite effect, i.e., increases the defect concentration. (C) 1 997 Elsevier Science B.V.