FLUORINE PROFILES IN ANTARCTIC METEORITES BY NUCLEAR-REACTION ANALYSIS (NRA)

Terrestrial fIuorine enrichment on Antarctic meteorites can be measure d by detection of gamma-rays from the nuclear reaction F-19(p,alpha ga mma)O-16, which is induced by a scanning proton beam. The technique (N uclear Reaction Analysis by Proton Induced Gamma Emission: PIGME-NRA) allows simultaneous measurement of distribution and concentration with out any chemical sample treatment and is not destructive. By using two detectors (HPGe and NaI) and taking into account the background contr ibution of the main interfering elements, the detection limit is below 10 mu g/g. The information obtained allows to estimate the maximum ex posure duration of meteorites on the Antarctic ice surface.