F-19(p,p 'gamma)F-19 and O-18(p,gamma)F-19 gamma-ray interferences studiedon liquids

The interference effects for the 110 and 197 keV gamma-ray lines of the nuc lear reactions F-19(p,p'gamma)F-19 and O-18(p,gamma)F-19 were studied quant itatively. For this, thick liquid targets were examined by proton induced g amma-ray emission (PIGE) using an external proton beam of 3.4 MeV energy. S everal grades of dilutions were prepared from 76.3% O-18 enriched H2O and f rom 1000 ppm F standard NaF solution. From this, a data base was obtained i n order to extrapolate the 110 and 197 keV gamma-ray yields of the O-18(p,g amma)F-19 reaction for a target of water containing 0.2% O-18. As a result it was obtained that, for fluorine in oxygen-rich materials, the reaction F -19(p,p'gamma)F-19 allows minimum detection limits of (1.06 +/- 0.12) and ( 1.85 +/- 0.2) at.ppm for the 110 and 197 keV gamma-rays, respectively. (C) 2000 Elsevier Science B.V. All rights reserved.