PHOTON-TAGGED NUCLEAR-REACTION ANALYSIS FOR TRACE-ELEMENT DETERMINATION

The new trace element measurement technique ''photon-tagged Nuclear Re action Analysis'' (pNRA) is introduced and the experimental procedures are described in detail. The pNRA-technique is an ion-beam analytical technique intended for the determination of the abundance of the ligh test elements, ranging from lithium to phosphorus. The technique is a complement to the PIXE technique. pNRA is a multiparameter technique, using fast coincidence criteria and high time resolution which identif ies and measures the products of nuclear reactions from which the amou nt of an element in the irradiated target can be determined. A detecti on system suitable for use in pNRA analysis is described. Different as pects of experimental parameters, e.g. time resolution and gamma-effic iency, are discussed and evaluated. Yield curves for all relevant ligh t isotopes are presented for a proton beam energy between 3.5 and 3.75 MeV, and minimum detection limits (MDLs) are extracted for different environments. The results of the MDL measurements with pNRA are compar ed with the detection limits of other frequently used techniques such as proton-induced gamma-emission (PIGE) and particle elastic scatterin g analysis (PESA), and are shown to match these other techniques very well. (C) 1997 Elsevier Science B.V.