Proton-induced X-ray emission analysis of thick and thin targets

The problem of preparing materials of biological origin for trace element analysis using PIXE (proton-induced X-ray emission) is examined. A distinction is made between targets in which beam energy loss and X-ray absorption are negligible (thin) and those in which they are not (thick). The computer code FUDGE which calculates X-ray absorption factors for thick targets is described and the results of calculations for several organic materials are presented. The results of analyses of both thick and thin targets of NBS SRM 1577 (bovine liver) are reported, and their accuracy, precision and detection limits are compared. (Auth.)