PNNL

Abstract

We have demonstrated the direct isotopic assay of alpha-emitters in liquids using passivated implanted planar silicon (PIPS) diodes coupled with selective chemical preconcentration. Direct alpha energy spectroscopy has been enabled by placing a chemically selective polymer film or sorbent layer that concentrate ions of interest into a thin layer upon the diode surface. With thin film-coated we were able to obtain in situ alpha spectra with energy resolution comparable to that of conventional alpha spectroscopy. Moreover, by utilizing sorbent coatings with high affinity for the actinides of interest, we have been able to selectively concentrate actinides of interest upon the diode surface resulting in a substantial increase in sensitivity relative to a direct measurement.