Low-energy photon spectrometry in nondestructive neutron activation analysis of environmental samples

Low-energy photon spectrometry (LEPS) with a Si(Li) detector is used for the nondestructive analysis of elements in complex environmental materials. Neutron irradiations were carried out with irradiation times from 2 to 5 hrs and a thermal neutron flux of about 8x1012ncm-2sec-1. Gamma-ray spectrometry was carried out by using a Ge(Li) detector. The LEPS assembly used in this work consists of a Si(Li) detector (80 mm2 and 3 mm depth, the thickness of the Be window is 0.025 mm), a detector bias (-1000 V), a preamplifier, a main amplifier and a 512-channel pulse-height analyser. Comparisons of gamma-ray spectrum and low-energy photon spectrum are given for air dust, kale powder, and W-1 granite. Low-energy photon spectra of animal muscles, NBS liver standard and lake sediment are shown for three different cooling times. Results on nondestructive neutron activation analysis of zinc in standard rocks by LEPS are also given. (T.G.)