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The prompt gamma neutron activation analysis facility at Murr
A facility has been developed at the University of Missouri Research Reactor so that the unique features of prompt gamma-ray neutron activation analysis can be used to measure trace and major elements in samples. This facility consists of a radial beamport, external sample position with shielding, and a multi-mode counting system. A single-crystal silicon neutron filter installed inside the beamport passes most of the thermal neutrons while reducing fast neutron and gamma radiation associated with the beam. Using thin gold foils, the beam was measured at the sample position to be 5 × 108n cm−2 s−1, with a cadmium ratio of 421. Background measurements of thermal and fast neutrons at the Ge(Li) detector yielded 1 and 2 n cm−2 s−1, respectively. The multimode counting system consists of a Ge(Li) detector surrounded by an annular NaI crystal both of which are controlled by a computer-based analyzer system. Prompt gamma-ray spectra were collected in the energy range from 0.05 to 11 MeV. To establish the performance capabilities of the facility, irradiations of pure element or simple compound standards were performed to identify the prompt gamma-ray energies from each element, their count rates, and their interferences. Preliminary results are presented demonstrating the application of this technique to the analysis of standard reference materials.