On the design and installation of a Compton-suppressed HPGe spectrometer at the Budapest neutron-induced prompt gamma spectroscopy (NIPS) facility

An important aspect of the ongoing upgrade at the Budapest PGAA-NIPS facility has been the design and installation of a second Compton-suppressed gamma spectrometer. The aim was to provide excellent spectroscopic conditions for future position sensitive and large sample prompt gamma activation analysis applications. The optimum geometry of the setup was determined by Monte Carlo calculations with the MCNP-CP code. The suppression factors for various layouts (co-axial, perpendicular), shapes (cylindrical, tapered), and thicknesses were compared at different gamma-ray energies. The optimum configuration, as a trade-off between performance and cost, was selected, purchased, and installed. Several characteristic features of a collimated, Compton-suppressed system could be revealed, which allowed us to achieve a better and cost-effective performance. The calculations were validated with a N-14(n,gamma)N-15 calibration source.