CASSPERR: A γ-γ cascade detector for resonant nuclear reaction analysis

Resonant nuclear reaction analysis (RNRA) is sometimes the only technique able to quantify elements in a matrix containing other elements. Background due to cosmic rays and natural radioactivity has limited traditional RNRA to samples with relatively high concentrations of the measured element, or to facilities with large amounts of passive shielding. Many nuclear reactions of interest in RNRA produce excited states in the resulting nuclei that then de-excite by product-specific sequences of photon emissions. The CAScade SPEctrometer for Resonant Reactions (CASSPERR) selects only events that match the desired combination of photon emissions. Rejection of other events greatly reduces the background, thus improving the signal to noise ratio (SNR). Since it is constructed from available commercial components, CASSPERR opens RNRA to typical ion beam analysis facilities. The design, operation and evaluation of CASSPERR with applications to materials science are currently under investigation.