(n,nʹ[gamma]) reactions in 6̳3̳,̳6̳5̳Cu and background in 0[nu] [beta] [beta] experiments

Abstract

Measurements of (n, xnʹ[gamma]) reactions in Cu are important for understanding neutroninduced background for certain underground double beta decay experiments. Neutroninduced gammas are a contribution to background for the next generation of double beta decay experiments, which are designed to reach the sensitivity of the atmospheric neutrino mass scale (45 meV). Measuring and understanding the high-energy neutron excitations of shielding materials such as natCu are crucial for establishing shielding requirements and understanding background. In particular, the regions around the Q-values of candidate 0[nu beta beta] decay isotopes must be investigated. Partial [gamma]-ray cross sections for a natural copper target were measured using the GEANIE spectrometer in a broad-spectrum neutron beam at LANSCE. The experimental apparatus, and sources of systematic and statistical error are discussed. The results provide useful data for benchmarking Monte Carlo simulation of background events in future experiments. Furthermore, measuring specific (n, nʹ) excited state transitions in this material represents a nuclear structure contribution.