THE USE OF THE REACTION BE-9(ALPHA,GAMMA-N)C-12 TO DETERMINE THE ENERGY SCALE AND THE EFFICIENCY AT LOW ENERGIES OF STELLAR COLLAPSE NEUTRINO DETECTORS

Experiments for the detection of gravitational stellar collapse nu-BARe events are most frequently based on the reaction: nu-BARe + p --> n + e+, followed by delayed neutron capture in hydrogen n + p --> gamma + d, E-gamma = 2.2 MeV. Data obtained by a low intensity Am/Be source (as n and gamma-ray emitter), in association with MACRO scintillation counters, are being used to determine the capability of detecting delayed neutron capture from cascade n, gamma-ray emissions. The Be-9(alpha, gamma-n)C-12 reaction is a valuable tool for setting the optimum "stellar gravitational collapse trigger" working conditions both for the detection of the primary nu-BARe events and for the detection of the delayed neutron captures. The use of the Am/Be source allowed several experimental checks of Monte Carlo calculated detection efficiencies.