A prototype neutron-detector array for future deep-underground s-process studies

Abstract: We report a novel neutron-detection approach employing an EJ-309 liquid scintillator surrounded by six 3He proportional counters. Tests were performed at the FRANZ facility of the Goethe-University Frankfurt using the 7Li(p,n0)7Be reaction, producing neutrons across energies 50-720 keV. The scintillator's neutron energy quenching is determined, and its neutron/gamma-ray discrimination performance is evaluated. The lowest detectable neutron energy is 163 keV. EJ-309 - 3He counter neutron coincidences are compared with those from simulations. This array forms the prototype of a larger design, called scintillator-3He array for deep-underground experiments on the S-process, currently undergoing construction and testing for an upcoming deep-underground study of the 22Ne(alpha,n)25Mg reaction cross-section at the freshly-commissioned Bellotti Ion Beam facility of the INFN Laboratori Nazionali del Gran Sasso. This upcoming project is expected to achieve exceptionally low sensitivity for measuring the cross section at energies of interest for the astrophysical 'weak' and 'main' slow neutron-capture processes.