A 3He neutron detector for the measurement of reactions

( α , n ) reactions are possible neutron sources for nucleosynthesis processes in stars. At the Nuclear Science Laboratory (NSL) of the University of Notre Dame a neutron detector based on 3He counters embedded in a polyethylene matrix was built to experimentally investigate this type of reactions. Monte Carlo simulations were used to guide the design of the detector used in the experiments. The efficiency of the final detector was experimentally determined and compared to simulations. The detector will be used in future measurements in a next-generation underground laboratory for nuclear astrophysics.