Pulse shape discrimination of ³He proportional counters via rise time discrimination at CASPAR

Nuclear astrophysics experiments have the need to measure reactions at low energies in order to understand the reaction rates at stellar temperatures. The low yields at these energies have prompted the need for underground experiments to reduce the environmental background. Despite this reduction, experiments can still be limited by the intrinsic background of a detector. To address this problem, we have implemented pulse shape discrimination utilizing the rise time of the signal for the CASPAR neutron detector system. CASPAR is located at the 4850’ level of the Sanford Underground Research Facility (SURF) located in Western South Dakota and is the first deep underground accelerator facility in the United States. This pulse shape discrimination technique will be presented, along with some initial results of its application to recent low energy measurements of ¹¹B(α,n)¹⁴N.