Demonstration of fast multiplicity counting of 252Cf using plastic scintillators and silicon photomultipliers

We present a first prototype for a multiplicity counter of fast neutrons and γ rays, based on plastic scintillators coupled to silicon photomultiplier arrays, where the SiPMs are read out individually by the TOFPET2 ASIC providing time-stamps and charge information. We demonstrate the capabilities of our counter by measuring the Singles-, Doubles- and Triples-event rates of neutrons and γ rays (without pulse shape discrimination), for a 252Cf source with a nominal activity of 4.9 μCi, and comparing them with a GEANT4 simulation of the process.