Digital Pulse Shape Discrimination with the XIA Pixie-500 and EJ309

2013 J. D. Williams Student Paper 1st PlacePoster <br>Due to the shortage of Helium-3, research has been directed toward the development of alternative technologies capable ofreliable and efficient neutron detection. Liquid organic scintillatorsare being investigated as a possible replacement because oftheir ability to both detect fast neutrons and reject gamma raysin a mixed field of radiation through the use of pulse shape discrimination.Previous research by other investigators has pairedCAEN and Struck waveform digitizers with a variety of liquidorganic scintillators to perform digital pulse shape discriminationand time-of-flight experiments. We used the recently developed,12-bit, 500 mega-sample-per-second (MS/s) XIA Pixie-500 with2 EJ309 liquid organic scintillators to perform bench-top 252Cftime-of-flight experiments and investigate alternative methodsof digital pulse shape discrimination. The results of the timeof-flight experiment are presented. The three digital pulse shapediscrimination methods that were applied include the standardcharge integration technique and two alternative methods (basedon pattern-recognition and curve fitting) previously investigatedby D. Takaku, T. Oishi, and M. Baba.7 We found the pattern-recognitionmethod achieved the best neutron-gamma discriminationusing a quantitative comparison of separation that estimatesthe neutron/gamma misclassification rate by fitting overlappingGaussian distributions to the pulse shape parameter distribution.Due to its relative simplicity, the pattern-recognition algorithmcould potentially be implemented on a field-programmable gatearray (FPGA) enabling real-time neutron-gamma discriminationwith low misclassification rates.