Neutron Spectroscopy Without Time-of-Flight Measurement: A DSP-Based Deuterated Scintillator Array

Development and evaluation of a large-volume multi-element digital-signal-processing (DSP)-based deuterated (C₆D₆) liquid scintillator array for the study of reactions involving neutrons without the need for measurement of neutron time-of-flight (ToF) is described. In-beam testing was conducted at the University of Notre Dame (UND) 10 MV FN tandem Van de Graaff accelerator using a deuteron beam at E_d=16.0 MeV. The energy response and detector efficiency of 100 mm dia. ×; 150 mm long cylindrical deuterated liquid scintillator (Eljen 315) detectors was determined in the range E_n=4.8 to 8.7 MeV and E_n=6.8 to 21.2 MeV, respectively. In addition, we determined that optimized digital pulse-shape discrimination (DPSD) in liquid scintillator detectors using enhanced liquid (Eljen 315MOD) and other methods can yield improved recoil-particle tagging. As we demonstrate, this is particularly important in deuterated scintillators at neutron energies above 15 MeV. This is especially advantageous for study of nuclear reactions involving radioactive beams, since these often have large, positive reaction Q values.