Performance of a liquid scintillator at high count-rates for fusion applications

Energy resolution, peak position and n/γ discrimination have been measured for a liquid scintillator (Bicron BC 501 3.75 cm diameter x2.5 cm) as a function of count-rate for two different neutron energies, 2.4 and 14.1 MeV. Energy resolutions (FWHM) equal to 150 keV (at 2.4 MeV) and 610 keV (at 14.1 MeV) were achieved at low count-rates, i.e. ≤5x104 c/s. Modified standard electronics were used at count-rates ≥105 c/s and yielded resolutions approximately equal to 250 and 700 keV respectively. At count-rates ≤2.0x105 c/s n/γ discrimination better than 99% was observed. Detector systems with such properties will be able to resolve center-of-mass neutron energy line broadening from thermonuclear plasmas with ion temperatures Ti > or approx. 4 keV (D-D) and > or approx. 10 keV (D-T). (orig.)