Optimum lithium loading of a liquid scintillator for neutron and neutrino detection
Hans P. Mumm, Denis E. Bergeron, Mark A. Tyra, Jerome J. LaRosa, Svetlana Nour, T.J. Langford, Dimitry A. Pushin
Neutral particle detection in high-background environments is greatly aided by the ability to easily load 6Li into liquid scintillators. We describe a readily available and inexpensive liquid scintillation cocktail stably loaded with up to 1 % Li by mass. Compositions that give thermodynamically stable microemulsions (reverse-micellar systems) were explored, using a Comp-ton spectrum quenching technique to distinguish these from unstable emulsions. Scintillation light yield and transmittance were characterized. Pulse shape discrimination (PSD) was measured using a 252Cf source, showing that electronic-like and proton-like recoil events are well-resolved even for Li loading up to 1 %, providing a means of background suppression in neutron/neutrino detectors. While samples in this work were prepared with natLi (7.59 %6Li), the neutron capture peak was clearly visible in the PSD spectrum; this implies that while extremely high capture efficiency could be achieved with6Li-enriched material, a very inexpensive neutron-sensitive detector can be prepared with natLi.
Nuclear Instruments & Methods in Physics Research Section A-Accelerators Spectrometers Detectors and Associated Equipment