The neutron time-of-flight (nTOF) diagnostics used to characterize implosions at the National Ignition Facility (NIF) has necessitated the development of novel scintillators that exhibit a rapid temporal response and high light yield. One such material, a bibenzyl-stilbene mixed single-crystal organic scintillator grown in a 99.5:0.5 ratio in solution, has become the standard scintillator used in the nTOF diagnostic at NIF. The prompt fluorescence lifetime and relative light yield as a function of proton energy were determined to calibrate this material as a neutron detector. The temporal evolution of the intensity of the prompt fluorescent response was modeled using first-order reaction kinetics and the prompt fluorescence decay constant was determined to be 2.46 � 0.01 (fit) � 0.13 (systematic) ns. The relative response of the bibenzyl-stilbene mixed crystal generated by recoiling protons was measured, and results were analyzed using Birks relation to quantify the non-radiative quenching of excitation energy in the scintillator. The relative response data, while similar to previously reported values for a xylene-based liquid scintillator, differ in their overall energy dependence. The implications of this difference will be discussed, and plans for future highly-segmented nTOF systems will be presented.

Characterization of a stilbene-doped bibenzyl single-crystal organic scintillator for fast neutron spectrometry

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.