Low-Afterglow, High-Refractive-Index Liquid Scintillators for Fast-Neutron Spectrometry and Imaging Applications

• Published in: IEEE transactions on nuclear science Vol. 56; no. 3; pp. 989 - 993
• Main Authors: Lauck, R., Brandis, M., Bromberger, B., Dangendorf, V., Goldberg, M.B., Mor, I., Tittelmeier, K., Vartsky, D.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Afterglow; Afterglows; Arrays; Dissolution; Dynamic range; Fiber lasers; high refractive index liquid; Imaging; light decay characteristic; liquid scintillator; Liquids; Neutrons; Nitrogen; Optical materials; Optical pulses; Refractive index; Scintillation; single photon counting; Solvents; Spectrometry; Spectroscopy
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2008.2009449

For ion and neutron spectrometry and imaging applications at a high intensity pulsed laser facility, fast liquid scintillators with very low afterglow are required. Furthermore, neutron imaging with fiber (or liquid-core) capillary arrays calls for scintillation materials with high refractive index. To this end, we have examined various combinations of established mixtures of fluors and solvents, that were enriched alternatively with nitrogen or oxygen. Dissolved molecular oxygen is known to be a highly effective quenching agent, that efficiently suppresses the population of the triplet states in the fluor, which are primarily responsible for the afterglow. For measuring the glow curves of scintillators, we have employed the time-correlated single photon counting (TCSPC) technique, characterized by high dynamic range of several orders of magnitude in light intensity. In this paper we outline the application for the fast scintillators, briefly present the scintillation mechanism in liquids, describe our specific TCSPC method and discuss the results.