Response of gadolinium doped liquid scintillator to charged particles: measurement based on intrinsic U / Th contamination

• Published in: Journal of instrumentation 2018-04, Vol.13 (4), p.P04001-P04001
• Main Authors: Du, Q., Lin, S.T., He, H.T., Liu, S.K., Tang, C.J., Wang, L., Wong, H.T., Xing, H.Y., Yue, Q., Zhu, J.J.
• Format: Article
• Language: English
• Subjects: Charged particles; Contamination; Gadolinium; Neutron counters; Particle decay; Particle physics; Scintillation counters; Stopping power; Thorium; Uranium
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/13/04/P04001

A measurement is reported for the response to charged particles of a liquid scintillator named EJ-335 doped with 0.5% gadolinium by weight. This liquid scintillator was used as the detection medium in a neutron detector. The measurement is based on the in-situ α-particles from the intrinsic Uranium and Thorium contamination in the scintillator. The β–α and the α–α cascade decays from the U/Th decay chains were used to select α-particles. The contamination levels of U/Th were consequently measured to be (5.54±0.15)×10−11 g/g, (1.45±0.01)×10−10 g/g and (1.07±0.01)×10−11 g/g for 232Th, 238U and 235U, respectively, assuming secular equilibrium. The stopping power of α-particles in the liquid scintillator was simulated by the TRIM software. Then the Birks constant, kB, of the scintillator for α-particles was determined to be (7.28±0.23) mg/(cm2ċMeV) by Birks' formulation. The response for protons is also presented assuming the kB constant is the same as for α-particles.