Temperature Dependences and Gamma Radiation Stability of Liquid Scintillation Cocktails for n–γ Discrimination

To correctly use different devices, including liquid scintillators, operating parameters have to be known and be at disposal. Among many others, the temperature influence and radiation hardness play an important role. The liquid organic scintillators, namely, EJ-301 and EJ-309 (both Eljen Technology), and new custom-made cocktails based on 1-phenyl-3-(2,4,6-trimethylphenyl)-2-pyrazoline (PYR) and 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene (THIO) fluors have been tested for temperature stability and radiation resistance. The temperature dependence, in terms of neutron–gamma discrimination, was found to be very weak with the temperature coefficient in order of 10 ⁻⁴ MeVee/°C. As far as the gamma radiation resistance of scintillators goes, THIO proved to give consistent results almost independently of the absorbed dose. The EJ-301 exhibited the second-best result. EJ-309 was mostly comparable with PYR except for isomerization, which was observed at an absorbed dose from gamma irradiation greater than 10 kGy. In addition, the color change of borosilicate glass, serving as the casing, was noticed causing a decrease in light yield (LY).