Scintillating properties of frozen new liquid scintillators1This work is part of the CERN Research and Development programme RD46.1

The light emission from scintillators which are liquid at room temperature was studied in the interval between +/- 20 degrees C and - 120 degrees C where the phase transition from liquid to solid takes place. The light yield measured at - 120 degrees C is about twice as much as that observed at + 20 degrees C. By cooling the scintillator from + 20 degrees C to - 120 degrees C and then heating it from - 120 degrees C to + 20 degrees C, the light yield varies in steps at well defined temperatures, which are different for the cooling and heating processes. These hysteresis phenomena appear to be related to the solvent rather than to the dopant. The decay time of scintillation light was measured at + 20 degrees C and - 120 degrees C. Whilst at room temperature most of the light is emitted with a decay time of 6-8 ns, at - 120 degrees C a slower component, with a decay time of 25-35 ns, becomes important. (C) 1999 Published by Elsevier Science B.V. All rights reserved.