A High Z Scintillator

Abstract

Thallium Chloride, activated with iodides, has been found to scintillate. Photopeaks for the Cs137 .662 Mev gamma energy have been obtained with several crystals, while many other TICI crystals, prepared with different iodides of varying low concentration show smaller scintillation response. Pulse height varies with the activators used. The consistently largest output to date is measured for TICI(Be,I). A maximum pulse height of 2.5% relative to Nal(TI) has been measured. The best resolution value is 42% at .662 Mev for Cs137. The gamma ray excited luminescence agrees remarkably well with the low temperature Intrinsic luminescence of TICI at 4650 Å. A scintillation decay time of 0.2 microseconds is obtained. Having good mechanical and thermal shock resistance, high density and the highest atomic number of any scintillator known to date, Iodide activated TICI promises to be an Important new scintillator. The scintillation efficiency and decay time are sufficient for consideration in high energy counters and spectrometers.