First time measurement of gamma‐ray excited LaBr 3 :5% Ce 3+ and LaCl 3 :10% Ce 3+ temperature dependent properties

We have measured for the first time the temperature dependence of LaBr 3 :5% Ce 3+ and LaCl 3 :10% Ce 3+ gamma‐ray excited light yields and decay curves between 100 and 600 K. Under gamma‐ray excitation, both scintillators present a very good thermal stability over the entire temperature range. The light yield of LaBr 3 is maximum at 100 K and decreases monotonously from 100 to 600 K. The decrease at 600 K does not exceed 15% of the maximum value. The light yield of LaCl 3 is maximum at 600 K and decreases with decreasing temperatures. The lowest value is reached at 150 K and corresponds to 90% of the maximum light yield recorded at 600 K. Our results show that LaBr 3 :5% Ce 3+ and LaCl 3 :10% Ce 3+ crystals can be used in applications where temperature conditions are extreme such as in oil well logging. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)