Crystals for high-energy calorimetry in extreme environments

Crystals are used as a homogeneous calorimetric medium in many high-energy physics experiments. For some experiments, performance has to be ensured in very difficult operating conditions, like a high radiation environment, very large particle fluxes, high collision rates, placing constraints on response and readout time. An overview is presented of recent achievements in the field, with particular attention given to the performance of Lead Tungstate (PWO) crystals exposed to high particle fluxes.