Experimental evidence of strong electromagnetic shower enhancement induced by high-energy photons in a thick oriented tungsten crystal

Abstract

We have observed a significant enhancement in the energy deposition and secondary particle generation by 25-100 GeV photons in a 1 cm thick tungsten crystal oriented along its 111 lattice axes. At 100 GeV, this enhancement, with respect to that observed without axial alignment, is more than twofold. This is ascribed to the acceleration of the electromagnetic shower development by the strong axial electric field. Previous studies of the enhancement of electromagnetic interactions by coherent effects in this energy range have generally made use of samples of thickness 1 mm or less. Our results, obtained with a 1 cm thick crystal, could be crucial in the development of high-performance photon absorbers, ultra-compact electromagnetic calorimeters and beam dumps for use at the energy and intensity frontiers.