PiC-code KARAT simulation of coherent Cherenkov radiation from a bunch passing through a hollow conical target

Abstract

In the report we present simulation results for angular distributions of the radiation as well as spectral distributions obtained by the PiC code KARAT for the conditions of the experiment [1]. We show that for strict satisfaction of the condition θcone=θCR/2 (θcone is an opening cone angle, θCR=arcos 1/βn) is the Cherenkov angle, β =v/c, n is a refractive index) a propagating radiation beam is retained a hollow structure for distances much larger than a radiator length. We simulated “radii” of such a structure at different distances from an exit radiator surface and estimated a divergence of the Cherenkov radiation (CR) beam.