Slowing-down of relativistic heavy ions and its influence on angular distributions of Vavilov-Cherenkov radiation

We performed calculations of Vavilov-Cherenkov radiation (VChR) angular distributions from relativistic heavy ions (RHI) taking account of their slowing-down in a radiator. The results of calculations show that the slowing-down of RHI in radiator leads to specific broadening of VChR ring thus forming specific VChR angular distribution which is different compared to well-known Tamm-Frank distribution. The key parameters which change drastically the VChR angular distribution from RHI are: energy, charge and mass of an ion; emission wave length and corresponding refractive index; stopping power and radiator thickness. The theory developed has been applied to the analysis of the earlier experiments (1996-2001) devoted to studies of the VChR angular distribution from Au RHI beam with energies ∼0.9 GeV/u at SIS-18 heavy ion accelerator (GSI, Darmstadt, Germany).