Nuclear gamma cherenkov radiation from charged projectiles as a coherent effect in nuclear media

Abstract

In this paper we use a Foldy-Lax approach for the refractive index n( ω) of photons inside a nuclear medium and experimental data on the spin-averaged Compton forward scattering amplitude for protons and deuterons in order to describe the nuclear γ-Cherenkov radiation. An extension of the Bethe-Bloch formula for the electromagnetic stopping power of the nuclear medium is derived via the plasmonic solutions of the equation n 2( ω) = 0. Our special interest concerns the possibility of γ-Cherenkov radiation in relativistic heavy ion collisions expected if the projectile velocity exceeds the photon phase velocity in nuclear media. Our method predicts a γ-Cherenkov band between 140 and 315 MeV for normal heavy nuclei for projectile energies beginning with several tens gigaelectronvolts per nucleon. Numerical predictions for the γ-Cherenkov intensity as well as for the corresponding cross sections from nuclear collisions are presented. Signatures of the nuclear γ-Cherenkov radiation are discussed.