Monte Carlo simulations of thin internal targets in intermediate energy proton storage rings

Abstract

The feasibility of using thin internal targets in a recirculator mode without beam cooling is studied in a Monte Carlo simulation. The limiting factor is the growth of beam emittance and energy spread by small angle Coulomb scattering and energy loss straggling. The corresponding probability density distributions are derived for proton energies ≳ 1 GeV and target thicknesses ≲ 10 −6 radiation length. It is very important to take the low intensity single scattering tails of those distributions into account as the beam distortions result from on the order of 10 6 passes through the target. The beam emittance, energy spread and survival probability are calculated as a function of turn number. Numerical results are obtained for a typical case (1.5 GeV kinetic energy protons incident on a 10 μg/cm 2 thick carbon target) using the design parameters of the cooler synchrotron COSY. The calculations are compared with simple analytical estimates. They demonstrate that thin self-supporting internal targets can be used for experiments in storage rings above 1 GeV.