BEAM LOSS IN HIRFL-CSR DUE TO COLLISIONS WITH RESIDUAL-GAS IN VACUUM

This paper discusses the collision of heavy ions with residual gas ato ms in the vacuum and the cross-sections of the collision processes. Th e method calculating beam transmission efficiency in vacuum is present ed taking HIRFL and CSR machine as examples. Based on rich experimenta l data, a series of empirical formulae of calculating the cross-sectio n of charge changing process is given. The transmission efficiency cur ves of different sections in HIRFL and CSR are also calculated, and th us the reasonable requirements for HIRFL and CSR vacuum systems are gi ven. The calculation method has been checked by the measurements of va cuum and beam loss in HIRFL.