A Collimation Scheme for Ions Changing Charge State in the Leir Ring

Avalanche-like pressure rise and an associated decrease of the beam life-time, caused by (i) beam loss due to charge exchange interactions with rest gas molecules, (ii) electron capture from the electron beam of the electron cooler and (iii) ion impact induced outgassing, is a potential limitation for heavy ion accelerators. The vacuum system of the LEIR ring has to be upgraded to reach the dynamical vacuum pressure in the low 10− 12 Torr range necessary to reach design performance. A collimation system to intercept lost ions by absorber blocks made of low beam-induced out-gassing material will be installed. This paper reviews the collimation scheme and simulations of beam loss patterns around the ring.