Beam loss distribution calculation and collimation efficiency simulation of a cooler storage ring in a heavy ion research facility

University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China(Received 18 November 2013; published 28 August 2014)The Heavy Ion Research Facility in Lanzhou is an ion cooler storage ringfacility in China’s Institute ofModern Physics. The beams are accumulated, electron cooled, accelerated, and extracted from the maincooler storage ring(CSRm) to the experimental ring or different terminals. The heavy ion beams are easilylost at the vacuum chamber along the CSRm when it is used to accumulate intermediate charge stateparticles.Thevacuumpressure bumpduetotheion-induceddesorptioninturnleadstoanincreaseinbeamloss rate. Inorderto avoidthe completebeam loss, the collimationsystem isinvestigated and planned tobeinstalled in the CSRm. First, the beam loss distribution is simulated considering the particle chargeexchanged process. Then the collimationefficiency of the lost particles is calculated and optimized underdifferent position and geometry of the collimatorsand beam emittanceand so on. Furthermore, the beamorbit distortion that is caused by different types of errors in the ring will affect the collimationefficiency.Thelinearizedandinhomogeneousequationsofparticlemotionwiththeseerrorsarederivedandsolvedbyan extended transfer matrix method. Actual magnet alignment errors are adopted to investigate thecollimation efficiency of the lost particles in the CSRm. Estimation of the beam loss positions andoptimization of the collimationsystem is completed by a newly developed simulation program.