High current heavy ion beam investigations at GSI-UNILAC

Abstract

The GSI Universal Linear Accelerator UNILAC and the synchrotron SIS18 will serve as injector for the upcoming FAIR-facility. The UNILAC-High Current Injector will be improved and modernized until FAIR is commissioned and the Alvarez post stripper accelerator is replaced. The reference heavy ion for future FAIR-operation is uranium, with highest intensity requirements. To re-establish uranium beam operation and to improve high current beam operation, different subjects have been explored in dedicated machine investigation campaigns. After a beam line modification in 2017 the RFQ-performance had deteriorated significantly; new rods have been installed and the RF-working point has been redefined. Also the Superlens-performance had become unsatisfactory; improved with a modified RF-coupler. With a pulsed hydrogen gas stripper target the uranium beam stripping efficiency could be increased by 65%. Various work has already been carried out to establish this stripper device in routine operation. With medium heavy ion beams a very high beam brilliance at the end of transfer line to SIS18 was achieved. Results of the measurement campaigns and the UNILAC upgrade activities will be presented.

RF-Acceleration Studies for the HBS-Linac Applying Alternating Phase Focusing Concepts

“…The HBS project will benefit from research on the subject of compact, thermal-loaded cavities, whereas the IH cavities will be employed in a different accelerator: the new heavy ion GSI continuous wave linear accelerator Helmholtz Linear Accelerator (HELIAC) [7,8]. The HELIAC will meet the demand for continuous wave beams of the superheavy element synthesis and material research community, whereas the existing UNIversal Linear ACcelerator (UNILAC) will be upgraded for pulsed high peakcurrent applications for the Facility for Antiproton and Ion Research at Darmstadt (FAIR) [9].…”