CSNSM/IAS/ISMO/IPNO joint seminar

Le séminaire comprend deux interventions complémentaires :

MATerials Research with GeV ions at GSI
Dr. Daniel Severin
GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany

GSI Materials Research operates several experimental stations for sample irradiation with high-energy heavy ions in the regime of 3 to 11 MeV per nucleon at the Linear Accelerator UNILAC and several hundred MeV per nucleon at the Heavy Ion Synchotron SIS18. The presentation will give an overview of the beamlines, including the heavy ion microprobe and the high energy SIS beamline. Particular focus will be brought to the in-situ and on-line analytical techniques available at the M-Branch.

Swift heavy ion induced desorption
Dr. Markus Bender
GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany

Ion induced desorption is a severe intensity limitation in modern high intensity heavy ion accelerators. During the past decade ion induced desorption has been intensively investigated with the aim of achieving stable vacuum conditions in the accelerator. The underlying mechanism could be revealed as thermal driven release of gas from the surface.
With upcoming next generation accelerator facilities such as FAIR or SPIRAL2, high intensive ion beams, up to 5e14 ions per second are impinging onto a production target. Even with low desorption yields, the resulting pressure rise (with partially activated gas) is hard to handle. Even worse, the target areas will be unbaked and so far a heating is not foreseen. Therefore we have tested several in situ cleaning procedures for the critical areas, including cleaning by the beam itself. Another challenge in new accelerators is desorption from cryogenic surfaces where the surface coverage and the thermodynamic properties are not well defined.
In the talk we will focus on actual results of desorption yield measurements from unbaked targets and give a preview of planned experiments on cryogenic surfaces.