1. Holger Kollmus - VBE-UHV 1 SIS100_1 ERDA Measurements ERDA – Measurements: Understanding of Ion Beam-Loss Induced Desorption

2. Holger Kollmus - VBE-UHV 2 Objectives elemet specific depth profiling of samples by detection of elastically scattered recoil ions surface - bulk information characterization of sample properties and possible modification under ion irradiation time resolved monitoring of sample evolution in situ cleaning of target using Xe-sputter gun access to physics of ion induced desorption higher intensity  more beam loss more beam loss  higher pressure higher pressure  shorter beam life time FAIR: SIS18  10 12 U 28+ / s @ 4Hz Peter Spiller, December 2001, 8.75 MeV/u U 28+ Desorption Yield Measurements of well characterized Materials using ERDA and RBS Dynamic Vacuum and Beam Life Time Ion Induced Desorption Decreases the Beam Life time

3. Holger Kollmus - VBE-UHV 3 Status of ERDA-Experiment 12-2006 beam times Jun/2005 Ca: commissioning, desorption of silicon, influence of surface contaminations Jul/2005 Xe: influence of oxide layer on stainless steel Jan/2006 Xe: desorption of high purity copper, influence of oxide layer, desorption of gold terminated copper, secondary electron emission Feb/2006 Xe: comparison of different coating techniques Nov/2006 C: long term stability of gold coatings on copper using RBS, NEG characterization Dez/2006 Xe: desorption yield measurement and characterization of TSC test of special bake out procedure, desorption of hot targets Ni Fe Cr Si O N C

4. Holger Kollmus - VBE-UHV 4 ERDA Time Schedule Jan 2006 Nr.Task123412341234 1ERDA Measurements 2Set-up of UHV-ERDA at the HLI, Commissioning 3Measurements with stainless steel targets and silicon. Influence of oxide layer? 4 Measurements with Copper and Gold coated Copper 5Desorption yield contribution of secondary electrons 6 Desorption yield of pump. and satur. surfaces 7Exp. with layered targets, diff. barriers 8Desc. on adequate chamber and or collimator material 2005 2006 2007 Dez. 2006: All tasks finished

5. Holger Kollmus - VBE-UHV 5 Influence of Oxide Layer on Copper (I)  =360  =1500 Influence of secondary electrons and ions tested in parallel

6. Holger Kollmus - VBE-UHV 6 Influence of Oxide Layer on Copper (II) higher desorption yield from copper oxide surfaces compared to raw copper results can be qualitatively explained within the Thermal Spike and the Coulomb Explosion Model Copper is a good candidate if we prevent oxidation  Gold coating of copper disadvantage: high Z material diffusion of gold and copper

7. Holger Kollmus - VBE-UHV 7 RBS Monitoring of Thin Film Gold Coating Evolution of a gold coating during bake-out monitored using RBS (Ruthford Back Scattering)

8. Holger Kollmus - VBE-UHV 8 ERDA Milestones today we can report on: Is the ion induced desorption a surface or bulk effect? Mainly surface, but the bulk can deliver hydrogen! What is the influence of surface contamination of silicon wafer to the desorption? The contaminations are sputtered and contribute to the pressure rise! Influence of oxide layer on stainless steel. Is the pressure rise due to the sputtered Oxide? No, but the oxide layer amplifies the pressure rise compared to pure metal! How does the treatment of copper influence the Desorption? Desorption can vary at least by a factor of 5 using the same sample with only different history! Desorption yield of saturated NEG? Pumping surfaces are desorbing more (NEG and Pd)! First RBS and ERDA investigations on thin film NEG coating. RBS investigations of layered targets (Au coatings, diffusion barriers) Contribution of secondary particles? Can be measured and identified, but plays only a minor role for perpendicular impact! soon we can report on:  Decision on an adequate material and material modification for low desorbing collimators for the SIS18 (2007) next step:  Low Z copper terminations without diffusion. Implementation to the SIS18  We are in the time schedule and we have even more results and applications than expected, e.g., RBS of thin film NEG coating (quality control).

9. Holger Kollmus - VBE-UHV 9 Publications UHV-ERDA Investigations on Ion-Induced Desorption H. Kollmus, M. Bender, W. Assmann, R. Dörner GSI Scientific REPORT 2005 (2006) UHV-ERDA Investigations on Ion-Induced Desorption H. Kollmus, M. Bender, W. Assmann, R. Dörner Jahresbericht Beschleunigerlabor, LMU München 2005 (2006) Understanding of Ion-Induced Desorption using the ERDA Technique M. Bender, H. Kollmus, W. Assmann European Particle Accelerator Conference 2006, Proceedings, TUPCH174 (2006) Desorption Yields of Differently Treated Copper Samples Characterized With ERDA M. Bender, H. Kollmus, W. Assmann submitted to NIM B (accepted!) Ion-Induced Desorption Yield Measurements of bare and coated Stainless Steel, Nb, Mo, Ta, W, and Re Samples irradiated with 1.4 MeV/u Zn 10+ ions at GSI H. Kollmus, M. Bender, A. Krämer, and E. Mahner to be submitted in Dez. 2006 to PRL-ST-AB

10. Holger Kollmus - VBE-UHV 10 ENDE

11. Holger Kollmus - VBE-UHV 11 Status of ERDA-Experiment 01-2006 (a) Residual Gas Analyser Detector Xe Sputter Gun Beam  Target Holder Feedthrough Faraday Cup static vacuum 10 -11 mbar, only UHV-ERDA worldwide