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SIS100_1 ERDA Measurements

SIS100_1 ERDA Measurements. ERDA – Measurements: Understanding of Ion Beam-Loss Induced Desorption. Objectives. Dynamic Vacuum and Beam Life Time Ion Induced Desorption Decreases the Beam Life time. Desorption Yield Measurements of well characterized Materials using ERDA and RBS.

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SIS100_1 ERDA Measurements

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  1. SIS100_1 ERDA Measurements ERDA – Measurements: Understanding of Ion Beam-Loss Induced Desorption

  2. Objectives • Dynamic Vacuum and Beam Life Time • Ion Induced Desorption Decreases the Beam Life time Desorption Yield Measurements of well characterized Materials using ERDA and RBS 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 Peter Spiller, December 2001, 8.75 MeV/u U28+ FAIR: SIS18  1012 U28+ / s @ 4Hz

  3. Ni Fe Cr Si O N C 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

  4. ERDA Time Schedule Jan 2006 2005 2006 2007 • Dez. 2006: All tasks finished

  5. Influence of Oxide Layer on Copper (I) =360 =1500 • Influence of secondary electrons and ions tested in parallel

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

  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. 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. ENDE

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

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