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F. Schwellnus 1 , T. Gottwald 1 , C. Mattolat 1 , V. Sonnenschein 1 , K. Wendt 1 ,

Proposal to the INTC, 21. May 2007. Off-line Tests and first On-Line Installation of the Laser Ion Source Trap LIST - Application for Test of CVC and CKM Unitarity. F. Schwellnus 1 , T. Gottwald 1 , C. Mattolat 1 , V. Sonnenschein 1 , K. Wendt 1 ,

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F. Schwellnus 1 , T. Gottwald 1 , C. Mattolat 1 , V. Sonnenschein 1 , K. Wendt 1 ,

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  1. Proposal to the INTC, 21. May 2007 Off-line Tests and first On-Line Installation of the Laser Ion Source Trap LIST- Application for Test of CVC and CKM Unitarity F. Schwellnus1, T. Gottwald1, C. Mattolat1, V. Sonnenschein1, K. Wendt1, R. Catherall2, B. Marsh2, F. Österdahl3, V. Fedosseev2, K. Blaum1,4, H.-J. Kluge4, S. Schwarz5 • 1 Institut für Physik, Johannes Gutenberg Universität Mainz • 2 CERN Physics Department • 3 Department of Physics, Royal Institute of Technology, Stockholm • 4 Gesellschaft für Schwerionenforschung, Darmstadt • 5 NSCL, Michigan State University, East Lansing

  2. Overview • The idea: Development of an ion source which combines very high selectivity with excellent control over the ion beam properties. • The basis: The successfull joint material and laser tests for RILIS at the off-line separator in Jan. 2007 • The method: Combination of the advantages of a laser ion source with those of a radio frequency quadrupole cooler and buncher. • The physics case: Test of CKM unitarity and constant vector current hypothesis CVC by mass measurements on 62Ga and 62Zn using ISOLTRAP • The proposal: Request for off-line and on-line beam time on 62Ga & 62Zn at ISOLDE in 2008 INTC Meeting 21.05. – 22.05.2007

  3. Ion Repeller Ti:Sa 1 Gas filled RFQ Trap Ti:Sa 2 Ti:Sa 3 Nd:YAG 2. Gas filled RFQ Trap Section for Bunching and Cooling Motivation for RILIS & LIST Production of isobarically pure ion beams with optimum spatial and temporal ion pulse control using a gas-filled RFQ structure Mass Separator ISOLDE RILIS Source Laser- Beams Ion Beam Proton Beam HV Platform to Experiments Laser System • Atomic Beam Source • 3. Mass Separator with Surface Ion Reppeler 4. Laser System INTC Meeting 21.05. – 22.05.2007

  4. Principle of the LIST INTC Meeting 21.05. – 22.05.2007

  5. Technical Realization LIST prototypes developed and characterized in off line tests @ Mainz RISIKO MS LIST 1 LIST 2 LIST 3 (in preparation) Efficient resonance ionization via an all-solid state Ti:sapphire laser system: INTC Meeting 21.05. – 22.05.2007

  6. 60 kV RISIKO Mass Separator @ UMz ISOLDE 2 Frontend UMz Ti:Sa laser system Orsay Emittance Meter 60 kV RISIKO Mass Separator @ IPhy, UMz INTC Meeting 21.05. – 22.05.2007

  7. Mainz Ti:Sapphire Laser Setup Pump laser: Photonics Industries Nd:YAG, 532 nm, >80 W at 10 kHz Tunable lasers: 2 single & 1 double sided UMz Ti:Sapphire lasers - frequency doubling, tripling and quadrupling - computerized temporal and spectral control - efficient ionization of 19 elements demonstrated tested or in user at:IKch&IPhy@UMz, TRIUMF, JYFL, Oak Ridge, LLN, ISOLDE, UNagoya commercialized at the International Laser Fair, Munich, June 2007 INTC Meeting 21.05. – 22.05.2007

  8. Characterization of Prototype Performance Tests of different modes of operation: • Ion guide, without bunching • Bunching, low intensity, sharp beam energy (< 1 eV) • Bunching, high intensity, broad beam energy (> 1 eV) Important parameters for characterization: • Overall ionization efficiency • Isobaric selectivity via surface ion suppression • Spatial emittance • Energy distribution • Temporal structure of ion bunches LIST 2 Prototype dimensions: Length: 10 cm Diameter: 6 cm Field Radius: 0.5 cm fitting into ISOLDE target INTC Meeting 21.05. – 22.05.2007

  9. LIST Efficiency in the Ion Guide Mode • Efficiency curve Temporal profile on peak • LIST operation as ion guide without buffer gas or trapping, • surface ion repeller voltage optimized for selectivity INTC Meeting 21.05. – 22.05.2007

  10. Optimization of Efficiency with LIST 2 Incomplete suppression of background from too high atomic vapor density in trap: - collisional ionization - electron bombardment ionization - field and black body ionization INTC Meeting 21.05. – 22.05.2007

  11. Specifications of LIST 2 derived from RILIS and LIST Measurements in Ga @ RISIKO, UMz LIST RILIS@UMz Efficiency 2 cm atomizer 5,1·10-5 1,5·10-2 Suppression of surface ions (K/Ga) 2 cm oven length > 1000 - > 106 ions / shot - Trap capacity ~1.0  mm mrad ~1.5  mm mrad Emittance ~ 5 ms > 50 ms 4 cm oven length Time structure • Efficiency is fully determined by atomic beam collimation and atomizer length INTC Meeting 21.05. – 22.05.2007

  12. LIST Geometry and Ionization Efficiency repeller electrodes extraction- lenses extraction electrode segmented, linear quadrupole (filled with He - buffergas) lasers atomic beam source ionization region extraction region • High Efficiency via well collimated atomic beam & low ionization rate before trap volume • Optimum value so far: LIST ~1% of RILIS efficiency  further improvements of atomic beam source in progress INTC Meeting 21.05. – 22.05.2007

  13. Emittance Measurements Laser vs. Surface Ions Results from Orsay emittance meter @RISIKO, UMz, April 2007, LIST in ion guide mode Simulations for bunching using Simion 3D & LISBUN rms  1,3  mm·mrad rms  1,0  mm·mrad INTC Meeting 21.05. – 22.05.2007

  14. ISOLDE 2 front end preparation for LIST target INTC Meeting 21.05. – 22.05.2007

  15. Placement of the LIST within the ISOLDE target unit INTC Meeting 21.05. – 22.05.2007

  16. LIST Status and ISOLDE Beam Requests OFF-line tests: UMz Ti:Sa laser system operation at off-line Separator in Jan./Feb. 2008 First characterization of ISOLDE LIST target on Ga, Ca, Ni and Mn Request for 4 weeks of off-line separator use during winter shut down in close exchange and collaboration with ISOLDE ion source crew On-line investigations: On-line installation & use of first ISOLDE LIST ion source on ZrO2 target 15 shifts in spring/summer 2008 for LIST characterization and 62Ga 12 shifts on autumn 2008 for LIST refinement and 62Zn using LIST/ZrO2 target/ion source combination with laser ionization INTC Meeting 21.05. – 22.05.2007

  17. Maximum Ion Storage Capacity • High importance parameter in case of high production rate of neighboring isotopes • Integral ion beam 0,2 nA, Trap rate 350 Hz, 5 Lasershots on, 15 off, p = 3.8·10-4 mbar • Maximum loading capacity: 4·106 Ions / cooling cycle •  Loss of reasonable ion pulse time profile ~ 2 µs ~10 µs Maximum loading capability Few ions in LIST trap INTC Meeting 21.05. – 22.05.2007

  18. Time Structure INTC Meeting 21.05. – 22.05.2007

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