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

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

Motivation for RILIS & LIST Production of isobarically pure ion beams with optimum spatial and temporal ion pulse control using a gas-filled RFQ structure ISOLDE RILIS Source Mass Separator Ion Repeller Ti:Sa 1 Ti:Sa 2 Ti:Sa 3 Nd:YAG Laser- Gas filled RFQ Trap 2. Gas filled RFQ Trap Section for Bunching and Cooling 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

Principle of the LIST INTC Meeting 21.05. – 22.05.2007

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

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

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

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

Distance between source and trap 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 Distance between source and trap Efficiency 10 mm ~ 1·10-5  5 mm > 3,2·10-5 INTC Meeting 21.05. – 22.05.2007

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

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 Time structure 4 cm oven length Efficiency is fully determined by atomic beam collimation and atomizer length INTC Meeting 21.05. – 22.05.2007

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

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

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

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

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

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 Few ions in LIST trap Maximum loading capability INTC Meeting 21.05. – 22.05.2007

Time Structure INTC Meeting 21.05. – 22.05.2007