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Results with ISCOOL a new Radio Frequency Quadrupole Cooler and Buncher at ISOLDE

Results with ISCOOL a new Radio Frequency Quadrupole Cooler and Buncher at ISOLDE. P. Delahaye, H. Fr å nberg, AB-OP-PSB, ISCOOL, COLLAPS, ISOLDE collaboration. Where at ISOLDE. ISCOOL. Installation in pictures. INSTALLATION. Implementation of the RFQ into the ISOLDE vacuum system.

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Results with ISCOOL a new Radio Frequency Quadrupole Cooler and Buncher at ISOLDE

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  1. Results with ISCOOL a new Radio Frequency Quadrupole Cooler and Buncher at ISOLDE P. Delahaye, H. Frånberg, AB-OP-PSB, ISCOOL, COLLAPS, ISOLDE collaboration ISOLDE WS 2007

  2. Where at ISOLDE ISCOOL ISOLDE WS 2007

  3. Installation in pictures ISOLDE WS 2007

  4. INSTALLATION • Implementation of the RFQ into the ISOLDE vacuum system. • Construction of HV platform and HV cage of the RFQ. • Standard controls in the working sets: QP arrays for the RFQ and for the beam tuning after the cooler. • RF and gas still on LabVIEW. ISOLDE WS 2007

  5. OPERATION OF ISCOOL • Set-up by the ISOLDE operators. • Improved transmission past the switchyard  Improved (faster and easier) set-up for the beam to the experiments ISOLDE WS 2007

  6. Principle • Three elements: • RF quadrupolar field • Radial confinement • DC potentials • Extracting ion in bunches or in continuous mode • Buffer gas •  Ion motion cooling ISOLDE WS 2007

  7. Transmissions • Potentials along the axis 5-2V/cm 50V (30V enough) 80eV TRAPPING INJECTION ~1E-2 mbar 4He 10-2mbar l/s EXTRACTION Transmission dependence on the emittance of the ISOLDE ion sources. ISOLDE on-line surface ion sources has smaller emittance than ISOLDE FEBIAD ion sources (<25 π·mm mrad). The off-line tests were performed with an ion source with ε = 35π mm mrad ISOLDE WS 2007

  8. Bunching mode 50V (30V enough) 5-2V/cm 80eV 30-60 keV TRAPPING ~1E-2 mbar 4He 10-2mbar l/s INJECTION EXTRACTION ISOLDE WS 2007

  9. Cooling time • TOF < 1ms from the entrance to the exit of the RFQ • No losses for short lived ions. • 1 passage is enough to get a cold beam • as measured off-line, and other labs as predicted by simulations for other systems ISOLDE WS 2007

  10. Emittance measurements (off-line) • 10 x decrease of the beam emittance • The worst case scenario at ISOLDE is the FEBIAD ion source with >25 p·mm·mrad emmittance. • Injection efficiency into the cooler is depending on the beam emittance from the ISOLDE target and ion source unit. ~35p·mm·mrad 95% emittance ~2.2p·mm·mrad 95% emittance ISOLDE WS 2007

  11. Space charge limits • Up to 108/s!! As measured with FC (data under analysis with MCP) 23Na 85Rb 39K, Collection time=10 ms–1 sec Extraction time 150 us ISOLDE WS 2007

  12. Bunch width Depends on the space charge and cooling time Collection time=cooling time ISOLDE WS 2007

  13. Yield measurements • 26Na T1/2=1.07 s • 48K T1/2=6.8 s • Yields in continuous mode: • 26Na :1.2e6 at/uC • 48K: 2.2e4 at/uC • Yields in bunched mode • analysis under progress ISOLDE WS 2007

  14. HOT SPOTS ISOLDE WS 2007

  15. Results • High transmission efficiencies • Easy beam tuning to experiments • Yield measurements continuous vs. bunched mode • Losses due to trapping time (analysis in progress • First measurements with radioactive isotopes performed together with COLLAPS (see next talk) ISOLDE WS 2007

  16. ISOLDE HRS + Cooled beams ISCOOL HRS ISOLDE WS 2007

  17. Outlook Up to October 2007: From Nov. 2007: Next step: Upgrade of HRS Mag 90: EURISOL HIE Isolde: ISOLDE WS 2007

  18. Thanks to: AB-OP-PSB-iso team: Pascal, Erwin, Magnus, Emiliano and Tim. AB/ATB AB/CO AB/PO AB/VAC SC/RP ISOLDE collaboration COLLAPS collaboration ISCOOL collaboration ISOLDE WS 2007

  19. ISOLDE WS 2007

  20. ISCOOL tests with COLLAPS 46K Beam 1E5 ions/s after the cooler. Collection time 20 minutes, with 300ms bunching and a 12us gate and 2mW of laser power. Bunched:12us gated spectra Singles (continuous counting) Background suppression factor~1E4 ISOLDE WS 2007

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