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REX-ISOLDE F. Wenander ATC meeting 23/1-2007

Emiliano Piselli (EP) new since 1/9 2006 50% REX operator. Didier Voulot (DV) (REX phys, contact). Fredrik Wenander (FW) (REX phys, contact). Richard Scrivens (RS). T eam REX. REX-ISOLDE F. Wenander ATC meeting 23/1-2007. REX intro and performance Technical aspects

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REX-ISOLDE F. Wenander ATC meeting 23/1-2007

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  1. Emiliano Piselli (EP) new since 1/9 2006 50% REX operator Didier Voulot (DV) (REX phys, contact) Fredrik Wenander (FW) (REX phys, contact) Richard Scrivens (RS) Team REX REX-ISOLDE F. Wenander ATC meeting 23/1-2007 • REX intro and performance • Technical aspects • Integration and maintenance • Operational issues • Future and Conclusion

  2. Layout * charge breeding * 1+ ions to n+ REXEBIS MASS SEPARATOR Optional stripper ISOLDE 7-GAP RESONATORS @ 101.28 MHz 9-GAP RESONATOR @ 202.56 MHz ISOLDE beam Primarytarget High energydriver beam protons IH RFQ Rebuncher 60 keV 0.3 MeV/u 3.0 MeV/u 2.2 MeV/u 1.2 MeV/u REXTRAP Experiments * longitudinal accumulation and bunching * transverse phase space cooling * 6 cavities * 100 and 200 MHz, ~100 kW * 300 keV/u to 3 MeV/u

  3. REX – a broad spectrum The machine covers pulsed high tension, LN2 and LHe cryogenics, superconducting elements, UHV (1E-11 mbar), a scalable heavy ion linac, ‘invisible’ radioactive beams, high current electron beam, multi-charge ion source, quickly pulsed machine (short-lived elements), electrostatic and magnetic transport, exotic beam diagnostics, etc etc One of its kind!

  4. Comparison with Linac3 Heavy ion linac; similar energy; same # cavities linac but REX: • Built as an experiment • Not ‘standarised’ solutions • Heterogeneous subsystems • More compact, less analysing equipment • Varying elements (ion A/q) and beam energies • different for each run • stable beam for calibration + radioactive isotopes • ~20 isotopes/year, short runs - 3 days to 2 weeks • Low intensity beams - <100 particles/s to 1 nA • Beam injected from another machine (ISOLDE) • No injection into another accelerator • lower energy and emittance constraints

  5. * So far 45 radioactive isotopes (19 elements) 13 and 9 new isotopes 2005 and 2006 * 9 out of 10 successful runs during both runs REXTRAP separation of 40K and 40 Ca REX performance * Recent two year’s outstanding results 1. Energies now from 300 keV/u to 3.15 MeV/u 2. Mass range exceed specifications A~200 now possible, spec A<50 3. Breeding efficiency fulfilling design specs 4. Molecular beams 5. Isobaric mass resolution 6. Development work

  6. Operation 2006 + Beam delivered to experiments in time for runs tougher mini-coordination + Low energy part has been ‘ticking like a clock’ - Late pre-startup for first run (mid June) even if target date 1/4 RF not ready due to: vacuum leak in a cavity DV away 2 weeks, FW tied up with low energy part REX low priority - Sudden electron cathode failure prevented one test run - Problems with RF amplifiers - Discrepancy ISOLDE target yield to exp beam intensity Non-working FCs; Running in problems with new control system; Mechanical problems with tuners; Water leaks at EBIS; Amplitude pickup for IH failed; Forced patch installation on computers during runs; Capacitor in 9-gap amplifier broken (due to long power cut); Beam diagnostic FEC unstable etc…

  7. Remaining serious technical problems * Fragile electron cathode in EBIS No real alternative available (IrCe also breaks) Operate restrictively (i.e. low current ~200 mA) * Power and duty cycle limitation of 200 MHz amplifier Manufacturer required to modify the unit * Scaling of Linac not always fully reproducible Continued and deepened study this year (linearity phase, amplitude, optics) * Problematic to inject into the experimental setup Complete realignment with Minimove Extra quadrupole doublet lens Add an ISOLDE-type beam scanner grid after bending magnet * Late startups – REX lowest on the food chain Avoid Witch (9 T unshielded magnet) runs before a REX run Stricter time limits to support groups

  8. Integration / Consolidation Started 1 Jan 2004 – run for 6 years What remains? • Alignment started end of 2006 • BDI migration to Linux in progress; application programmes missing no hardware consolidation done; under discussion what to change • CO transfer of REXEBIS control to Linux in progress remains to move REXTRAP and beam transfer line optics to Linux 50% of the job done • PO REXEBIS consolidation in progress (to be finished spring 2007) REXTRAP remains 66% of the job done • RF miscellaneous hardware work to do 50% of the job done • VAC overhaul of the PLC programming; control system and application programmes missing minor hardware changes to carry out 30% of the job done REX operation and consolidation within budget every year

  9. REX daily technical support Under responsibility of AB groups since 1 Jan 2004 (before PH) * Application programmes Inefficient(?) to re-specify existing application programmes 50% of EP is allocated for ISOLDE application programming * Group support BDI – hardware interventions started up since 1 year, knowledge transfer in progress CO – part transferred to Linux covered PO – fully autonomous since >2 years, planning, implementation, documentation, callout RF – self-governed together with DV, planning, REX low priority, callout VAC- limited service; mounting of vacuum parts mostly not covered Situation improved significantly since 2004; still much job covered by REX phys (DV+FW) * General technical support Daily repair / maintenance and shutdown work done be DV and FW Technicians from AB/RF, ATB/IF, ABP/HSL help out occasionally

  10. Piquet * <5 support group call-outs outside working hours 2006 (all for RF or TS) * 30-40 REX phys (DV+FW) call-outs outside working hours excluding late setups and changes most problems solved by REX operators mini-course for the users before each run * Increased need for piquet interventions when REX -> AB systems * Recall – REX has short runs

  11. Day 0 RS assists low energy EP under training whole machine Day 1 Day 2 Day 3 Beam setup tasks and time I ISOLDE setup - Separator setup + proton scan on target (4-8 h) (ISO operators) - Basic target test (2-3 h) (ISO target sec+FW) - Understand beam behaviour (0-2 h) (FW) REX setup - Stable beam from EBIS through linac (2-4 h) (DV) - Beam from ISOLDE separator (2-4 h) (FW) - Beam through trap (3-4 h) (FW) - Beam injection into EBIS and REX separator (4-6 h) (FW) Late work - Continued linac tuning with stable beam (2-4 h) (DV) Early start - Determination of A/q, breeding times etc (2 h) (FW) - Radioactive beam to users (3-6 h) (DV+FW) depending on beam intensity and exp setup - General checks and further optimization of beam steering to experimental setup (DV+FW)

  12. Beam setup tasks and time II In addition squeeze in (Day 0 to 2) Advanced yield tests if required and requested (2-6 h) (ISO target sec) RILIS laser tuning with ISOLDE (if applicable) (2-4 h) (Laser experts) During actual run Each change of isotope or energy (2-8 h) (DV+FW) Yield checks (ISO target sec+FW) Optimisation and verifications (DV+FW) General comments * REX startup time >24 h effective time * Quality assurance (beam efficiencies) * Overview and effectiveness necessary coordinate ISOLDE, target tests, lasers, REX low energy, REX high energy, exp beam calibration run the setup in parallel were possible make use of the machine; early morning to late night, lunch in shifts RS assists EP under training

  13. Operational issues + REX is easier to operate nowadaysunderstanding increased dramatically running well considering its complexity • - Changes during evenings and weekends (goodwill basis) • situation unclear / difficult to refuse requests / maximise physics output • - REX physicist (DV+FW+RS) used for standard / repeated operation • - Overtime issues • on call 10 weekends REX + 2 weekends Linac3 (FW) • on call 10 weekends REX (DV) => operator status • ! OP involvement just started 1/9-2006 (EP) • very good news • ! Aim to transfer daily REX operation to OP • liberate ‘senior’ physicist staff for suited tasks • ! Recommend involvement of a 2nd ISOLDE operator • >1 year training period; cover the whole chain

  14. So why is REX working? * In-house knowledge and overview a small complex ‘one-of-a-kind’ machine must / can be known by heart * Local actions short runs requires rapid interventions -> repair things ourselves * Beam responsible and not only machine responsible knowledge of whole chain (protons -> ISOLDE -> REX accelerator-> experiment) * Mini-schedule and tight coordination effective use of time and ISOLDE * Considerable operator presence in the hall during the runs * Built by PhD students and fellows (one still around) dedication, pride and a REX spirit in the team

  15. EBIS test stand Minimove and Visions Minimove * Improved exp setup * Better beam optics * DV digging in -> progressing well! Energy upgrades * Increase physics potential * Assure facility stays competitive BNL type EBIS * Handle heavy elements well * Higher capacity

  16. Summary Problems * REX a low priority machine – people have scattered responsibilities * Responsibilities not yet not fully transferred to the support groups * REX physicists (DV+FW) cover other’s work * Missing dedicated part technician (as Linac 2/3 superintendent) * Daily / standard operation not transferred to OP Ideas and solutions * Don’t split the machine into low energy and high energy part? * Coordination physicist (target - ISOLDE separator – REX) * Improved situation after LHC completion (but 3 MeV test stand and Linac4 coming up…) * High in-house competence for the REX operators * Involve another ISOLDE operator in the REX Physics community until now very happy with REX

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