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Summary Betriebsseminar Salzau May 5-8, 2003 F. Willeke, DESY

Summary Betriebsseminar Salzau May 5-8, 2003 F. Willeke, DESY. Short Review HERA Run 2002 / 2003 Luminosity Polarization Backgrounds Shutdown Activities Plans for Restart. Short Review of HERA Run 2002/2003. January-March 2002 Repairs, Collimator modifications, machine studies

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Summary Betriebsseminar Salzau May 5-8, 2003 F. Willeke, DESY

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  1. SummaryBetriebsseminar SalzauMay 5-8, 2003F. Willeke, DESY Short Review HERA Run 2002 / 2003 Luminosity Polarization Backgrounds Shutdown Activities Plans for Restart

  2. Short Review of HERA Run 2002/2003 January-March 2002 Repairs, Collimator modifications, machine studies March 2002 Start up, machine studies, bakeout April 2002: Set-up of luminiosity, synchrotron radiation studies June-Sept. 2002 Luminosity Run with low intensity (5d/w), machine studies, background studies (2d/w) Sept./Oct. 2002 High Luminosity Studies, polarization Studies Nov. 2002-Febr. 2003 Luminosity Runs wih moderate intensity February 2003 Machine Studies, high luminosity studies, polarization Tune-up

  3. Operations Luminosity operations in February 2003 Luminosity Efficiency in February 2003: 43%

  4. D. Pitzl’s Plott of CJC2 Chamber currents contributions from ep gas events relative to values obtained in September 2002 Global trend follows the vacuum pressure, there is stagnation since December 2002

  5. Accelerator Handling, Understanding, Modeling, Improvements Beam based alignment Orbit feedback Improved magnet cycling Online optics correction Improved background tuning algorithm On-line IR beam envelopes inside magnet aperture Working on proton emittance control Improved beam stability Improved beam handling More save operations Higher beam quality Larger luminosity

  6. Beam Based Alignment

  7. Improvement of accelerator lattice: on-line correction of beam envelope and phase beating

  8. Online display of beam envelopes inside relative to limiting magnet apertures

  9. Proton Logitudinal Stability Coupled Bunches 2p-Mode pattern Coupled Bunches 4p-Mode pattern Phase Ocsillation Monitor Average Phase and Bunchlength Finding: HERA p bunches lenghened by longitudinal bunch instability Cure: Bunch-to-bunch synchrotron frequency spread by RF amplitude modulation with frev

  10. High Luminosity 120 Bunches Ip < 70 mA Ie < 35 mA Lpeak<2.7 x 1031 cm-2s-1

  11. Polarization • 4 Measures • Enhanced spin matching • Enhanced harmonic bump scheme • Improved closed orbit control • Close to perfect optics • 4 Steps • Test Polarisation in 72o optics in old >IR in 2000 • Repeat this test successfully in Oct 2002 with flat rotaotrs in South and North • Turn all all three Rotators simultaneously and tune up polarization • Collide polarized beam in North and South IR with protons 4 challenges • HERA is operated now with three pairs of spin rotators. • The solenoid fields are not locally compensated and the beam design trajectories are not perfectly parallel to the solenoid axis. • The luminosity upgrade enhances the electromagnetic fields in collisions with the proton beam. • The natural vertical positron emittance for a well compensated and spin tuned orbit does not match the proton vertical beam size. In order to avoid poor lifetime and transverse tails of the protons, the vertical positron emittance must be enlarged without affecting the polarization. Polarization Tune-up February 03

  12. Shut Down Activities PS Installation of bipolare choppers for VO VG South & Nor repair some ground faults maintenance of dump switches Cooling Reduction of cooling water temperature GI/GJ NR, SR (partially done, under discussion) Improvement of QR cooling Improve water cooling of cavities Injection Improvement of fast e-injection kickers Superconducting Cavities Exchange RF Windows Repair of HV Isolation coupler shaft, p-HF New power tubes 208MHz Tuning of Feedbacksystems Troubleshooting Stoerlinien 52MHz e-HF Plunger exchange at several RF Stations Klystrons tuning Interlock New door contacts, new cabling Water interlock WR Surveystraight sections in North and South rotators East, North, South, arc NE Vacuum e-beam pipe in GA-Magnet SL/NL 30m gets a NEG pump SR absorbers for RF-Finger in straigths coating of Absorber 4 SR, NR 11m with Cu-Mo movable collimator collimator ati 66m SL/NL Modification of RF screens at Pumping ports Absorbers 1 &2 NR, SR 3.5m, 6m New RF screens at rotator beam pipes beam pipes which replace HERA-B beam pipes new shutters at Insulation vacuum s GG/G install VPS with cold bypas p-Vacuumleck SR 28m Cold Magnets p Reconnect busses at VPS Stecker erneuen Diagnostics new e BPM system (electronics) partial replacement of p bpm electronic replace all fans for tunnel electronics Installation of OTR Monitors WL18m Wire measurment system repair work on electrical safety in tunnel electronics

  13. NEG in –GA e-Chamber NEG Pump 7mm

  14. Increase conductance of he pumping port Remove every second cross piece of the rf shield

  15. Molybdenum coating of Absorber 4 100mm Mo, 10mm Cu Braising Today 4 Absorber inserts available now But this is the critical path

  16. Schedule Summer/Fall 2003 Start up with beams (3 days delay) July 14 Turn-on both Rings July 17-31 Vacuum Conditioning operation August 1 -August 31 12 GeV, frequent warm up GG/GO Polarization Studies September 1-14 High energy conditioning Set-up Luminosity Operation Sept 14-30 Luminosity Operation for all experiments October 1-Dec 15 Accelerator Studies Dec 15-22 Maintenance days August 5, Sept 2, Oct. 7, Nov 4, Dec 2

  17. Machine Studies File system test Commissioning of new e –BPMs ORM e-Ring o check new BPM Electronics ORM p-ring o check BPM, CX, CP, QQ Scan apertures e & p Set up injection with fast injection kickers (opikickers) Beam based Alignmend reference measurement Adjust e-dump kicker bump Set up collimators omn the ramp P-collimaor settings inclding WR33 Check on backscattering from SR/NR Opimize Orbits a VFPS Opimize Orbits at Lpo Proton Injection shape Oscilation Compensaion using new OTR Monitors Commission Finger Monitors Test Lumipilot Establisch optimum e Optik ( SM & 72 degr exact per fodo cell) Set up new e-Feedback Check on e Chromaicity

  18. Conditioning with Beam

  19. Maximum Peak Luminosity Ieb = 0.300mA (design) 0.600mA (2 x design) Ipb= 0.600 mA (Y2000 max) 1500 mA2 4000 mA2 Can’t get to maximum Luminosity with 180 bunches Peak Luminosity Prospects 2003 A likely scenario

  20. Luminosity Prospects 2003 Turn-on and Conditioning 6 weeks Polarization studies 4 weeks Maintenance 5 days => Remaining for Luminosity Operation 45 days Operational Efficiency 50% Peak Luminosity L=4.0 x 1031 cm-2 sec-1 Average Peak Luminosity L=3.5 x 1031 cm-2 sec-1 Average Luminosity L= 1.25 x 1031 cm-2 sec-1 Integrated Luminosity = 20 pb-1

  21. Conclusions • Backgrounds in Experiment widely, though not completely understood • Time was well used to polish up the accelerator, many improvements • High luminosity demonstrated • High polarazation with collisions demonstrated • Improvement programme under way • Plans for restart being finalized

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