1 / 33

RHIC polarized protons – The next decade – Wolfram Fischer

RHIC polarized protons – The next decade – Wolfram Fischer. 14 May 2010 RSC Meeting, Iowa State University. Content. Run-9 performance (short) Run-11 upgrade plans and projections (short) Longer-term upgrade plans Polarization Luminosity Energy. Run-9 polarized protons. 250 GeV

gaia
Download Presentation

RHIC polarized protons – The next decade – Wolfram Fischer

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RHIC polarized protons – The next decade – Wolfram Fischer 14 May 2010 RSC Meeting, Iowa State University

  2. Content • Run-9 performance (short) • Run-11 upgrade plans and projections (short) • Longer-term upgrade plans • Polarization • Luminosity • Energy 2

  3. Run-9 polarized protons • 250 GeV • First colliding beam operation at 250 GeV • Upgraded CNI polarimeter • Magnet re-alignment near snakes • LEBT/MEBT modification (25% smaller emittance in RHIC) • Improved nonlinear chromaticity correction • Test of 9 MHz acceleration rf system • Triplet 10 Hz cold mass measurements • 100 GeV • First test of AGS horizontal tune jump system • Test of new low level rf system • Tests of spin flipper • All RHIC service buildings with A/C • Operational use of 10- and 12-poles (Yellow beam lifetime) 3

  4. Luminosity and polarization goals Had previously a goal of 60 here.(May reach 60 with source upgrade and electron lenses).

  5. Run-9 250 GeV p-pRun Coordinator: M. Bai First collideroperation with polarizedprotons at 250 GeV P= 34%(H-jet online) 5

  6. Run-9 100 GeV p-pRun Coordinator: C. Montag • Little progresscompared to Run-6 / Run-8 • Lpeak higher by up to 40% (lower e and b*) • DOES NOT lead to increased Lavg P= 55%(H-jet online) 6

  7. RHIC calendar time in store goal expectation After improvements in Run-8, time in store fell back in Run-9.Should assume 55% on average for future runs. 7

  8. Main limits for p-p performance and possible solutions • AGS : proton bunches with high intensity, high polarization and low emittance polarized source upgrade (under way) AGS horizontal tune jump system (tested in Run-9 and Run-10) • RHIC: polarization transmission to 250 GeV acceleration near 2/3 resonance (tested in Run-10) • RHIC: intensity transmission to 250 GeV beam dump system modifications (thicker beam pipe in dump) Yellow ramp transmission (9 MHz rf system) • RHIC: peak luminosity and luminosity lifetime  reached lower b* limit at 100 GeV(not necessarily a problem at 250 GeV) electron lenses allow for larger beam-beam parameter 8

  9. Polarized source upgrade – A. Zelenski • 3-year capital project (started in FY 2009) • Goals:1. H-ion beam current increase to 10mA(order of magnitude)2. Polarization to 85-90%(5% increase) • Upgrade components:1. Atomic hydrogen injector (collaboration with BINP Novosibirsk)2. Superconducting solenoid3. Beam diagnostics and polarimetry 9

  10. RHIC OPPIS produces reliably 0.5-1.0mA polarized H- ion current. Polarization at 200 MeV: P = 80-85%. Beam intensity (ion/pulse) routine operation: Source - 1012 H-/pulse Linac - 5∙1011 AGS - 1.5-2.0 ∙ 1011 RHIC - 1.5∙1011 Optically Pumped Polarized H–source at RHIC – A. Zelenski • 29.2 GHz ECR source used for primary proton beam generation • source was originally developed for dc operation • 10x intensity increase was demonstrated in a pulsed operation by using a very • high-brightness Fast Atomic Beam Source instead of the ECR source

  11. OPPIS upgrade with Fast Atomic Beam Source – A. Zelenski He – ionizer cell serves as a proton source in the high magnetic field. H+ H+ H- H0 H0 The ECR primary proton source replacement with the very high-brightness Fast Atomic Beam Source. Atomic H injector development in collaboration with BINP, Novosibirsk. New superconducting solenoid (3.0 T long flattop).

  12. OPPIS upgrade with Fast Atomic Beam Source – A. Zelenski He – ionizer cell serves as a proton source in the high magnetic field. H+ H+ H- H0 H0 The source produces ~ 3 A ! (pulsed) proton current at 5.0 keV. ~ 10 mAH- current, P = 85-90%. ~ 300 mA (high-brightness) unpolarized H- ion current.

  13. Polarized protons from AGS Intensity dependent polarization in AGS in Run-6 and Run-9 • AGS horizontal tune jumpsystem: first test in 2009, • Tests in 2010: • Better understanding of emittance growth mechanism(b-beat) • up to 5% more polarization Working on orbit feed forward for better reproducibility. Courtesy H. Huang 13

  14. RHIC polarization transmission to 250 GeV At current working point limited tune space between2/3 (beam loss) and 7/10 (polarization loss) on ramp.Need to test acceleration closer to 2/3 in Run-10 with Au.(Near integer WP less promising at this point.) Courtesy M. Bai 14

  15. RHIC polarization transmission to 250 GeV Test with Au beam in Run-10 (M. Bai et al.) Successful acceleration with DQ = 0.005 DQ = 0.005 corresponds to >90% polarization transmission. Simulations started to compare DA of Au lattice 2010 with proton lattice for 2011 (Y. Luo, X. Gu). 15

  16. Beam dump • Problem: • Quenched Q4 after beam dump several times with high intensity beam close to 250 GeV beam energy(also with Au beam recently) • Simulations by K. Yip, with L. Ahrens: • Increase of kick strength by 20% (6th kicker module)should allow 20% increase in intensity • Replacement of dump beam pipeshould allow 100% increase in intensity • Summer 2010 shut-down: • Will install new beam pipe in dump (2x thicker) 16

  17. RHIC Yellow ramp transmission Ramp transmission [%] Ramp transmission [%] Sharp drop in Yellow ramp transmission for  1501011 p Better transmission for same intensity in fewer bunches suggest electron clouds as contributing mechanism (V. Schoefer, APEX09), can be mitigated with 9 MHz rf, and in-situ coating. 17

  18. Further upgrades for p-p performance • Orbit control • on ramp(global, ~1Hz) reduces number of lost ramp during development • at store slow(global, ~1h, 24 h vertical movement) tighter tolerances at 250 GeV (IP, collimators) • at store fast(global, 10 Hz, triplet vibrations) reduces parameter (e.g. tune) modulation • 9 MHz rf systemrequires upgrade of RMMPS flattop-to-ramp switches,and independent Blue and Yellow longitudinal dampers preserves longitudinal and transverse emittances better on ramp, mitigation of Yellow intensity ramp transmission limit • PolarimetryCNI polarimeter (rate dependence, setup time)additional polarimeter in IP10 with collision • b* reduction to 0.5 m (perhaps 0.35 m)requires improvements in lattice corrections 18

  19. Further upgrades for p-p performance • Spin flipperneed modifications to eliminate global effects (installed in Run-10) • Collimation efficiencystudied with simulation move of collimator to IR12 (G. Robert-Demolaize, A. Drees) – gain not very large, alternatively study additional masks in experimental IRs • Electron lenses increase of beam-beam parameter – now at limit (x=0.007/IP) • In-situ beam-pipe coating for lower SEY(R&D)A. Hershkovich working with company (SBIR)  high risk R&D, but would reduce all e-cloud phenomena • Maintain/improve reliabilityperiodic review and upgrades based on observed failurestatistics and expected end-of-life failures expect 55% of calendar time in store in future run (on average) • … • Cooling at store energy (CeC R&D – V. Litvinenko) 19

  20. Orbit control – global orbit feedback (~1 Hz) M. Minty et al., IPAC10 Global orbit feedback successfully demonstrates (at store and on ramp) Allows for faster ramp development, better ramp and storeorbit maintenance with diurnal orbit changes. 20

  21. 10 Hz global orbit feedback – R. Michnoff et al. Feedback OFF Feedback OFF Position in triplet [mm] Feedback ON IR6 and IR8 Blue Q1 and Q3 horizontal BPM measurements with 10 Hz feedback ON vs. OFF (31.2 GeV Gold) Expect improvements in luminosity lifetime.[Necessarily of near-integer working point.] March 24, 2010 21

  22. Spin flipper – M. Bai et al. • AC and DC dipoles worked as expected • Coherent oscillation of Blue beam was global and had effect on Yellow beam • Tested orbit effect in Run-10 (successful) 22

  23. Electron lenses in RHIC e-beam p-beam Additional head-on beam-beam collision with electron beam can partially compensate beam-beam effect from other proton beam. • 2 electron lenses are under construction • goal of 2x luminosity increase together with source upgrade • plan to start using in Run-13 23

  24. Electron lenses in RHIC 6D beam lifetime simulation of electron lens (Y. Luo, IPAC10) Beam lifetime simulations arechallenging – Require good modeland supercomputer Nb = 3x1011without and with e-lens Simulationsshow full benefit of e-lens for Nb > 2x1011(i.e. with source upgrade) 24

  25. R&D for in-situ coating of arc beam pipes • Electron clouds limit proton emittance at injection, ramp transmission (Yellow) • Warm parts are largely coated with NEG • Cold arcs are stainless steel, not coated •  Need in-situ coating for arcs A. Hershkovich et al.IPAC10 R&D for magnetron mole Test tube coated with Cu 25

  26. Energy increase by 30% (325 GeV) 30% increase in energy (to 325 GeV) appears possible • Arc dipoles have margin • Arc quadrupoles have even larger margin • Triplets have less margin M. Anerella et al., NIM A 499 (2003). 6500 A 26

  27. Energy increase by 30% (325 GeV) • Previous study, also looked at this for eRHIC (V. Ptitsyn) • Upgrades needed to: • Main magnet PS • Transformers for main magnet PS • Current leads • … • Operation may require: • Crossing angle of 2 mrad • Relaxation in b* Working on definite study – should balance cost with luminosity need.Luminosity guidance helpful. 27

  28. Luminosity and polarization goals Had previously a goal of 60 here.(May reach 60 with source upgrade and electron lenses).

  29. Run-11 p-p luminosity projections 100 GeV [Projections update 11 May 2010.] Expect store polarization of 50-65%, and average store luminosity of up to 301030cm-2s-1. 29

  30. Run-11 p-p luminosity projections 250 GeV [Projections update 11 May 2010.] Expect store polarization of 35-50%, and average store luminosity of up to 1001030cm-2s-1. 30

  31. Spin plan update projections Spin plan update, 06/09/2008 [Assumes 10 week p-p operation every year.] 31

  32. RHIC 5-year outlook polarized protons b*, collimation b*, 56 MHz SRFsource upgrade, e-lenses acceleration near 2/3AGS tune jump,9 MHz, dump pipe, b* b* [Assumes 12 week p-p operation every year.] 32

  33. Summary • Planned upgrades for Run-11: • AGS horizontal tune jump system, acceleration near Qv = 2/3, Beam dump, 10 Hz orbit feedback, 9 MHz rf system, Polarimeter, Spin flipper • Goals (2014): • For 100 GeV: 601030cm-2s-1,P = 70% (needs functioning e-lenses) • For 250 GeV: 3001030cm-2s-1,P = 70% • Main upgrades: • AGS polarization transmission • 9 MHz rf system • Polarized source upgrade • 56 MHz SRF system • Electron lenses • In-situ coating 33

More Related