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Polarized Protons in RHIC at 500 GeV

Polarized Protons in RHIC at 500 GeV

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Polarized Protons in RHIC at 500 GeV

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  1. Polarized Protons in RHIC at 500 GeV Mei Bai C-A Dept. BNL

  2. RHIC pp design parameter Achieved performance for Physics Runs

  3. Luminosity performance • Need a factor of 3 to achieve the design luminosity goal • Current luminosity limit • Beam-beam interaction • Cause emittance growth through non-linear resonance and other effects. • Current pp workpoint at (0.695,0.685) hits the limit by 3Qx resonance and 10Qx,y • E-cloud: possibly an additional source of emittance growth

  4. Polarization performance • Achieved 100% polarization transmission efficiency from injection to 100 GeV • Much stronger spin depolarzing resonances from 100 GeV to 250 GeV

  5. RHIC intrinsic spin resonance spectrum Design goal Achieved Physics Run Intrinsic spin resonance Qx=28.73, Qy=29.72, emit= 10

  6. FY 2006 RHIC pp 250 GeV development(one week) • Explore polarization transmission to a beam energy of 250 GeV • Inspect the luminosity aspects (witn 2 collisions) • Store lifetime • Total intensity limits • Power supply preparations: 2 shifts • Ramp and polarization development: 8 shifts • Dedicated polarization studies: 2 shifts • Dedicated luminosity studies: 2 shifts • Contingency shifts: 2.5 shifts • Total required: 16.5 shifts or ( 5 days +1.5 shifts)

  7. Overview of RHIC pp 250 GeV development Yellow ps lead flow problem Fix the rf ring to ring synchro Booster problem, ps problem Ps problem, access control problem Weather related down time ps problem, access control problem Quench recovery ps work Booster problem Booster problem

  8. What have been achieved? • Blue beam was first accelerated up to 250 GeV at the end of FY2006 pp RUN

  9. pp in blue accelerated to 250 GeV with 45% polarization 250 GeV injection Polarization at 250 GeV Polarization at injection

  10. What have been achieved? • Blue beam was first accelerated up to 250 GeV at the end of FY2006 pp RUN • Polarization measurement as a function of beam energy identifies the location of polarization loss

  11. Resonance around 138 GeV RHIC pp polarization ramp measurement

  12. Remaining issues of RHIC pp 250 GeV development • Exam the polarization transmission efficiency in Yellow • Systematic study of polarization along the energy ramp as function of orbit distortion and beam tunes at depolarization resonances beyond 100 GeV • Establish collisions to study the luminosity aspects at 250 GeV • Study the polarization lifetime as a function of beam tunes at 250 GeV

  13. Polarized proton development plan • Luminosity: • Non-linear chromaticity correction: implemented in the current Au-Au Run: Tepikian, Nikolay, Yun

  14. Polarized proton development plan • Luminosity: • Non-linear chromaticity correction: implemented in the current Au-Au Run • 3Qx resonance correction: under study by Johan, Yun, Rama, Mei, …

  15. Polarized proton development plan • Luminosity: • Non-linear chromaticity correction: implemented in the current Au-Au Run • 3Qx resonance correction: under study • Explore new working points • (0.92, 0.93): Christoph • (0.08, 0.07): Wolfram • DA tracking: Christoph and Yun • Spin tracking: Mei, Alfredo • Gradient error correction is also under development by Todd, Jen and Mei during the current Au run • This will be first commissioned during the 2008 pp 100GeV run

  16. Polarized proton development plan • Luminosity: • Non-linear chromaticity correction: implemented in the current Au-Au Run • 3Qx resonance correction: under study • Explore new working points • (0.92, 0.93): Christoph • (0.08, 0.07): Wolfram • DA tracking: Christoph and Yun • Spin tracking: Mei, Alfredo • This will be first commissioned during the 2008 pp 100GeV run • Triplet 10 Hz vibration • 10 Hz orbit feedback • Rebuild tripplet assembly to reduce the 10Hz

  17. 10 Hz orbit feedback Feedback ON feedback OFF Courtesy of Christoph and Angelika

  18. Polarized proton development plan • Polarization: • Improve the orbit control to achieve an orbit distortion of 0.3mm or better during the acceleration from 100 GeV to 250 GeV • Improve the betatron tune and coupling control: Tune/coupling feedback • Snake current setting: spin tune measurement

  19. Need polarized proton to continue the RHIC pp 500 GeV commissioning