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Explore polarization transmission efficiency with near integer working point June 10, 2009

Explore polarization transmission efficiency with near integer working point June 10, 2009. Mei , Don, Angelika, Wolfram, Haixin, Yun, Al, Greg, Michiko, Kevin, Rob Fulvia, Vadim, Guillaume, Thomas, Todd, Vincent, Carl, Steve, Anatoli. Motivation. Goal:

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Explore polarization transmission efficiency with near integer working point June 10, 2009

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  1. Explore polarization transmission efficiency with near integer working pointJune 10, 2009 Mei, Don, Angelika, Wolfram, Haixin, Yun, Al, Greg, Michiko, Kevin, Rob Fulvia, Vadim, Guillaume, Thomas, Todd, Vincent, Carl, Steve, Anatoli

  2. Motivation • Goal: • Look for new working points which 100% polarization can be achieved • Candidate: • Near integer: > 0.94 • RHIC pp design working point: 0.81 • Setup: pp94nearInt • Blue wp: Qx=27.88, Qy=0.955 • Yellow wp: Qx=27.82, Qy=28.81 11/16 11/14 Py 15/16=0.9375 old working point 13/14 11/12 current working point 7/8 7/10 3/4 9/10 5/6

  3. Preparation • Build pp94nearInt: • Steve, Al, Don • Ps preparation: Don, Carl, Chaofeng, … • Exam pp94nearInt ramp with no beam: 2 3-hours APEX sessions • Failed ps • QPA problem • Blue ups problem • Switch mains coefficients: Carl • Prepare BBQ and tune/coupling feedback • Michiko, Al, Yun, Kevin, … • Finalize pp94nearInt • Guillaume, Vincent, Steve

  4. What have been achieved? • Lowered Qy to below 0.9 to establish circulating beam • Set Blue Qy to ~0.94 to establish good lifetime at injection. Orbit correction in Blue with near integer tune was excised. Good orbit was established. • Spent ~ 3 hours at injection to setup tune feedback in Blue for near integer tune. Al hardwired the coupling correction to zero in his code to force coupling feedback off as Yun suggested • Yun measured coupling angle in Yellow at injection • Both beams reached top energy after two ramps which pushed beam to one stone per ramp. Orbit distortion along the ramp ~7-8mm rms. Orbit at store was corrected. • Spent 3 ramps to do orbit correction along the ramp. Permit was pulled for all the ramps due to instability right before store stone. No polarization measured.

  5. Summary of ramps

  6. Summary of ramps

  7. First ramp both beams up to 250 GeV Yellow loss due to instaility

  8. Blue Beam, Orbit and Tune

  9. Yellow Beam, Orbit and Tune

  10. Plans • Another 8-12 hour session • Correct chromaticity and make beam survive to store stone • Improve orbit correction as well as beam transmission efficiency • Measure polarization • measure polarization as function of Qy from 0.935 to as high as possible. This may require couple of iterations of optimizing ramp to correct orbit • Increase # of bunches to > 28 bunches per ring • measure polarization along the ramp if time allows

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