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7.7 GeV Low Energy Program

In the second week of the scheduled run, the 7.7 GeV Low Energy Program has been running smoothly with minimal maintenance and downtime. Beam intensities have been improved using hysteresis, but there is still room for improvement. The team is revisiting the beta*=6m development and considering shorter store lengths to further enhance integrated luminosity.

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7.7 GeV Low Energy Program

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  1. 7.7 GeV Low Energy Program • Into second week of four-week scheduled run • No maintenance or APEX; almost always running physics • Short maintenance and APEX sessions this week • Store lengths reduced from 20 minutes to 15 minutes • Successful fix of PHENIX DAQ clock cogging resets • Turnaround times less than 4 minutes to second beam • Currently in physics 75-80% of wall clock time • Operations have maintained a very good rhythm • No radiation safety show stoppers • ATR stability, losses are current limiting factor • Scanning beam parameters during stores • Tunes, octupole settings • Plenty of parasitic data Time Meeting T. Satogata

  2. 7.7 GeV Beam Intensity • A good week, but still room for improvement • Blue intensity is low (70% of yellow), yellow recently down • So what helps? • Beam lifetime has not changed much over parameter scan • Hysteresis appears to help more than physicist tuning Inj tuning AGS L10 Failure PHENIX access Booster MMPS Blue inj tuning beta*=6m development Time Meeting T. Satogata

  3. 7.7 GeV QLI, Hysteresis Tue May 4 • Hysteresis improved beam intensities by about 20% • After a QLI, significant downtime for weather • Slightly reduced yellow lifetime, improved blue lifetime • Yellow lifetime intensity limited, but blue is not Weather Power Dip, QLI, and Hysteresis Ramp Time Meeting T. Satogata

  4. For Your Consideration… • Beta*=6m • Initial development unsuccessful • Showed no luminosity at PHENIX, no improvement at STAR • Confused by additional RF phase changes (a red herring) • Revisiting Tue May 4 daytime to rule in or rule out • Moving to even shorter stores (10 min, 4 stores/hr) • Should give additional integrated luminosity improvement • Requires loss review, impact evaluation by RSC • Perhaps 25-30% integrated luminosity improvement • Collimation is well-optimized • Constant attention from Angelika, operations • Store turnaround time is well-optimized • Little gain to be made here other than minimizing variance Time Meeting T. Satogata

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