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PHOBOS 22.4 & 62.4 GeV Cu+Cu

PHOBOS 22.4 & 62.4 GeV Cu+Cu. Peter Steinberg Brookhaven National Laboratory March 16, 2005. PHOBOS Cu+Cu 200 GeV. The Week in Chipmunk 2. 62.4 GeV. 22.4 GeV. Progress in 62.4 & 22.4 GeV. Goal: 250M. Expect: ~100M. Progress in 62.4 & 22.4 GeV. Problem with Bunch Mask.

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PHOBOS 22.4 & 62.4 GeV Cu+Cu

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  1. PHOBOS22.4 & 62.4 GeV Cu+Cu Peter SteinbergBrookhaven National Laboratory March 16, 2005

  2. PHOBOS Cu+Cu 200 GeV

  3. The Week in Chipmunk 2 62.4 GeV 22.4 GeV

  4. Progress in 62.4 & 22.4 GeV Goal: 250M Expect: ~100M

  5. Progress in 62.4 & 22.4 GeV

  6. Problem with Bunch Mask • Yesterday afternoon, we were getting ~120 Hz of collision trigger • Only recording ~70 Hz to tape • Everything appeared to be timed in properly • Don Barton applied 5ns corrections for going to 22 GeV (vs. <1 ns for 62.4 relative to 200 GeV) • Problem traced down to using an older bunch mask file (no change since Saturday) • Server rebooted today around 9:45am

  7. Up until Reboot Bunch Number

  8. After Reboot Bunch Number

  9. Trigger Rates

  10. Updated Expectations for 22.4 GeV • Might expect initial rates of 500-600Hz • O(10000)/(2*10) (beta* and gamma) • We only accept ~25% of this: 125-150 Hz • This is approximately what we saw, accounting for the missing factor of ~2 • If we get 120 Hz and we get • 6+24+8 = ~38 hours run (6pm 3/22 - 8am 3/24) • Then 38 hours x 50% uptime = 8.2M events • Adequate for our needs

  11. ZDC Rates - not sure what is going on...

  12. Special Requests for 62.4 GeV • Polarity flips • 0: Thurs 3/17 9am • A: Thurs 3/17 1pm • PHOBOS magnet induced unexpected “field-off” run • Only got ~200k physics events • Not enough for physics groups

  13. Expectations for 62.4 GeV • 12 Days, 50% uptime • 450 Hz average trigger rate • This gives about 250M events • Pushes out to ~5 GeV in pT - to match PRL Phys. Rev. Lett. 94, 082304 (2005)

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