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Phobos Cu+Cu Experiment: Progress Report on Collision Data Collection at 22.4 & 62.4 GeV

This report details the progress of the Phobos Cu+Cu experiment at Brookhaven National Laboratory on March 16, 2005, focusing on data collection at 22.4 and 62.4 GeV. The report discusses issues with trigger rates, bunch mask problems, and expectations for data acquisition. Special requests for 62.4 GeV and goals for data collection are outlined, emphasizing the need for adequate event numbers to meet research needs.

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Phobos Cu+Cu Experiment: Progress Report on Collision Data Collection at 22.4 & 62.4 GeV

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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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