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PHOBOS 22.4 & 62.4 GeV Cu+Cu

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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. - PowerPoint PPT Presentation
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PHOBOS 22.4 & 62.4 GeV Cu+Cu Peter Steinberg Brookhaven National Laboratory March 16, 2005
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Page 1: PHOBOS 22.4 & 62.4 GeV Cu+Cu

PHOBOS22.4 & 62.4 GeV Cu+Cu

Peter SteinbergBrookhaven National Laboratory

March 16, 2005

Page 2: PHOBOS 22.4 & 62.4 GeV Cu+Cu

PHOBOS Cu+Cu 200 GeV

Page 3: PHOBOS 22.4 & 62.4 GeV Cu+Cu

The Week in Chipmunk 2

62.4 GeV 22.4 GeV

Page 4: PHOBOS 22.4 & 62.4 GeV Cu+Cu

Progress in 62.4 & 22.4 GeVGoal: 250M

Expect: ~100M

Page 5: PHOBOS 22.4 & 62.4 GeV Cu+Cu

Progress in 62.4 & 22.4 GeV

Page 6: PHOBOS 22.4 & 62.4 GeV Cu+Cu

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

Page 7: PHOBOS 22.4 & 62.4 GeV Cu+Cu

Up until Reboot

Bunch Number

Page 8: PHOBOS 22.4 & 62.4 GeV Cu+Cu

After Reboot

Bunch Number

Page 9: PHOBOS 22.4 & 62.4 GeV Cu+Cu

Trigger Rates

Page 10: PHOBOS 22.4 & 62.4 GeV Cu+Cu

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

Page 11: PHOBOS 22.4 & 62.4 GeV Cu+Cu

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

Page 12: PHOBOS 22.4 & 62.4 GeV Cu+Cu

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

Page 13: PHOBOS 22.4 & 62.4 GeV Cu+Cu

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 PRLPhys. Rev. Lett. 94, 082304 (2005)


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