results from rf cogging sessions on nov 20 to 23
DESCRIPTION
Results from RF cogging sessions on Nov 20 to 23. A. Di Mauro, M. Krivda. Some basic numbers. Master RF = 400.788766 MHz 1 bucket = 2.4950799 ns 1 bunch = 10 buckets 1 ORBIT = 35640 buckets Revolution period 88.92464815 m s BPTX-A – IP2 = 145996.5 mm BPTX-C – IP2 = 145286.5 mm - PowerPoint PPT PresentationTRANSCRIPT
Results from RF cogging sessions on Nov 20 to 23
A. Di Mauro, M. Krivda
Some basic numbers
Master RF = 400.788766 MHz1 bucket = 2.4950799 ns1 bunch = 10 buckets1 ORBIT = 35640 bucketsRevolution period 88.92464815 s
BPTX-A – IP2 = 145996.5 mmBPTX-C – IP2 = 145286.5 mm(TOF = 2.37 ns)
BPTX-A cable delay = 800.4 ± 0.1 ns (i.e. 196.76 ± 0.03 m with Vp=0.82*c)BPTX-C cable delay = 670.8 ± 0.1 ns(i.e. 164.89 ± 0.03 m with Vp=0.82*c)
BPTX-A (on beam-1)
BPTX-C (on beam-2)
FOR BUNCHES CROSSING IN IP2 BPTX-C ARRIVES 127.23 ns BEFORE BPTX-A
Cogging with BPTX• Bucket 1 is defined as the 1st after the 3 s empty
abort gap (from 34442 to 35640)• Bunches in bucket 1 of the two beams collide in IP1
and IP5• By delaying the beam 2 injection bucket by ¼ turn
the IP is displaced by 1 octant (e.g., beam-1 bucket 1 collides with beam-2 bucket 8911 in IP2)
• Cogging strategy: fix beam-1, adjust position of beam-2 bucket 1 so that buckets 1 collide in IP1/5 ->T = 0 in IP1/5, T= 66.693453 us in IP2
Cogging with BPTX
• Two scopes installed close to rack C20 (where BPTX signals are fed to BPIM – Beam Phase and Intensity Monitor – boards), in front of CTP rack
ORB1BC1ORB2BC2ORB from TTC MAIN
ORB from TTC MAINBC from TTC MAINBPTX-ABPTX-C
First measurement with single beam
BPTX1-ORB1 = 7.89646 usBPTX2-ORB2 = 42.17682 usORB2-ORB1 = 2.573 usT = (BPTX2-ORB2) + (ORB2-ORB1) – (BPTX1-ORB1)
T - 66.93453 = -29.840092 us -> IP rotated anticlockwise by ~ 1/6 orbit wrt IP1/5
Second try with single beam
BPTX1-ORB1 = 7.89646 usBPTX2-ORB1 = 74.5914128 usT - 66.93453 = 0.0015 us
Beam-2 rotated clockwise by 29.84115 us
…and finally with both beams
Beam-1 bucket 1
Beam-1 bucket 1
…and finally with both beamsFine tuning for ATLAS/CMS, ~ 1 ns correction
…and finally with both beamsFine tuning for ATLAS/CMS, 1 ns correction
..and in ALICE
Beam-1 bucket 1
Beam-2 bucket 8911 Without cable/TOF delay correction
..and in ALICE
Beam-1 bucket 1
Beam-2 bucket 8911
With 127.23 ns cable/TOF delay correction
<- Measured also by CMS