1. Summary week 31 Week 31 G. Arduini & O. Brüning 02.08.-09.08.
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2. Week 31 Operation with Multi-bunch Injection since Thursday 29.07:
13 fills with up-to 120 nb-1 per fill  109 h of luminosity production
 ca. one fill per day; peak luminosity: L = cm-2 sec-1
average fill time of ca. 9 hours (10, 9, 14, 1, 15, 7, 2, 17, 15, 0.5, 2, 14, 2.5)
integrated luminosity: 730 nb-1 (40, 60, 80, 8, 100, 60, 20, 120, 90, 8, 23, 95,25)
 ca. 56 nb-1 /fill;  average luminosity per fill: L = cm-2 sec-1
 ca. 40% efficiency (wrt to scheduled time);  total luminosity ca nb-1
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3. Week 31
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4. Week 31
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
Total
Dump events
Access system fault Pt2
S23 tripped; SIS interlock; Access system Pt1
EOF; PC trip;
EOF; BLM
BLM
Cryo; QPS
Fauls & Interventions
3h Set Up; 3h Access System
5.5h QPS circuit braker; 2hSet Up; 1h BLM Sanity Check; 2.7h Beam Quality Injectors;
3h Set Up; 1h Access System; 0.5h BLM;
3h Set Up; 3h Access
2h Setup; 5h QPS & FGC and Access
10.5h QPS & FGC (Access); 2.5h Set Up
1.5h Cryo; 1.5h Set Up; 3h QPS
Time without Beam [h] 6
10.2
4.5 7 13
48.2
Time ready for beam [h] 18
13.8
19.5 17 11
119.8
Physics [h] 12
2.5
11.5
3.5
14.5
64.5
Efficiency
LHC Ready
67%
18.12%
66.67%
38.89%
67.65%
31.82%
80.56%
55.51%
Scheduled time
50%
10.42%
54.17%
29.17%
47.92%
14.58%
60.42%
38.10%
Comments
Test ramp with 2 nominal bunches
Time invested for injection setup
For periods without studies: ca. 63% efficiency relative to available beam time ca. 45% efficiency per scheduled time
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5. Monday 2.8.
Analysis of the noisy spectra observed at injection and flat-top:
The peaks observed are exact harmonics of 50 Hz extending up to 4 kHz
Instrumental?
The noise seems to be lower in the BBQ pick-up for on-demand measurements
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6. Tuesday 3.8.
Test Ramp for operation optimization with 2 nominal bunches:
Beams lost during squeeze at b* = 7m
Goal for test ramp with 2 bunches for operation optimizations:
A: Damper and tune feedback optimization:
Test of the Q feedback with different PC regulation loop to reduce noise ✔
Transverse feedback tests at injection (0.5 hours) Not yet done
Hump investigations (~1.5 hours) Not yet done
B: Ramp and squeeze optimization:
Incorporate Q and Orbit FB feed forward into ramp. ✔
Establish better end-squeeze to collision sequence/settings. Not yet done
Clean orbit in stable beams (ALICE H plane,..). Not yet done
Check TCTs. Not yet done
Collimator loss maps. Not yet done
Beam dump validation (Dump with RF OFF) Not yet done
8:30 meeting

7. Wednesday 4.8. Tuesday to Wednesday night:
Physics fill with 25 nominal bunches with inverted sign of tune split;
Problems related to losses during over-injection into LHC
Initial peak luminosity of cm-2 sec-1; fill lost due to patrol box in IR1
Wednesday morning: optimization of losses during injection:
Single bunch has very good trajectory and no losses in the TL.
Over-injection with 4 bunches leads to losses that dump the beam  trajectory changes by ca. 0.2mm over all cases (1 to 4 bunch injection); trimmed SPS RF frequency (10 Hz);
Decided to correct trajectory in both lines back to reference using
upstream correctors (0.6mm rms) (origin of change not understood?).
Revalidation of TCDI settings.
Change of some BLM thresholds;
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8. Tuesday 3.8.
Beam intensities over fill– Losses for Beam2 higher than for Beam1 after inverted sign of tune split
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9. Wednesday 4.8. Afternoon: Preparation of new physics fill:
Physics fill with 25 nominal bunches; No tune split between Beam1 and Beam2
15:45: Starting ramp: e1nx = 2 mm; e1ny = 3 mm; e2nx = 2.7 mm; e2ny = 5.3 mm;
17:00: Starting Squeeze;
17:40: Stable Beams; Initial peak luminosity of cm-2 sec-1; Beam lifetimes of 5h going above 25 hours after few minutes and rising to 125h after a couple of hours.
19:30: Roman Pots at 25 sigma;
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10. Wednesday-Thursday 4-5.8. End of physics at ~11:00 after 18.5 hours
~120 nb-1
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11. Thursday 5.8. Go to adjust mode for end of coast study
Swap H/V tunes for B2 (crossing coupling resonance) in order to investigate the feasibility of working point with similar to RHIC in collision. Damper can stand the tune swap but not completely transparent (dip in lifetime and tiny losses)
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12. Thursday 5.8.
Afternoon: Second attempt for a test fill for ramp and squeeze optimization
(2 on 2 bunches)
20:00 RQ10.B2 power converter trip (water fault again)  Beam dump
Incorporate Q and Orbit FB feed forward into ramp. ✔
Establish better end-squeeze to collision sequence/settings. ✔
Clean orbit in stable beams (ALICE H plane,..). ✔
Check TCTs. Not yet done
Collimator loss maps. Not yet done
Beam dump validation (Dump with RF OFF) Not yet done
8:30 meeting

13. Thursday 5.8. New beam process for collision (Mike):
All went smoothly ! Non-closure of the knobs 30 microns in V, 60 microns in H. OK !  To be implemented in the sequence
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14. Thursday 5.8.
Access request from CMS to fix serious problem on their detector
Profited from the access for CMS to fix:
problem on MKB (vacuum interlock configuration)
Module replacement for fixing the spurious interlocks on Q10.R8
Accesses finished by 22:45
Tedious injection process because of an intermittent problem with an 80 MHz cavity in the PS.
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15. Friday 6.8.
04:00: Fill 1263
Physics fill with 25 nominal bunches; No tune split and DQ = ;
Emittances: ex1 = 3.4 mm; ey1 = 3.0mm; ex2 = 3.0 mm; ey2 = 3.2mm;
Initial peak luminosity of cm-2 sec-1 (ca. 10% less then previous fill);
Beam lifetimes initially 5h and above 25 hours after a couple of hours.
Terminated at 19:15  Generated integrated luminosity of ca. 90 nb-1
total luminosity delivered ca. 980 nb-1
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16. Friday 6.8.
Feedback
during
ramp and
squeeze:
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17. Friday 6.8. Relative bunch intensity drops for Beam1 and Beam2:
Fill 1263
Giulia Papotti (BE/OP/LHC)
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18. Friday 6.8. Relative bunch intensity for Beam1 and Beam2: Fill 1263
no Q split &
DQ =
versus
Fill 1262
no Q split
giulia papotti (BE/OP/LHC)
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19. Friday 6.8.
Relative bunch intensity drops for Beam1 and Beam2: Fill 1263 no Q split & DQ = versus Fill 1257 with Q split
giulia papotti (BE/OP/LHC)
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20. Friday 6.8. Luminosity over 16 hours:  ca. 50% drop over 15 hours
~90 nb-1
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21. Friday 6.8. Fill terminated at 19:00:  ca. 1000 nb-1 ± 10%
 Champagne!!!
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22. Friday 6.8. 21:00: Preparing new fill for the night: Fill 1264
21:00: injecting pilot and setup (some delays: mastership, phasing, SPS beam quality [emittance and intensity])  start ramp around midnight
Emittances: ex1 = 2.4 mm; ey1 = 2.3mm; ex2 = 2.4 mm; ey2 = 3.6mm;
01:42: Stable beams:
Initial peak luminosity of cm-2 sec-1;
Beam lifetimes initially 5h and above 25 hours after a couple of hours.
02:15: Beam dump (BLM in Pt4)
Start pre-cycle  machine ready for new injection at
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23. Saturday 7.8.
Initial Luminosities
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24. Saturday 7.8.
Lifetimes rising from 5h to above 25 hours over one hour:
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25. Saturday 7.8.
Fill #1264 dump at 02:14:38: (2.5 ms threshold triggered) .
The comparison with a BLM at TCP.L7 indicates that the loss is real, similar time behaviour

26. Saturday 7.8. 04:15: Problems resetting the machine
Can't close the switch of RQTF.A67B2  called piquet and preparing for access in UA67 (but could closed in the end by M. Zerlauth by doing "Reset System" )
05:24: Sector 67 tripped again:
Quench loop of Q8.R6 which opened again.
As before, a disturbance in the quench signal opens the quench loop.
Diagnosis later points to the power converter as origin for the fault
06:15: A local perturbation in Pt2 stopped the filters of the compensator; TI advises to stop sectors S12 and S23 + the ALICE magnets
 Spent all day in access for QPS and FGC interventions!
8:30 meeting

27. Sunday 7.8. 20:00: Preparing fill for the night: Fill 1266
Emittances: ex1 = 2.2mm; ey1 = 2.3mm; ex2 = 2.0mm; ey2 = 2.5mm;
23:00: Stable beams:
Initial peak luminosity of cm-2 sec-1;
Beam lifetimes initially 5h and above 25 hours after a couple of hours.
Beam dumped after 2h! This time by BLM in IR5.
01:00: Preparing new fill for night:
Emittances: ex1 = 2.5mm; ey1 = 2.5mm; ex2 = 2.6mm; ey2 = 4.0mm;
05:30: Stable beams:
Initial peak luminosity of cm-2 sec-1;
18:50: Loss of Cryo in S34 (loss of communication)  beam dump after 14 hours.
8:30 meeting

28. 07/08/2010 Relative losses for fill 1264 and 1266.
Both with NO tune split.
Both dumped after one hour due to BLM reading
1266 initial losses lower than in any other fill
G. Papotti

29. Sunday 8.8. 21:00: Short Hump study at 450 GeV
No clear evidence yet on effect of offset in cavities on Hump activity.
23:00: Preparing fill for the night:
Emittances: ex1 = 2.7mm; ey1 = 2.9mm; ex2 = 2.8mm; ey2 = 3.9mm;
01:30: Stable beams:
Initial peak luminosity of cm-2 sec-1;
Beam lifetimes initially 5h and above 25 hours after a couple of hours.
04:00: Beams dumped: quench loop of the RB.A67
8:30 meeting

30. Saturday 7.8. Plan for the coming days: Luminosity fills
Next week: Test ramp with 2 bunches:
Check TCTs.
Collimator loss maps.
Beam dump validation (Dump with RF OFF)
Implementation of new beam process for establishing collisions.
8:30 meeting

31. Pending Tests: Requiring access: New BLM Firmware tests
Delay of the PM trigger of the BLM system to be set back  BLM team ready only next week
Loss maps, orbit clean-up and TCT verifications
Requiring access:
Repair COD MCBH.18R7.B2
CV need to replace a motorization of the water valve of the sector 56 - not urgent
Time estimate ~3 hours
Access team to replace oxydized connectors for PAD-PX24 in case of stop (3 hours)
Magnetic probes in the machine for the studies related to the hump - access in point 5 (GA, LW) – 3 hours

32. Monday 9.8. Open Issues: Week 32:
Clogging of CMS cryo filters not yet understood
QPS boards: several boards had to switch from channel A to B.
BLM racks (in buildings SR1 and SR5 and both at position BY02): would like to correct the way the power cable for the multi-plug arrives inside the rack.
Ion pumps in dump line MKB (B2 only 4 out of 8 pumps working; few days intervention, next TS)
Origin – cause of the beam losses that terminated 2 of the best runs (beam-beam?; coherent versus incoherent?).
Bunch-to-Bunch diagnostics would be very helpful!
Week 32:
Malika and Jörg
8:30 meeting

33. Monday 2.8.
12:35: Lost access chain in point 2 (PX24 PAD)  Dump after ~14.5 hours
~100 nb-1
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34. Tuesday 3.8.
Sector 23 Quadrupoles tripped at 07:39 after 7 hours and 20 mins in coast.
Cause being investigated
CMS preparing to ramp down the solenoid for cryo intervention
~50 nb-1

35. Tuesday 3.8. Beam2 losses during over injection:
 Losses for Beam2 too high for operation
8:30 meeting