Summary week 31 Week 31 G. Arduini & O. Brüning 02.08.-09.08. 8:30 meeting

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 = 4 1030 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 = 1.7 1030 cm-2 sec-1  ca. 40% efficiency (wrt to scheduled time);  total luminosity ca. 1080 nb-1 8:30 meeting

Week 31 8:30 meeting

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 8:30 meeting

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 8:30 meeting

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

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 2.8 1030 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; 8:30 meeting

Tuesday 3.8. Beam intensities over fill– Losses for Beam2 higher than for Beam1 after inverted sign of tune split 8:30 meeting

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 3.0 1030 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; 8:30 meeting

Wednesday-Thursday 4-5.8. End of physics at ~11:00 after 18.5 hours ~120 nb-1 8:30 meeting

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) 8:30 meeting

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

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 8:30 meeting

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. 8:30 meeting

Friday 6.8. 04:00: Fill 1263 Physics fill with 25 nominal bunches; No tune split and DQ = +2 10-3; Emittances: ex1 = 3.4 mm; ey1 = 3.0mm; ex2 = 3.0 mm; ey2 = 3.2mm; Initial peak luminosity of 2.7 1030 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 8:30 meeting

Friday 6.8. Feedback during ramp and squeeze: 8:30 meeting

Friday 6.8. Relative bunch intensity drops for Beam1 and Beam2: Fill 1263 Giulia Papotti (BE/OP/LHC) 8:30 meeting

Friday 6.8. Relative bunch intensity for Beam1 and Beam2: Fill 1263 no Q split & DQ = 2 10-3 versus Fill 1262 no Q split giulia papotti (BE/OP/LHC) 8:30 meeting

Friday 6.8. Relative bunch intensity drops for Beam1 and Beam2: Fill 1263 no Q split & DQ = 2 10-3 versus Fill 1257 with Q split giulia papotti (BE/OP/LHC) 8:30 meeting

Friday 6.8. Luminosity over 16 hours:  ca. 50% drop over 15 hours ~90 nb-1 8:30 meeting

Friday 6.8. Fill terminated at 19:00:  ca. 1000 nb-1 ± 10%  Champagne!!! 8:30 meeting

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 3.1 1030 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 8:30 meeting

Saturday 7.8. Initial Luminosities 8:30 meeting

Saturday 7.8. Lifetimes rising from 5h to above 25 hours over one hour: 8:30 meeting

Saturday 7.8. Fill #1264 dump at 02:14:38: BLM @Q11.L4B1 (2.5 ms threshold triggered) . The comparison with a BLM at TCP.L7 indicates that the loss is real, similar time behaviour

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

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 4 1030 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 3 1030 cm-2 sec-1; 18:50: Loss of Cryo in S34 (loss of communication)  beam dump after 14 hours. 8:30 meeting

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

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 3 1030 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

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

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

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

Monday 2.8. 12:35: Lost access chain in point 2 (PX24 PAD)  Dump after ~14.5 hours ~100 nb-1 8:30 meeting

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

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