LHC 2012 - latest news

Week 21: Machine coordinators: Barbara Holzer, Ralph Assmann

Plan for the week: Luminosity production

 

Date

Summary

Link to report from morning meeting

Monday 28 May

  • 1:13 - 2:27 stable beams Fill 2670, 1.5e11 average bunch intensity, Peak lumi: 6.6e33 cm-2s-1, Integrated lumi ~ 27 pb-1, Emittance in collision ~ 2.2 μm rad

  • 2:27 Fill 2670 dumped by power converter problem of RQTX2.L8 (Free wheel diode fault)
  • 5:33 stable beams Fill 2671, 1.5e11 average bunch intensity, Peak lumi: 6.4e33 cm-2s-1, Emittance in collision  ~ 2.3 μm rad

9:00 meeting

Sunday 27 May

  • Cryo recovery Pt 8
  • 22:00 cryo recovered
  • 22:42 – 23:14 problem with RF module 2B2
  • 23:14 injecting

9:00 meeting

Saturday 26 May

  • 0:50 Dry dump to verify LBDS
  • 3:21 Fill 2668 dumped by losses at TCLA.C6R7.B1 at the very beginning of collisions BP (bunch intensity a bit too high? average 1.53e11)
  • cavity 7B2 low level problem
  • 6:24 Fill 2669 stable beams, average bunch intensity 1.5e11, peak lumi: ~6.5e33 cm-2s-1.
  • 14:37 Beams dumped by operation due to cryo problem: Refrigeration unit (QURC) down in point 8. Integrated lumi: 132 pb-1.
  • 16:28 Access to US85 to reset the magnetic axle bearing of QURCB.
  • 17:20 ALICE access (dipole and compensator had been ramped down before).
  • 22:08 End of ALICE access.
  • Pressure rise in the triplet zone 7.4L1.X (no pump in the segment and triplet warming up).
  • Cryo recovery ongoing.

9:00 meeting

Friday 25 May

  • 1:06 Fill 2662 dumped in adjust, high beam losses (bunches at the end of trains), average bunch intensity 1.55e11.
  • 3:44 – 15:04 stable beams Fill 2663, 1.51e11 average bunch intensity, Peak lumi: 6.5e33 cm-2s-1, Integrated lumi 167 pb-1
  • 14:30 – 15:00 tune scan B2
  • 15:04 beam dumped for scheduled access: Atlas gas leak; LHCb; Pt 6 interlock BPMS cabling check and attenuators; Vacuum Pt 4 to repair a pumping group at 14R4; TOTEM LVDT bypass activated and B2 injection BIC channel disabled.
  • BBQ, OFSU, LBDS and MKI problems
  • RQ6.R1 tripped due to a spike in U_res

8:30 meeting

Thursday 24 May

  • 00:41 Dumped by interlocked BPM in IR6.
  • 01:22 Problems with TCL.5R1.B1 (recurrent issue). Disabled the resolver check on lost steps.
  • 02:11 Injection.
  • 03:53 Stable beams. Peak lumi: 6.0e33.
  • 05:14 RB.A45 QPS trip. Recovery…
  • 09:00 Access for IR8 triplet. Other accesses in shadow.
  • 14:40 BPM interlock test
  • 17:34 Fill 2660 stable beams (no more 'private' IP8 bunches), 1.48e11 average bunch intensity, peak lumi 6.1e33 cm-2s-1, integrated lumi 24.5 pb-1
  • 18:47 beam dumed by SIS BLM HV interlock (communication problem between BLM CPU and CMW).
  • Access for Atlas gas leak

8:30 meeting

Wednesday 23 May

  • 04:24 Operator beam dump.
  • Refill for physics. Delays due to problems with SPS bunch length.
  • 08:55 Fill 2653 stable beams, 1.40e11 ppb, 5.6 1033 cm-2s-1peak lumi, 11.6 pb-1 total lumi delivered.
  • 09:31 Dumped by collimator interlock on TCDD (injection movable mask/collimator) for beam 1.
  • 10:55 Access for replacement of power supply for PXI rack.
  • 11:41 Access finished. Recovering TCDD and TDI positions for beam 1. In shadow: QPS board swap on RQTL11.L5B1 and RCD.A45B1.
  • 13:02 Injection. Steering TI2 and TI8,
  • 14:05 problems with BPM interlocks from LSS4 and LSS6. PS and SPS need to readjust the beam.
  • 14:15 TOTEM interlock for injection.
  • 17:36 Injecting slightly higher bunch intensities: 1.47e11 average. Emittance from SPS: ~1.8 micron (on 12 b).
  • 18:41 Stable beams. Peak lumi: 5.6e33.

8:30 meeting

Tuesday 22 May

  • 00:42 Collimator issues: RBAC access problem.
  • 01:09 FBCT issue: reboot.
  • 01:27 Interlock from TCL.5R1.B1: missing steps.
  • 02:49 Again FBCT issue: reboot.
  • 03:05 Injection
  • 04:03 Interlock from TCL.5R1.B1.
  • 06:19 Injection.
  • 08:09 Ramp.
  • 08:48 stable beams fill 2651. Peak Luminosity: 5.8 1033 cm-2s-1.

8:30 meeting

Monday 21 May

  • Access for switching temperature probe DFB L7.
  • In shadow: Access for fire detection equipment at point 1. ATLAS access.
  • 12:26 Injection. Interlock from TCL.5R1.L1: lost steps.
  • 13:41 Stable beams. 5.9e33 lumi. 123MJ. Low losses in intensity.
  • 20:59 End of fill. Trip of IT.R1. Validation of inner triplet in R1 needed due to spurious signals in PM. ATLAS intervention.
  • 23:33 Triplet check complete. Signals are normal and observed spike is due to a slight current imbalance between the Q1 and the Q3 of the triplet. Proceed.

8:30 meeting