report from 8:30 meeting
Tuesday 8th December
8:30 Summary for
Monday 7th December
a) Loss of cryo maintain in sector 81 led to dump of stable beams.
b) Electrical perturbation at 04:25 during recovery. Loss of warm compressor
in IR4. Magnet trips. Other effects on machine elements.
c) Recovery estimated between 22:00 and 24:00.
8:30 Summary pptx for December 6
Sunday 6th December
00:00-02:30: Four bunch setup.
a) 1.5e10 p in beam1 in 4 bunches. Fully protected
machine. 25h beam lifetime. Correctly dumped.
b) At 01:32: Two beams with each 4 bunches stored.
B1: 1.4e10. B2: 1.5e10.
c) Dump tests show normal loss patterns both for bunched and unbunched beams.
02:30-06:30: Injecting for stable beams. Finally successful
around 6:30 after resolving a lifetime problem with beam 2. 4 on 4 circulating and colliding with reasonable lifetime for
06:55-11:00: STABLE BEAMS!
First time for LHC! 450 GeV collisions for the experiments.
11:00-22:30: End of fill, recovery.
a) Stable beam was dumped due to BCT server reboot.
b) Switch off of all LHC sectors at 14h15.
c) Access from 16:00 to 18:00.
d) Pre-cycle and recovery.
22:30-00:30: STABLE BEAMS.
Back to stable beams and 450 GeV collisions with increased bunch intensities
of about 6e9 protons per bunch.
01:00-02:00: Work with
a) LHCb spectrometer non-closure (0.8mm) corrected.
b) Then RF problems and no beam.
01:00-06:00: Work with Beam1.
a) Beta beat studies and correction: Dipole b2, IR8 and IR2. Improvement for
most arcs in horizontal beta-beating for beam1. Clear big error in IP7
b) 100 beam dumps to verify change in dump kicker software.
07:00-09:30: Prepare and perform pre-cycle.
09:30-10:00: Prepare injection.
10:00-12:00: Beam2 only. Correct tunes and chromaticity.
Bring on ALICE spectrometer. Establish reference. Interrupted by several
interlocks from RF. ALICE spectrometer non-closure (0.35mm) corrected.
12:00-14:00: Golden orbit and IR steering.
a) Beam-beam separation minimized in all IR's.
b) ALICE solenoid switched on.
c) Golden orbit loaded.
d) Orbit in cleaning insertions corrected to Sunday reference (collimatio
e) Software interlock on dipole correctors activated (for STABLE beam mode).
14:00-16:00: Reestablishing collimation.
a) Collimator settings reloaded. No reoptimization required (very good
machine and collimator reproducibility). Loss patterns OK. Injection OK (~70%
b) Identified lifetime reduction from transverse damper. Lifetime with
collimators in nominal position and transverse damper off reached >25h.
c) BLM beam loss spectra recorded with collimator scans.
d) Most collimator position interlocks activated (except injection and dump
16:00-17:00: RF work.
16:00-20:00: Dump and injection protection.
a) TDI's set up.
b) TCDQ and IR6 TCSG set up.
c) Tests for asynchronous dumps. OK.
d) Position interlocks on 2 TDI, 2 TCDQ, 2 IR6 TCSG, 2 TCLIA, 2 TCLIB.
e) ALICE solenoid inverted.
20:00-23:00: Trip of B24.R1. Recovery, pre-cycle and injection
23:00-00:00: Reestablish reference. Final dump protection
9:00 Summary pptx for December 4
Friday 4th December
07:30-12:00: Aperture studies continued. Stopped by
beam-induced quench in cell 15R2 (injecting into orbit bump). Beam intensity
was around 4e9 p.
12:00-13:00: Prepare access (advanced this compared to
13:00-17:00: Access and other work:
a) Access for undulator, TOTEM, wire scanners, LBDS, RF damper and QPS.
b) Intervention on PS magnets.
c) RF changed configuration: work with half the number of cavities and about
the same total voltage (7 MV instead of 8 MV) to reduce power dissipation on
the klystron collectors.
d) Further analysis of tune ripple observation.
17:00-19:00: Pre-cycle. No problems, except trips
RSF2.A78.B1 and RSD2.A78.B2.
19:00-20:00: Injection set-up. Unable to turn RF power on
for module M1B1 for beam 1.
20:00-21:00: Beam 2:
a) Inject and correct beam 2.
b) 20:30 -> For the first time two bunches in a single
LHC beam (total intensity 8e9 p in beam 2).
c) Systematic checks for instrumentation and beam dump. All OK.
21:00-22:00: Beam 2:
a) Undulator successfully at 200A, no light seen yet.
b) Switching on LHCb spectrometer to nominal 2106.371 micro-rad = 5850A.
c) RF triggered beam dump. RF problem related to 18 kV distribution problem.
22:00-01:00: Work on RF. Injection set-up.
8:30 summary pptx for
23:00-02:00: IR8 aperture study.
Looks OK for LHCb. To be analyzed.
05:00-08:00: Beta beat studies.
Beam 1 correction had a positive effect. Need to understand IR7 results more
carefully for Beam 2.All trims and tunes reset to initial settings.
08:00-13:30: TDI and LBDS studies.
a) Ring injection protection set up for beam2 (+-6.8sigma for TDI, TCLIA, TCLIB
plus TDI angle). Protection verified with injection failure tests with beam.
Over-injection mode tested: requires some BLM interlocks disabled for this
b) Dumpline trajectories verified for beam 1 and beam 2. Dump failure tests
c) IR6 aperture scans with bumps for both beams. No sign of abnormal aperture
13:30-15:00: Beam instrumentation checks.
Q/Q' and coupling measurements.Tune stability issue H plane: tune walks
around at 0.001 level.
15:00-23:00: IR aperture checks.
a) CMS aperture scan OK.
b) ALICE aperture scan OK.
c) In ATLAS the V plane is OK (respectively similar to the other
experiments). The H plane is 'different' from all other IRs.
ATLAS dumped with the BCM on both beams, while the machine BLMs never gave
any significant signal (in the V plane the BLMs gave the usual signals): both
beam1 and beam2. Went to relatively large amplitudes, even though less than
in other IRs. Be careful not to draw hasty conclusions.
00:00-07:30: Separation bumps and crossing angle.
a) All bumps switched on individually. No problems (polarity etc).
Non-closure and dispersion verified.
b) Luminosity scan knobs tested successfully.
c) Finally at 06:25 all separation bumps and crossing angles (nominal
injection values) switched on and both beams injected with NO major losses.
IP8 losses not related to IR setup (stayed unchanged). No sign of problems
with cross-talk from MCBX’s (nested IP correctors).
d) Orbit saved and bumps removed.
8:30 summary pptx for December 2
01:23 18 kV drop -
Meyrin site. LHC off - cryo OK. Several accesses completed by noon. QPS
tests. Issues with recovery as filters are put onto electricity lines,
tripping various circuits. Magnets switched off for filters in further
sectors. ALICE solenoid also tripped. Beam back at 22:30. IR8 aperture
8:30 summary pptx for December 1
Tuesday 1st December
synchronization tests in the morning. Access at midday. Beam back into the
LHC at 18:00.
8:30 summary pptx for November 30
Monday 30th November
Alice, Atlas and CMS
solenoids successfully brought on - orbit and coupling corrected. Aperture
and kick response measurement overnight. Wirescanners successfully
8:30 summary pptx for November 29