Link to report from morning meeting
Monday 18th April
- 00:06 Beams dumped
when injecting third 72b batch for beam 2. Kicker flash-over. Many BLM’s
interlocked, LHCb BCM triggered, several
magnets tripped, vacuum valves closed, cryo lost
in 78 and 81.
- Kicker had a spark
after 1.5 micro-s, while injecting the 72b batch. First 36b part OK,
wrong kick for second 36b part.
- Since then: Recovery. Cryo OK. Vacuum OK. Collimators OK.
Sunday 17th April
- 03:00 injection 336 bunches,
ramp, squeeze luminosity.
- 03:19 Stable beams
#1718. Duration: 9h08.
Peak lumi ATLAS/CMS: 3.8/3.6e32.
Integrated lumi ATLAS/CMS/LHCb/ALICE:
- 11:27 Lost QPS OK on
RQD and RQF sector 3-4. Will reset at the end of next rampdown.
- 12:28 Beam dump. No
orbit data for more than 10 min, SIS interlock.
- 13:29 incorporating lumi scan : IP1 is working and IP5 in H only. IP5-V:
request is out of range.
- 13:39 Access started
in CMS and US15 for ATLAS.
- 14:58 CMS access
- 15:01 Electron stopper
relay at Pt 4 not working => access to UJ43 not possible. Access
- 20:19 Electron stopper
problem fixed (micro switch). Patrol lost. Pt 4 ( sectors 1,9,11),
organize re-patrol within OP
- 21:19 RQD QPS: MQ.33R3
reset by the MPE piquet.
- 21:20 Vacuum valve
fault on VVGSW.160.5L4.B fixed.
- 23:35 Injection
Saturday 16th April
- 00:20 Stable beams.
- 05:15 Beam dump from
electrical perturbation. In stable beams: 4h55
- 08:00 Electrical
perturbation in IR2 ongoing. IR2 compensator (active filter) to be
- 10:30 injection: 336
bunches, ramp, squeeze, lost due to orbit feedback
- 13:00 injection 336
bunches, ramp, squeeze, instabilities, beam lost via BPM threshold
- 16:00 injection 336
bunches, ramp, squeeze luminosity, dump: water failure
- 17:39 Stable beams
#1716. In stable beams: 1h40.
- 19:19 Beam dump. Cut
of demineralised water due to a faulty flow
meter triggered PIC to interlock in S34.
- injection 336 bunches,
ramp, squeeze luminosity, dump: software interlock due to flaky BPM at
Friday 15th April
- 00:00 machine setup
for luminosity run
- 01:58 stable run with
- 11:00 luminosity
leveling in IP8 tested successfully
- 12:11 dump by EIC,
precycle, injection & ramp. In stable beams: 10h13
- 15:49 stable run 228
- 19:18 Beam dump from
power converter (PIC) RCBCH10.L4B2. In stable beams: 3h29
- 20:45 Access for PC
- 22:08 Injection
Thursday 14th April
Interlock tests for ALFA and TOTEM without beam (SPS still down).
SPS available again. Was a problem with radial steering function.
All OK from RF.
Beam losses during lumi-scan. IR6 BPM
interlock (one bunch below threshold).
ATLAS and CMS prepare ramp up. Delays in CMS.
Sector 67 tripped due to glitch on 18kV.
Wednesday 13th April
48 bunches, ramp, squeeze. Luminosity optimisation,
tune scan, rf scan to check robustness of
228b fill dumped just before start of ramp. Reasons: Transverse damper
switched off for chromaticity measurement.
Injecting again for 228b. Beam dump due to losses at injection. SPS had
slight reduction in scraping. PSB checks. Last bunches in batch had very
low intensity. Still losses at 70% of dump threshold for 72b injection.
loss from DC-BCT with ramp 1704, 50ns, 228b. B1: loose 1.5E10 out of
2.8E13 (0.05%). B2: losse 2.0E10 out of 2.8E13
feedback switched off at 13:18:51 (due to a coupling that was larger
than the tune split).
associated with coupled bunch instability started at 13:19:00.
Stable beams. Lumi 2e32 in ATLAS and CMS.
Beams dumped by EIC. BPM studies start.
Post-mortem. LBDS-B1 was armed during BPM calibration which triggered
IR6 BPM interlock (no beam).
SMP configuration changed to be able to obtain the STB and MDI flags at
450 GeV - for the TOTEM/ALFA tests tonight.
Following the losses and observations done on the ramp this morning:
Reduction of the chromaticity by 2 units for beam 1 and beam 2 -
Horizontal plane in the middle of the ramp (see plots). Increased octupoles. Increased damper gain.
BPM studies completed.
RF problems in SPS.
Tuesday 12th April
Access finished in pt 4, quench heaters are charged in cell 32R4.
Access finishing in pt 3.
Injection. 2+1b. Qualification of ramp cycle and new collimator
Collisions optimized (except ALICE). Loss maps.
Injection for scrubbing.
Monday 11th April
beam with 1020b lost after 10 Hz RF trim. Fill 1694.
XPOC to be reset by expert.
Masked QPS_STATE SIS interlocks for RB.A12 and RB.A45.
BPM calibration. BPM good and bad status flips.
M. Andersen: “Did a quick fix of OFSU by changing Fesa threads priorities to allow the Orbit reading
thread more CPU time. Back to the drawing board to determine if more
substantial redesign is needed to make the system more robust.”
LHC.USER.RAMP added to Hypercycle
(RAMP_FAST_2011_V1 BP) for test ramp with 12+1 bunches + probe.
XPOC cleared. Start injection. Reduced ADT vertical gain of B1 & B2
by 50% (old value: 0.04 new value: 0.02). Reduced ADT gain for B1-V by
another 50% to 0.01 (adapted 1st point of ADT - ramp functions as well).
Start ramp. V.Baglin: All pressure interlock
thresholds have been reset to their standard values (1e-7) for this test
Flat top. Ramp was fine. Orbits at flat top recorded for bunch train
(12b) and single nominal bunch. Squeeze and collision not possible due
to required update of TCTH.4L2 function.
RCBH21.R4B2 tripped during ramp down. Reset.
Sector 81 tripped. Bridge B cooling. Access. Give access for discharging
quench heaters in S12 and S45. One QPS team only: do S12 first. CMS
access in shadow.
Access in tunnel point 4 for QPS – one of the electron stoppers
does not move in, preventing QPS intervention. Calling experts. Cannot
get in and out access anymore.
Fire detection is faulty in point 3. Piquet is intervening.
In shadow of access – TCT collimator functions for squeeze and
physics beam processes updated. The nominal sequences are fully
Access team intervention in IR4 completed. Relais