LHC “progress” Wednesday 29 th April 2015 Coordination: Mike Lamont, Wolfgang Hofle

Morning 07:30 beam eventually back in after LBDS switch change/accesses/Q5.LR7 etc 09:00 cancel TDI set-up to allow resolution of inhibiting BLM problem in the SPS preventing start of NA physics 450 GeV – testing LHC tune chirp on beam 2 (Marek, Daniel, Maria). ADT is working. Tried tune chirp since 9:20h on B2. For now tune chirp is not working. Access needed to check where the problem is. 10:10 Ramp Flat-top: – K-modulation – Initial BPMSX tests – bumps – BSRT

Midday – major event 1 - BA6: 11:28: We saw an emergency stop alarm in BA6, the button was pushed by an EN-CV technician on-site who saw smoke coming from an electrical breaker. – This breaker was later confirmed to be for the power supply for HIRADMAT. 11:46 The emergency stop cut all power, including to the cooling towers of BA6, and worse yet the ”WSSPS” pumping station from SIG that also supply the CRYO in SM18 and the pressure for the whole SPS. – We saw the WSSPS alarm immediately and followed the temperature live with the cryo operator, degree by degree.. The electrician was literally running to try and switch back on the WSSPS in time, but was less than a minute late! 11:56 CRYO lost in SM18. 12:15 Most cooling systems up and running again. The breaker that caught fire was pulled out, to allow for a quicker restart since HIRADMAT is not to be used before Friday. Jesper Nielsen

12:30 Major event 2 12:27 All cooling distribution circuits for the SF6 cooling towers stopped. We actually managed to restart the most important remotely, but the CRYO had interlocked immediately on a cooling fault. We lost the CRYO and also the compensator in LHC6. Our first idea is that we tripped on a low level in the cooling towers, looking at the trends we see a level going down steadily since yesterday at 20h. But that has to be verified with CV. 12:30 Called in the expert from EN-CV, he will go on-site immediately. 12:58 The compensator was put back in service and all systems are good to go again. Jesper Nielsen

28/4 Primary water stop in point 6 Failure of the filling valve: the axle of the valve disconnected from the actuator Serge Deleval

28/4 Primary water stop in point 6 One low level alarm based on the analog measurement of the basin level Two level switches which is stopping the whole system Why no alarm before the stop ? The two level switches was activated at ≈1600 mm (nominal 700mm) higher than the low level alarm The good functioning of the level switches at the good level was validated the 5th of November 2014 during the maintenance The level switches partially detached from their support. Action taken: the filling valve was temporarily repaired Increased to low level alarm to 1800 mm Action foreseen during TS1: Replace the filling valve Check the level switches Serge Deleval

Access in shadow of cryo recovery Update on the BLM system: – access to replace filter-box in B6R2 – update on the Connectivity Check limits (part of the Sequencer BLM Sanity Checks) calculated with modulation data collected since Easter. Aim is to reduce the number of false positives (seen many especially in points 6 and 7). ADT to investigate chirp issue

Wednesday AM 00:00 Cryogenics back QPS problem: 4 QPS controller on the same crate are stuck (DQGPU.05RR73) – Fixed by piquet (Stephen Pemberton) 00:35 Precycling 01:45 Beam back ULO scan 04:00 Lost CRYO conditions in MSR1. – wrong temperature measurement that caused a valve on a DFB to close. Quick recovery. Precycle need 06:00 Injecting for interlocked BPM set-up

Interlocked BPMs Summary of this Tuesday morning tests at top energy with pilot – The new firmware was tested without the FESA class running and the BIS reacts correctly when sending dump signals from the firmware. – The FESA class was started and no spurious dump were observed so far. – The calibration of B1 R was tested using +/- 0.5mm orbit bumps. Test without beams during afternoon: – Using calibration signals – Check logging and post mortem buffer (capture data for IntBPM) Ongoing (Wednesday) morning: – Scrape nominal bunches at injection to validate the new high/low sensitivity ranges – Orbit bumps or change the MPP limit to make sure the system works correctly – Full qualification with MPP (procedure specified by Jan) – Start to run the interlock process unmasked Thibaut Lefevre and team

ULO scan this night More-or-less as measured on Sunday Delphine/Stefano

Longitudinal blow-up blues Currently Heiko implemented a long blow-up in the PS for the probe so that the bunch length at extraction of SPS is 1.4 ns to 1.5 ns at SPS extraction to best mimic a nominal bunch in LHC, as requested by Philippe. – 1.4 ns coming out of SPS – ~1 ns after capture Last Thursday night, we have tested an upgraded version of the LHC long. blow-up. The test was not conclusive The problem was traced to the algorithm generating the phase noise excitation and it has been solved. So we are now ready for a second test. The plans: – First a test at 450 GeV (1 hour) – Then, but not necessarily just after the previous test, a first ramp with the new algorithm – Our RF controls expert must be present. Can we have a timeslot on Wednesday or Thursday? Philippe.Baudrenghien

INCOMING

MUFOs/ULO Beam screen now at around 80 K (second warm- up – prolonged this time) MUFOs appear to be supressed by beam screen warm-up – But perhaps not definitively Some indications of vertical movement of restriction Questions: – Does restriction move with BS temperature? – How does restriction behave with higher intensities?

Machine protection Markus Zerlauth

Today Tests of BPMSX (interlocked BPMs) - ongoing Measure 15R8 aperture - beam screen cold Global aperture measurement Longitudinal blow-up TDI set-up

Batch-by-batch blow-up Philippe would also like to proceed with re-commissioning of the batch-by-batch long blow-up in LHC which would permit to have bunches of different distribution and use this for method for momentum collimation set-up. They discussed this with Stefano. In order to get the batch-by-batch mode for the long. blow- up working Mic Jaussi would need 30 minutes to 1 h to qualify his software with probe beam at 450 GeV before any attempt to use it operationally. Can ? e slot this in some time perhaps in parallel to the ULO scans on beam 2. Mic said he is available and I think it can be first tried with beam 1.