LHC machine status report Theodoros Argyropoulos Beams Department Operation Group On behalf of the LHC team LHCC 13.09.2017

Outline LHC Run 2017 Timeline Scrubbing run Main achievements Main operational limitations Performance Summary/Next steps LHCC#131 - 13th Sep 2017

The LHC schedule (Apr-Sep 2017) LHCC#131 - 13th Sep 2017

The LHC schedule (Apr-Sep 2017) Reported by M. Solfaroli at the previous LHCC Powering Test + Machine Checkout Recommissioning with Beam LHCC#131 - 13th Sep 2017

The LHC schedule (Apr-Sep 2017) Reported by M. Solfaroli at the previous LHCC Powering Test + Machine Checkout Recommissioning with Beam Today LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline 1st Stable Beams First Stable Beams on Tue 23rd of May  Only 25 days after first injection! 3b + 3b with intensity ~3x1011 protons per beam LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline 1st Stable Beams Intensity ramp up + Commissioning First Stable Beams on Tue 23rd of May  Only 25 days after first injection! 3b + 3b with intensity ~3x1011 protons per beam Intensity Ramp up + commissioning MPS validations, aperture measurements, orbit setup, RF full detuning, crossing angle anti-levelling, optics measurement of the 30 cm beta*, VdM cycle, collimator alignment, Transverse Damper set up, roman pots alignment, beam stability, … LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline 1st Stable Beams Intensity ramp up + Scrubbing Commissioning Scrubbing First Stable Beams on Tue 23rd of May  Only 25 days after first injection! 3b + 3b with intensity ~3x1011 protons per beam Intensity Ramp up + commissioning MPS validations, aperture measurements, orbit setup, RF full detuning, crossing angle anti-levelling, optics measurement of the 30 cm beta*, VdM cycle, collimator alignment, Transverse Damper set up, roman pots alignment, beam stability, … Stable beams with 600 bunches before the start of the scrubbing run LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline 1st Stable Beams Physics Run Intensity ramp up + Commissioning Scrubbing Intensity ramp up continued  2556 bunches before the MD1 run. But multiple beam dumps on fast losses in IR7 (typically 10 - 20 ms risetime) correlated by losses in cell 16L2 LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline Technical Stop1 Physics Run Machine Development MD1 for 3 days followed by the first Technical stop (TS1) Slow recovery for physics  2556 bunches back on Wed 19/07 but dumps due to losses at 16L2 Local bump of 0.5 mm at cell 18L2 to maintain high current in the 16L2 correctors  reduced the steady state losses  smoother fills afterwards MD2 with good availability followed by 2 days of VdM run and 600 bunches low-mu run for ATLAS/CMS LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline Technical Stop1 Physics Run Physics Run Smooth run in the first week of August with 2556b and bumps in Beam screen at 16L2 flushed with temperature increase at 80 K (10/08) known procedure used already in the past Result was not as expected  difficulties in increasing the number of bunches, steps back and forth with only maximum of ~1500b into Stable Beams LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline Technical Stop1 Physics Run Physics Run New beam scheme of 8b4e injected at 04/09  reduced e-cloud effect Smooth and continuous intensity ramp up with this beam up to 1916 bunches (limit for this beam scheme)  operate just above design peak luminosity Only few dumps due to 16L2 losses up to now when tried to increase the beam intensity above 1.21011 p/bunch on average promising for the rest of the run LHCC#131 - 13th Sep 2017

Scrubbing run (6-11 June) Scrubbing is the technique used to mitigate the electron cloud effect: high intensity beam with short bunch spacing is used to “clean” the beam pipe surface and reduce the secondary electrons emission. E-cloud effects: beam degradation (blow-up, losses, instabilities), enhanced heat-load on cryogenics, vacuum pressure rise, etc Important for the LHC: Recovering from EYETS de-conditioning (as observed in 2016) (quick process) Conditioning Sector 12 that has been exposed to air and the MKI2D exchanged before the 2016 ion run e-cloud build-up for LHC 25ns beam LHCC#131 - 13th Sep 2017

Scrubbing run (6-11 June) G. Iadarola et al. LMC 04/06/2017 2820 bunches injected with total intensity 3.4 x1014 p/beam  maximum at LHC (setup needed both at injector and LHC, machine protection checks) Newly installed MKI2D conditioned quickly  not limiting operation Heat-load at Sector 12 (vented during EYETS) reduced to 2016 levels No difficulty from the cryogenics side, instabilities well under control, improved pumping in MKI areas (MKI8D limiting intensity at B2 in 2016) The experience from 2015-16 and actions taken during EYETS clearly beneficial LHCC#131 - 13th Sep 2017

Main achievements Fill 5872 Energy vs β* in IP1/5/8 Enhanced Combined Ramp & Squeeze (CRS) to reach 1 m β* (IP1/IP5) at the end of the ramp, followed by a squeeze to 40 cm (M. Solfaroli, LHCC#130) Crossing angle anti-levelling operational Observed luminosity gain of 3-4 % Steps of -10 μrad at stable beams after 2h, 4h, 8h 150  140  130  120 μrad Fill 5872 ATLAS Luminosity M. Hostettler et al., LMC 28/06/2017 LHCC#131 - 13th Sep 2017

Main achievements P. Baudrenghien et al., LMC 05/07/2017 RF full detuning fully operational since the 4th of June Power independent of the beam current Good agreement between measurements (RF, experiments) and predictions (C. Schwick, J. Boyd, LMC 05/07/2017) Big step towards the HL-LHC era P. Baudrenghien et al., LMC 05/07/2017 Beam gone.. Minimal change in power LHCC#131 - 13th Sep 2017

Main operation limitations: Losses@16L2 Beam dumps due to losses at point 7 related to losses at 16L2 Possible reason: significant air inlet in 16L2 at the pumping port, used for the first time during the EYETS. Same pump for both beam pipes (J. M. Jimenez, LMC 23/08/2017) Appeared already at injection during scrubbing run  aperture measurements showed no restrictions MQ16L2 D. Mirarchi et al., LMC 14/06/2017 LHCC#131 - 13th Sep 2017

Main operation limitations: Losses@16L2 More frequent dumps while ramping up in intensity Solutions in chronological order: Local bump of 0.5 mm at cell18L2 to keep current on the 16L2 ~3A (dumps correlated to low orbit corrector current at 16L2) smoother operation (fills with 2556 b) Warm up of beam screen at 16L2 (known procedure)  difficult to recover the performance (corrector current not helping) Reduced number of bunches and tried to ramp up slowly the intensity  Stability at ~1500b clear intensity dependence Change beam type to 8b4e (BCMS before)  less e-cloud activity LHCC#131 - 13th Sep 2017

Main operation limitations: Losses@16L2 8b4e: reduced e-cloud (induced heat-load) Fast intensity ramp-up to 1916b without any dump with average intensities 1.1x1011 p/b However could not increase intensity more than 1.2x1011 p/b Study is ongoing with additional diagnostics in the cell G. Iadarola Big reduction in the heat load 25ns 8b4e LHCC#131 - 13th Sep 2017

Main operation limitations: Losses@16L2 8b4e: reduced e-cloud (induced heat-load) Fast intensity ramp-up to 1916b without any dump with average intensities 1.1x1011 p/b However could not increase intensity more than 1.2x1011 p/b Study is ongoing with additional diagnostics in the cell G. Iadarola Big reduction in the heat load 25ns 8b4e 8b4e promising for the rest of the run LHCC#131 - 13th Sep 2017

Main operation limitations:B2 dump During mid August, after a series of high intensity dumps following the 16L2 issue, the UD62 dump for B2 developed a nitrogen leak Pack of 6 bottles installed and overpressure in the dump was reduced to preserve the N2 flow as long as possible Not critical for operation at the moment The problem will be inspected and evaluated during TS2 S. Gilardoni et al., LMC 30/08/2017 LHCC#131 - 13th Sep 2017

Performance Machine Availability: 79.3 % Stable beams: 34.6 % 42.0% Operation (other) Machine Availability: 79.3 % Stable beams: 34.6 % Many faults due to beam loss (16L2) 34.6 % Stable Beams 60 faults due to Beam Loss 1.7% Precycle 21.7% in fault (combining overlapping ) Number of occurrences Fault Duration [h] Data from: https://aft.cern.ch/dashboard LHCC#131 - 13th Sep 2017

Performance Luminosity Record peak luminosity of 1.74x1034 cm-2s-1 (2556 b) The slope seems to recover a bit after switching to 8b4e beam scheme. LHCC#131 - 13th Sep 2017

Performance Luminosity Peak Luminosity zoom Record peak luminosity of 1.74x1034 cm-2s-1 (2556 b) 8b4e Peak luminosities around 1.1 x1034 cm-2s-1 per fill with 1916 b of ~1.05x1011 p/bunch LHCC#131 - 13th Sep 2017

Performance Tight but still on track! Integrated Luminosity per fill for the last 1916b 8b4e beam show that we can produce ~0.3 fb-1 in 10-11 hours. With ~56 to 68% in stable beams we can reach the target of 45 fb-1 with present beam conditions (12 days of 2.5 TeV run excluded) Tight but still on track! J. Wenninger LHCC#131 - 13th Sep 2017

Summary Excellent beginning of the Run 1st Stable Beams only 25 days after first injection Record peak Luminosity at 1.7x1034 cm-2s-1 Losses at 16L2 currently limiting operation Studies ongoing Solution during YETS Alternative beam scheme of 8b4e less critical 1916 bunches with 1.05x1011 p/b Operation above design peak luminosity at 1.1 x1034 cm-2s-1 The target integrated luminosity of 45 fb-1 is still achievable. Possible intensity increase in the future (conditioning), although difficult at the moment LHCC#131 - 13th Sep 2017

LHC Schedule Around 11 weeks remaining LHCC#131 - 13th Sep 2017

Next in schedule Continue with 8b4e at the current bunch intensities Possible attempts to gently increase intensity in the coming weeks (after some conditioning?). beta* reduction to 30 cm in preparation Run for the rest of 2017 and 2018  10% gain in integrated Luminosity Decision to restart with 30 cm after TS2 will be taken at LMC Preparation of special physics runs are ongoing High b* at 450 GeV and 2.51 TeV runs Try to advance special runs currently planned for 2018 toward the end of 2017 (?) No special runs in 2018  significant luminosity production to satisfy the Run-­2 targets (90 fb-1) LHCC#131 - 13th Sep 2017

Thank you for your attention LHCC#131 - 13th Sep 2017

BUCK UP SLIDES

Spikes at 16L2 8b4e B. M. Salvachua Ferrando‎ Low number of spikes with 8b4e  no spikes at all for the last few fills Increased number of spike in the fills with higher intensity (also on the one after with reduced intensity) All dumps in the last period from Beam 1 LHCC#131 - 13th Sep 2017

E-cloud with 8b4e Sector12 G. Iadarola LHCC#131 - 13th Sep 2017

Arc UFO rate in SB until 31/08/2017 M. Albert TS #1 MD #2 BS heating 16L2 Transf P8 LHCC#131 - 13th Sep 2017

Performance Comparing with 2016 run show a similar slope on the integrated luminosity curve LHCC#131 - 13th Sep 2017

Machine Developments (MD1, MD2) The availability for both blocks reached resp. 85% and 90%. A wide variety of exciting new results “at the forefront of accelerator R&D” was obtained, including: Successful ATS optics measurements and correction at low beta* Validation of the lower impedance of low impedance collimators for HL- LHC Diamond BLM calibration in IR6 The effect of a direct compensation of the beam-beam compensation wire was observed for the first time ADT gain impact on beam quality for high brightness bunches Channeling with crystal goniometers in beam 2 Identification of UFO plane with diamond BLMs Scraping studies in view of addressing the case of a non-working dump Faster ramp by 110 s Instability thresholds with trains revealed unexpected instability in beam 1 horizontal Emittance exchange IR non-linearities studies Aperture measurements at 30 cm Landau damping measurement with BTF Important tests for improving LHC performance LHCC#131 - 13th Sep 2017

BCMS vs 8b4e BCMS: Batch Compression, Merging & Splitting 8 PSB injections  Merging to 4 bunches triple splitting at 2.5 GeV twice double splitting at 26 GeV/c 8/2x3x2x2 = 48 bunches For same LHC bunch intensity PSB bunch intensity and transverse emittance is ~50% of standard scheme 8b4e: 8 bunches & 4 empty buckets (repeatedly) As mitigation scheme for electron cloud in LHC 7 PSB injections  double splitting at 2.5 GeV  twice double splitting at 26 GeV/c 7x2x2x2 = 56 bunches LHCC#131 - 13th Sep 2017