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

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

4. The LHC schedule (Apr-Sep 2017)
LHCC# th Sep 2017

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

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

7. 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# th Sep 2017

8. 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# th Sep 2017

9. 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# th Sep 2017

10. 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 ms risetime) correlated by losses in cell 16L2
LHCC# th Sep 2017

11. 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# th Sep 2017

12. 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# th Sep 2017

13. 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 p/bunch on average promising for the rest of the run
LHCC# th Sep 2017

14. 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# th Sep 2017

15. 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 and actions taken during EYETS clearly beneficial
LHCC# th Sep 2017

16. 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, h, h
150  140  130  120 μrad
Fill 5872
ATLAS Luminosity
M. Hostettler et al., LMC 28/06/2017
LHCC# th Sep 2017

17. 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# th Sep 2017

18. 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# th Sep 2017

19. 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# th Sep 2017

20. 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# th Sep 2017

21. 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# th Sep 2017

22. 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# th Sep 2017

23. 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:
LHCC# th Sep 2017

24. 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# th Sep 2017

25. 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# th Sep 2017

26. 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 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# th Sep 2017

27. 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# th Sep 2017

28. LHC Schedule
Around 11 weeks remaining
LHCC# th Sep 2017

29. 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# th Sep 2017

30. Thank you for your attention
LHCC# th Sep 2017

31. BUCK UP SLIDES

32. 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# th Sep 2017

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

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

35. Performance
Comparing with 2016 run show a similar slope on the integrated luminosity curve
LHCC# th Sep 2017

36. 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# th Sep 2017

37. 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# th Sep 2017