Theodoros ArgyropoulosBeams Department

Operation Group

On behalf of the LHC team

LHCC 13.09.2017

LHC machine status report

3LHCC#131 - 13th Sep 2017

Outline

LHC Run 2017 Timeline

Scrubbing run

Main achievements

Main operational limitations

Performance

Summary/Next steps

4LHCC#131 - 13th Sep 2017

The LHC schedule (Apr-Sep 2017)

5LHCC#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

6LHCC#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

7LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline1st Stable

Beams

First Stable Beams on Tue 23rd of May Only 25 days after first injection!

• 3b + 3b with intensity ~3x1011 protons per beam

8LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline1st Stable

Beams

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 + commissioningMPS 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, …

Intensity

ramp up

+

Commissio

ning

9LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline1st Stable

Beams

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 + commissioningMPS 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

Sc

rub

bin

gIntensity

ramp up

+

Commissio

ning

10LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline1st Stable

Beams

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

Sc

rub

bin

gIntensity

ramp up

+

Commissio

ning

Physics

Run

11LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline

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

Tech

nic

al

Sto

p1 Physics

Run

12LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline

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

Tech

nic

al

Sto

p1 Physics

RunPhysics

Run

13LHCC#131 - 13th Sep 2017

LHC 2017 Run Timeline

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

Tech

nic

al

Sto

p1 Physics

RunPhysics

Run

14LHCC#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

15LHCC#131 - 13th Sep 2017

Scrubbing run (6-11 June)

• 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

G. Iadarola et al. LMC 04/06/2017

16LHCC#131 - 13th Sep 2017

Main achievements

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

Energy vs β* in IP1/5/8

Fill 5872ATLAS Luminosity

M. Hostettler et al., LMC 28/06/2017

17LHCC#131 - 13th Sep 2017

Main achievements

LQQR

VP

8

2

0

Beam gone..

Minimal change in

power

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

Main operation limitations: Losses@16L2Beam 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 18

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 ~1500bclear intensity dependence

• Change beam type to 8b4e (BCMS before) less e-cloud

activity

LHCC#131 - 13th Sep 2017 19

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

25ns 8b4eG. Iadarola Big

reduction in

the heat

load

LHCC#131 - 13th Sep 2017 20

Main operation limitations: Losses@16L2

25ns 8b4eG. Iadarola Big

reduction in

the heat

load

LHCC#131 - 13th Sep 2017 21

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

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 22

Performance Machine Availability: 79.3 %

Stable beams: 34.6 %

Many faults due to beam loss (16L2)

Fault Duration [h]

Num

ber

of occurr

ences

60 faults due to

Beam Loss

34.6 %

Stable

Beams

1.7%

Precycle

21.7% in fault

(combining

overlapping )

42.0%

Operation

(other)

Data from: https://aft.cern.ch/dashboard

LHCC#131 - 13th Sep 2017 23

Performance

LuminosityRecord 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 24

Performance

LuminosityRecord peak luminosity of

1.74x1034 cm-2s-1 (2556 b)

Peak luminosities around 1.1 x1034 cm-2s-1 per fill with 1916 b of ~1.05x1011 p/bunch

Peak Luminosity zoom

LHCC#131 - 13th Sep 2017 25

8b4e

Performance 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)

J. Wenninger

Tight but

still on

track!

LHCC#131 - 13th Sep 2017 26

SummaryExcellent 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 27

28LHCC#131 - 13th Sep 2017

LHC Schedule

Around 11 weeks remaining

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 29

Thank you for your attention

LHCC#131 - 13th Sep 2017 30

BUCK UP SLIDES

31

32LHCC#131 - 13th Sep 2017

Spikes at 16L2

• 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

8b4e

B. M. Salvachua Ferrando

33LHCC#131 - 13th Sep 2017

E-cloud with 8b4e Sector12

G. Iadarola

34LHCC#131 - 13th Sep 2017

Arc UFO rate in SB until 31/08/2017

M. AlbertTS #1 MD #2 BS heating

16L2Transf

P8

Performance

Comparing with 2016 run show a similar slope on the

integrated luminosity curve

LHCC#131 - 13th Sep 2017 35

36LHCC#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

BCMS vs 8b4e

LHCC#131 - 13th Sep 2017 37

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

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