1. Paul Collier & Giulia PapottiX
LHC Performance Workshop Summary Session 5
2016 & Run 2
Paul Collier & Giulia Papotti
March 3rd 2016
Chamonix Session 5 1

2. There is a lot of detail in these talks!!
Session Contents
LHC YETS Recovery
Mirko Pojer
Experiments: Expectations and Requirements
Jamie Boyd
LHC Machine Configuration in the 2016 Proton Run
Roderik Bruce
Beams from the Injectors in 2016
Rende Steerenberg
Plans for the Ion Run in 2016
Reyes Alemany Fernandez
Key Machine Developments for 2016 & Run 2
Rogelio Tomas Garcia
Plans for 2016 and Run 2
Mike Lamont
There is a lot of detail in these talks!!
March 3rd 2016
Chamonix Session 5

3. YETS Recovery It is going to be tight!
Feb. 26/27 – DSO Tests
March, 4 – LHC tunnel closed and start of powering tests
March, 16 – end of powering tests, experiments closed and (official) start of machine check-out
March, 21 – start of beam commissioning
It is going to be tight!
12 Days for Hardware Commissioning
5 Days Machine Checkout
Plans are in place for most systems and services
(LBDS, Kickers, Collimators RF, BI, Controls etc.)
Challenging series of tests – but should be ok.
The big worry is the re-qualification of the cold circuits
March 3rd 2016
Chamonix Session 5

4. Powering Tests Powering tests: Very Challenging!
UPS Tests systematically in each sector
Overhaul of the 32 Main circuit EE systems
HV tests needed afterwards
Temperature drifts in DFB’s and MS
Need for ELQA on many circuits
Powering tests:
7000 tests in 12 days!!
1/3 are 60A … should be ok
Massive parallel testing – rely on automated sign-offs
Very Challenging!
Will rely on availability of the sectors for powering
No access (apart from that needed to power)
March 3rd 2016
Chamonix Session 5

5. Experiment Requests and Requirements
As usual a rich diversity of requests!
High Luminosity Proton-proton running at 13 TeV
Special Runs
Heavy ion Running
Lots of 13 TeV p-p data for ATLAS/CMS 25 ns):
~40cm β* (approximately twice the luminosity/pileup of 2015)
LHCb Leveled with b* = 3m to a m of 1.1
ALICE Leveled with b* = 10m to a m of 0.01
Both require regular flipping of magnet polarity (new for ALICE)
TOTEM aligned from the start and taking data during high intensity runs.
In addition to high intensity p-p must foresee the following:
One early VdM scan (with possibility of another depending on analysis)
A high β* (~2.5km) running period for TOTEM/ALFA (no 90m β* run in 2016)
4 week Heavy Ion period, details still under discussion
LHCf do not foresee taking data in 2016 except in a possible 8 TeV p-Pb run
A few Special Requests
March 3rd 2016
Chamonix Session 5

6. All of these will have some kind of overhead!
Miscellaneous p-p
VdM scans early in the year (~2 days)
hopefully the only one … setup as in 2015:
β* ~ 19 m (IP1 & 5), 24m IP8, ε ~ 3 µm, zero crossing angle (large at IP8) and (βx =βy)
Request also a length scale calibration (same optics as VdM)
LHCb may take SMOG data
Other Things (Special Requests):
CMS interested in a high pile up run (few intense bunches)
ATLAS/CMS want some periods of low/medium pile-up using separation levelling
‘After-glow calibration’ run – 4 widely spaced high intensity bunches
During normal runs:
Experiments support having non-colliding bunches (similar to 2015) as long as these do not cause instabilities
Also request isolated bunches in the filling scheme during ramp-up for ‘out of time’ pile-up studies. Only during occasional fills.
All of these will have some kind of overhead!
March 3rd 2016
Chamonix Session 5

7. Important to minimize the impact on the High-Luminosity running
High Beta* Running
Goal:
Measure elastic proton-proton scattering in the Coulomb-nuclear interference region and potentially measure the luminosity independent of VdM scan.
Beam Settings:
β* as high as possible (β*> 2 km)
Zero crossing-angle
3 bunches (2 colliding in 1&5)
As low emittance as possible
Vertical Roman Pots positioned at 3 σnominal or closer
Scheduling:
Optics commissioned before – extra time added to MD periods for this
1 day final set-up and 3 days Physics probably in September.
Important to minimize the impact on the High-Luminosity running
March 3rd 2016
Chamonix Session 5

8. Requests for Heavy Ion Running
Significantly different requests from the experiments
Still under discussion, Hopefully converge on strategy before the March LHCC
The current options under discussion are:
2016
2018 A
5 TeV
5 TeV B
8 TeV C
It would be useful to know so we can prepare!
Experiments would also like a 5 TeV p-p reference run. But
Differences in opinion as to whether this should be included in the Heavy Ion periods
Long term plan for HI running desirable
March 3rd 2016
Chamonix Session 5

9. Ion Run (from the Machine Side)
The experiments have not made their mind up yet … have to plan for all options
A Pb-Pb run in 2016 would be very similar to 2015
Possibly lower b* but in any case dominated by burn-off
P-Pb is actually slightly easier at higher energy
Smaller frequency difference – orbits less offset.
Can run with the p-p b* for ATLAS and CMS
But ALICE will be limited to higher b* by the 2mm vertical offset and anyway levelled
IP1&5
Ebeam (TeV)
Peak Lumi (cm-2s-1)
Integrated Fill Lumi (ub-1)
Integrated Run Lumi (nb-1)
PbPb
6.37Z
2.7e27 35 1
pPb 4Z
2e29
2600 77
6.5Z
3e29
3900
116
Within the usual 10-15% uncertainty
In all cases Luminosity sharing is going to be a difficult subject
March 3rd 2016
Chamonix Session 5

10. Beams from the Injectors
Injectors running close to the limit(s) – Hence LIU!!
Increasing longitudinal emittance and bunch length will put the PS space charge limit in the shadow of the PSB space charge limit
Same intensity limit (SPS) with slightly smaller transverse emittance might be possible, hence brighter beams
PSB extraction
PS extraction
SPS extraction
Ip / ring
ɛh and ɛv nb
Ip / bunch
[x1011]
[mm ∙ mrad]
batches
bunches
1σ, norm.
LHC25 (STD) initial spec.
13.8
 ≤ 2.5 2
4 + 2
 1.15
 ≤ 3 72
1.15
≤ 3.5
1 – 4 x 72  288
LHC25 (STD) 2015 16
1.9
1.2
2.3
2.5
1 – 2 x 72  144
LHC25 (STD) 2016
16.5
1.3
2.6
LHC25 (STD) Stretched 17
2.4
1.35
LHC25 (BCMS) Operational
7.5
0.8
4 + 4 1 48
1.4
1 – 4 x 48  192
LHC25 (BCMS) Stretched
8.5
0.9
1.1
LHC25 8b4e (STD) 14
~ 1.9
1.7
~2.2
1.6
~ 2.4
LHC50 (STD) 11
1.5
1.8 36
1 - 4 x 36  144
LHC50 (BCMS) 6
1 – 4 x 24  96
March 3rd 2016
Chamonix Session 5

11. Beam Status Still new ideas coming! (80 bunch scheme)
PSB PS
SPS
LHC
25ns/50ns STD
25ns/50ns BCMS
Doublet
100 ns
25ns 8b4e
25ns 80b4e
= Available
= Ongoing / Considered
Still new ideas coming! (80 bunch scheme)
A well scrubbed SPS will be vital to reach top performance
Little room for other improvements until LIU
Availability is the only way to significantly improve overall performance
March 3rd 2016
Chamonix Session 5

12. The time spent doing MD’s invariably pays off
Machine Development
Short Term – of immediate benefit to the performance
As much as possible try to move these into commissioning/operation periods
Medium – development for the future running for run2 & run3
Development of future running scenarios
Long – Necessary MD’s for HL-LHC
‘Long’ is a misnomer. Some of these need answers in the relatively short term, eg to make decisions on the baseline
Very Long – Future machines, basic understanding
For example, studies for FCC
This is not a prioritisation
Data from MD’s of all types is needed to make progress
Balance between long term performance and shorter term gains
MD’s also allow us to develop our basic understanding of accelerator physics
The time spent doing MD’s invariably pays off
March 3rd 2016
Chamonix Session 5

13. MD scheduling A Few Priorities (for the LHC) in 2016:
2016: 22 days Scheduled >30 days requested already!
2017: Shorter year, 15 days scheduled
2018: Hopefully 22 days again
A Few Priorities (for the LHC) in 2016:
ATS Optics for pushed b* and flat beam studies,
Online coupling correction and IR non-linear corrections,
Collective effects: E-Cloud, beam-beam etc. ,
Collimation: Impedance, Quench limits, Halo control, Crystals,
Emittance Growth,
System Development: RF, LBDS, Injection, Beam Instrumentation, Machine Protection,
March 3rd 2016
Chamonix Session 5

14. Machine Configuration for 2016
2015 was a commissioning year ... relaxed b*
emphasis on getting LHC running with 25ns beams at 6.5 TeV
2016 is a production year – push performance … lower b*
Complete intensity ramp up with standard 25ns beams
But we should not jeopardize availability!
For 2016 Choice of b* and associated crossing angle and collimator settings
10 s BB sep
11 s BB sep
Need:
Tighter Hierarchy in IR7/6
10 s beam-beam separation
Optics with re-matched phase
Recover the aperture margin established last year
All depends on the measured aperture being as good as before
March 3rd 2016
Chamonix Session 5

15. Performance Reach
At lower b* the Geometric reduction factor becomes increasingly important
Can reduce the bunch length to limit the effect … to be tested!
Initially start with standard 1.3 ns – look to reduce later
The choice seems to be between b* = 40 and 50 cm
```
Relative Integrated Luminosity
8h fill length
40cm gives slightly more Ldt, but:
Everything is tighter …
will it affect availability? Shorter fills?
On the other hand it did work in tests last year!
Best Plan:
Assume we go for 40cm
Measure aperture for final choice to start with,
Start intensity ramp up,
Be ready to step back if we run into problems (some overhead here)
β* σt
1.3 ns
1.0 ns
50 cm 1
1.1
40 cm
1.08
1.19
20h fill length
β* σt
1.3 ns
1.0 ns
50 cm 1
1.04
40 cm
1.07
1.12
With both 50 and 40 cm it should be possible to reach >1x10+34
March 3rd 2016
Chamonix Session 5

16. P-P Plans for 2016 Keep an eye on UFO’s – adjust BLM’s?
What do we Want:
Stable Safe Operations
Don’t compromise on machine safety!
Don’t do anything to compromise machine reproducibility
Electron Cloud under control
Short dedicated scrubbing
Continue during intensity ramp-up
6.5 TeV, cm b*
Keep an eye on availability
Nominal 25ns beam, 2748 bunches, 288 bpi
May push later to shorter bunches & BCMS
Reasonable Good! Availability
Sustained effort to trace faults
Keep avoidable interruptions to production running to a minimum
Excellent Operational Efficiency
Combined ramp/squeeze
Work on injection process
Keep an eye on UFO’s – adjust BLM’s?
Commission additional interlocks
Special run set-up (VdM & Hi-b*)
Check out ULO
Don’t Forget:
Beware of Earth Faults!
March 3rd 2016
Chamonix Session 5

17. Seems unlikely – Availability is the key to more!
2016 Schedule v1.1
Phase
Days
Initial Commissioning 28
Scrubbing: 4 days initially and then as required 7
Proton physics 25 ns
152
Special physics runs (high b*; VdM) 8
Machine development 22
Technical stops 15
Technical stop recovery 6
Ion setup/proton-lead run
Total
266 days
(38 weeks)
With the present schedule and machine availability we actually spend ~50 days/year in High Intensity p-p stable beams
Can we run Longer?
Seems unlikely – Availability is the key to more!
March 3rd 2016
Chamonix Session 5

18. 2016 Performance Reach 40 cm 50 cm Beam size at IP (um) 14.2 15.9
Somewhat optimistic assumptions based on availability at the end of 2015 and no new issues from lower b*
So, Usual caveats apply:
Availability? Aperture? Interlocks? Phase advance?
ULO, E-Cloud, UFO’s etc. etc.
Assume Nbunch = 2736, 3.5 mm emittance, 1.2z10+11 ppb, 1.25 ns
40 cm
50 cm
Beam size at IP (um)
14.2
15.9
Crossing angle (urad)
185*2
165*2
F (bunch length: 1.25 ns)
0.63
0.72
Peak luminosity (cm-2s-1)
1.1e34
1.0e34
Burn-off lifetime (hour)
25.8
28.5
Integrated per 150 days (fb-1)
33.2
30.7
Reasonable to assume ~25 fb-1 delivered
March 3rd 2016
Chamonix Session 5

19. Run 2 (and Conclusions)
2017 & 2018 slightly longer for p-p operation (+10 days)
Deliver 100+ fb-1 to ATLAS/CMS … keep ALICE, LHCb, TOTEM & ALFA happy
Keep pushing performance and availability
Peak Luminosity limited to ~1.7x10+34 by Inner Triplet cooling
Look forward to HL-LHC without compromising present performance
ATS, b* levelling, LRBB compensation tests, full RF detuning
Prepare for 7 TeV operation
Training campaign in (some) sectors during EYETS?
Enthusiasm and commitment remains high – we could do some serious stuff in 2017 & 2018
M. Lamont
EYETS – Extended Year End Technical Stop – 19 weeks – CMS pixel upgrade
Assume machine stays cold during EYETS
Assume for the moment: p-Pb end 2016, Pb-Pb end 2018 – tbc.
March 3rd 2016
Chamonix Session 5