The "phase 1" of LHC collimation has been fully commissioned, allowing a stored beam energy in the LHC of more than 80 MJ. Its performance has been characterized with beam at 3.5 TeV. This review is considering the present performance, possible limitations in future operation and plans for the upgrade of the system. In particular, it should be reviewed whether the upgrade work in the IR3 dispersion suppressors can be delayed by three years without limiting the LHC performance at 7 TeV.
Review Committee:
Mike Seidel (PSI, chair), Tiziano Camporesi (CERN), Wolfram Fischer (BNL), Brennan Goddard (CERN), Mike Lamont (CERN), Thomas Markiewicz (SLAC), Nikolai Mokhov (FNAL), Andrzej Siemko (CERN), Johannes Wessel (U. Muenster)
Charge:
Review collimation status and upgrade plans. Advise on the following questions:
Are collimation performance and limitations properly analyzed and adequately addressed by upgrade plans?
Can the collimation upgrade in the IR3 dispersion suppressors, presently foreseen for the 2013/4 shutdown, be delayed by three years without limiting LHC performance at 7 TeV?
Have any issues or risks been overlooked that should be addressed in the collimation upgrade plan?
Produce a report, summarizing the recommendations and findings. The committee report is linked as document in the "MATERIAL" section.
Presentations: Overview on collimation system and present resultsSalle Andersson
Salle Andersson
CERN
09:30
Welcome5m
Speaker:
DrRalph Wolfgang Assmann(CERN)
09:35
Introduction to LHC collimation20m
Collimation system description: multi-stage cleaning, different planes, betatron and momentum. Definition of cleaning efficiency. Introduction quench limit. Hierarchy. Limiting physics processes: single-diffractive p scattering, ion fragmentation, ... Comments on hollow e-beam scrapers.
How is it adjusted? How does it perform in LHC (loss maps: measurement and simulation). MD results at 3.5TeV and performance reach at 7TeV. Losses in luminosity production (dispersion suppressors). Measurement protons vs ions. Minimum beam lifetime. First SPS results BPMโs in jaws.
Speaker:
Daniel Wollmann(CERN)
Slides
10:20
Discussion
5m
10:25
Coffee Break
25m
10:50
Radiation to electronics15m
Issues with radiation to electronics in LHC, with focus on collimation insertions. IR7 versus IR3 sensitivity. Benefit of moving losses from IR7 to IR3.
Speaker:
Markus Brugger(CERN)
Slides
11:05
Discussion
5m
11:10
Collimation margins and beta*15m
Stability of LHC machine (orbit, beta). Required margins for collimation setup. Connection collimation to beta*. What beta* can be achieved? Origins of limitations: protection condition, infrequent collimation setups, machine drifts.
Speaker:
Roderik Bruce(CERN)
Slides
11:25
Discussion
5m
11:30
Beam-machine interaction: simulation benchmarking vs first LHC experience15m
FLUKA models and predictions. Comparison between measurements and simulations. Safety margins.
Speaker:
MrAnton Lechner(Atomic Institute of the Austrian Universities, TU Vienna)
Slides
11:45
Discussion
5m
11:50
Collimator design: phase 1 and beyond20m
Short description phase 1 design. Second generation collimators. Improved jaw materials. Collimators for cryogenic regions (warm/cold solution).
Speaker:
Alessandro Dallocchio(CERN)
Slides
12:10
Discussion
5m
12:15
Collimation remote handling10m
Highlights from work for collimation remote handling and remote survey. Plans.
Speaker:
Keith Kershaw(CERN)
Slides
12:25
Discussion
5m
12:30
→
14:00
Lunch
1h 30m
14:00
→
17:40
Presentations: Motivation and plans for collimation upgrade (with ATS management)13/2-005
Outline of collimation upgrade plan. What is planned when and why? What are the questions arising for this upgrade plan?
Speaker:
DrRalph Assmann(CERN)
Slides
14:30
Discussion
5m
14:35
Dispersion-suppressor upgrade IR315m
Foreseen work in IR3 for first long shutdown? Short description. Planning aspects.
Speaker:
Vittorio Parma(CERN)
Slides
14:50
Discussion
5m
14:55
Proton beam performance with and without IR3 upgrade15m
What is lost when not doing the IR3 upgrade? Gain from DS collimators. Performance reach without (see also morning presentation) and with dispersion suppressor collimators for protons.
Speaker:
Adriana Rossi(CERN)
Slides
15:10
Discussion
5m
15:15
Ion beam performance with and without IR3 upgrade15m
Ion performance reach without and with dispersion-suppressor collimators in IR3. Other ion limitations (IR2, ...). Possible impact from delay of IR3 work on IR2 upgrade of dispersion suppressors.
Predicted energy deposition with and without IR3 dispersion suppressor collimators. Gain from collimators. Performance reach from comparing peak heat deposition with quench limit. Comparison with MD results.
Speaker:
DrVittorio Boccone(CERN)
Slides
16:05
Discussion
5m
16:10
Impedance without IR3 upgrade15m
Impedance from tight collimation settings as achieved in MD. Will the beams be stable with impedance, taking into account stabilization from transverse damper and octupoles?
Speaker:
Nicolas Mounet(Ecole Polytechnique Federale de Lausanne (EPFL)-Unknown-Unknown)
Slides
16:25
Discussion
5m
16:30
Outcome Risk Review for IR3 Work20m
Conclusions from May review in EN/TE departments. Technical feasibility? Major risks? Any show-stoppers identified?
Speaker:
Philippe Lebrun(CERN)
Slides
16:50
Discussion
5m
16:55
Activation issues in dispersion suppressors15m
Expected activation levels. Are additional limits expected on work in dispersion suppressors during later shutdowns?
Speaker:
Stefan Roesler(CERN)
Slides
17:10
Discussion
5m
17:15
Radiation damage in dispersion-suppressor magnets15m
Can the radiation dose on unprotected magnets in the dispersion suppressors be accepted? What is the radiation hardness and can unacceptable damage to magnets be excluded, for protons and ions?
