LHC Collimation Review 2011

14 Jun 2011, 08:00 → 15 Jun 2011, 18:30 Europe/Zurich

CERN

Mike Seidel (PSI), Ralph Assmann (CERN)

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:

1. Are collimation performance and limitations properly analyzed and adequately addressed by upgrade plans?
2. 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?
3. 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.

document Collimation_2011_summary-V5.pdf

Tuesday 14 June

09:00 → 09:30 Executive session (closed)

09:30 → 12:30 Presentations: Overview on collimation system and present results

09:30 Welcome

Speaker: Dr Ralph Wolfgang Assmann (CERN)

09:35 Introduction to LHC collimation

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.

Speaker: Dr Stefano Redaelli (CERN)

Slides

• SRedaelli_2011-06-14.pdf
• SRedaelli_2011-06-14.ppt
• SRedaelli_2011-06-14slides.pdf

09:55 Discussion

10:00 Collimation setup and performance

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 BPM’s in jaws.

Speaker: Daniel Wollmann (CERN)

Slides 20110614_Review_Collimation_Setup_and_Performance.pptx 20110614_Review_Collimation_Setup_and_Performance.pptx.pdf

10:20 Discussion

10:25 Coffee Break

10:50 Radiation to electronics

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 IR7_status_and_options.pdf IR7_status_and_options.pptx

11:05 Discussion

11:10 Collimation margins and beta*

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 2011.06.14-Collimation_review--Collimation_margins_and_betaStar.pdf 2011.06.14-Collimation_review--Collimation_margins_and_betaStar.pptx

11:25 Discussion

11:30 Beam-machine interaction: simulation benchmarking vs first LHC experience

FLUKA models and predictions. Comparison between measurements and simulations. Safety margins.

Speaker: Mr Anton Lechner (Atomic Institute of the Austrian Universities, TU Vienna)

Slides lhcflukabenchmarks.pdf

11:45 Discussion

11:50 Collimator design: phase 1 and beyond

Short description phase 1 design. Second generation collimators. Improved jaw materials. Collimators for cryogenic regions (warm/cold solution).

Speaker: Alessandro Dallocchio (CERN)

Slides CollimationReviewJune2011_Dallocchio.pdf CollimationReviewJune2011_Dallocchio.pptx

12:10 Discussion

12:15 Collimation remote handling

Highlights from work for collimation remote handling and remote survey. Plans.

Speaker: Keith Kershaw (CERN)

Slides Collimation_remote_handling_14_June_2011_reviewb.pdf Collimation_remote_handling_14_June_2011_reviewb.pptx

12:25 Discussion

12:30 → 14:00 Lunch

14:00 → 17:40 Presentations: Motivation and plans for collimation upgrade (with ATS management)

14:00 Expectations from Review

Speaker: Steve Myers (CERN)

14:05 Collimation project upgrade plan and questions

Outline of collimation upgrade plan. What is planned when and why? What are the questions arising for this upgrade plan?

Speaker: Dr Ralph Assmann (CERN)

Slides 2011-06-14_collreview_assmann_out2.pptx

14:30 Discussion

14:35 Dispersion-suppressor upgrade IR3

Foreseen work in IR3 for first long shutdown? Short description. Planning aspects.

Speaker: Vittorio Parma (CERN)

Slides DS_collimator_project.pdf DS_collimator_project.pptx

14:50 Discussion

14:55 Proton beam performance with and without IR3 upgrade

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 20110614_CollimationUpgradeReview_AR.pdf 20110614_CollimationUpgradeReview_AR.pptx

15:10 Discussion

15:15 Ion beam performance with and without IR3 upgrade

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.

Speaker: Giulia Bellodi (CERN)

Slides

• 2011review_final.pdf
• 2011review_final.pdf
• 2011review_final.pptx

15:30 Coffee Break

15:50 Energy deposition with and without IR3 upgrade

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: Dr Vittorio Boccone (CERN)

Slides DSReview11_Boccone_Final.pdf DSReview11_Boccone_Final.pptx

16:05 Discussion

16:10 Impedance without IR3 upgrade

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 impedance_coll_review_14062011.pdf

16:25 Discussion

16:30 Outcome Risk Review for IR3 Work

Conclusions from May review in EN/TE departments. Technical feasibility? Major risks? Any show-stoppers identified?

Speaker: Philippe Lebrun (CERN)

Slides Review_of_the_cryogenic_by-pass_for_the_LHC_DS_collimators.pdf Review_of_the_cryogenic_by-pass_for_the_LHC_DS_collimators.ppt

16:50 Discussion

16:55 Activation issues in dispersion suppressors

Expected activation levels. Are additional limits expected on work in dispersion suppressors during later shutdowns?

Speaker: Stefan Roesler (CERN)

Slides CollReview0611-RP1.pdf CollReview0611-RP1.ppt

17:10 Discussion

17:15 Radiation damage in dispersion-suppressor magnets

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?

Speaker: Dr Davide Tommasini (CERN)

Slides CR-Davide.pdf CR-Davide.pptx

17:30 Discussion

17:40 → 17:50 Break

17:50 → 18:50 Executive session (closed)

20:00 → 22:00 Review Dinner

Wednesday 15 June

09:00 → 10:30 Discussion of review committee with ATS and project management (closed)

slides 2011-06-15_collreview_assmann_input.pdf 2011-06-15_collreview_assmann_input.pptx

10:30 → 12:30 Review committee followup and discussions

slides QLevels20110615.pdf

12:30 → 14:00 Lunch

14:00 → 17:00 Review committee followup and discussions

17:00 → 18:30 Summary and conclusion (with ATS management)

slides committee_report.pdf committee_report.pptx