Preparation of Review

Preparation of Review R. Assmannet al CWG, 6.6.2011 CWG 6.6.2011

Review Committee DRAFT Chair: Mike Seidel (PSI) Committee: T. Camporesi (CERN) W. Fischer (BNL) M. Lamont (CERN) T. Markiewicz (SLAC) N. Mokhov (FNAL) A. Siemko (CERN) B. Goddard(CERN) J. Wessel (U. Muenster) CWG 6.6.2011

Talks: Introduction Session DRAFT S. Redaelli Collimation system description (incl. comments on hollow e-beam scrapers) A. Dallocchio Collimator design, Phase 1 and beyond (incl. advanced materials), designs for warm and cold places D. Wollmann Collimation setup and performance, (incl. BPM’s in jaws), mention ions EN/STI Energy deposition (General) R. Bruce Collimation margins and beta* EN/HE Remote handling CWG 6.6.2011

Mandate Can the dispersion-suppressor upgrade work in IR3 be delayed without limiting the LHC performance from collimation? CWG 6.6.2011

Talks: Upgrade Session (160min) DRAFT S. Myers Expectations from review R. Assmann Collimation upgrade plan O. AberleIR3 warm upgrade V. Parma DS upgrade P. Lebrun Outcome Risk Review all below 10min A. Rossi P-beam performance with/wo DS collimators JJ/GB Ion performance with/wo DS collimators EN/STI Energy deposition with/wo DS collimators N. Mounet Impedance wo DS collimators D. TommasiniRadiation damage to SC magnets M. Brugger R2E issues in IR7 S. Roesler Activation issues: Upgrades until when? CWG 6.6.2011

Review https://indico.cern.ch/event/collreview2011 CWG 6.6.2011

DRAFT Present Analysis Collimation Sufficient data with the LHC beams has been recorded and the requested beam tests for LHC collimation have been performed. The results allow an update of the LHC performance reach calculation. This calculation is still affected by uncertainties but for the first time provides reasonable certainty for being used as a basis for decisions. A 8-point plan for LHC collimation is proposed, including important adjustments in the foreseen work. Based on present best knowledge and understanding, this 8-point plan is compatible with nominal LHC performance at 7 TeV in 2014 and ultimate LHC performance in 2017. At the same time the workload is reduced (e.g. no IR3 upgrade of dispersion suppressors in 2013) and collimation work is reoriented at the directions that are most efficient for optimizing LHC performance. It is noted that a small performance risk for the LHC cannot be fully excluded. However, this risk is deemed acceptable. Lower risks can only be achieved by upgrading the LHC dispersion suppressors as soon as possible, i.e. IR3 during the first long shutdown. CWG 6.6.2011

DRAFT 8 Point Plan: 1 – 2 • Action: Cancel the collimation upgrade for the IR3 dispersion suppressors during the first long shutdown in 2014. Complete ongoing prototyping work.Justification: Within reasonable uncertainties it is expected that nominal LHC luminosity can be reached without this work. This conclusion is based on the new results from the May 2011 machine studies.Note: In case of moving betatron cleaning to IR3, DS collimators might again become needed. Clarify until mid-June. • Action:Prepare the collimators required for temporary installation of vertical collimators into IR3.Justification:At the moment it cannot be guaranteed that nominal intensity can be reached in IR7. Important intensity limits can occur due to R2E. A combined betatron/momentum collimation system in IR3 is an inexpensive and effective solution with little impact on other shutdown activities. CWG 6.6.2011

8Point Plan: 3 – 5 DRAFT • Action: Start an overall study for the upgrade of the LHC DS’s with collimators in IR1/2/3/5/7, developing a coherent approach. Develop and prototype adequate collimator hardware for readiness in 2016, in close contact with GSI.Justification: The urgency in IR3/7 DS’s is lower than anticipated and upgrades of other DS’s might become more urgent. • Action:Continue full speed the work towards second generation collimators with beam position buttons in their jaws, aiming for first installations in 2014.Justification: Overcome the limitations in collimator setup. Allow for best efficiency and small b* at 7 TeV. Avoid lengthy collimator setup periods and win in integrated luminosity. • Action:Continue the work towards second generation collimators with robust collimator materials or damage handling concepts, with EuCARD+ LARP collaborators. Readiness goal is 2016.Justification: Prepare for LHC beams with higher than ultimate brightness. CWG 6.6.2011

DRAFT 8Point Plan: 6 – 8 • Action: Accelerate work on radiation measures with first installations in 2013 and readiness for 2016.Justification: The success of the LHC leads to a faster intensity ramp up and activation of collimators. • Action: Start work on design and development of hollow e-beam scrapers for the LHC. Readiness goal is 2016.Justification: Hollow e-beam scrapers are an inexpensive and safe way to reduce the magnitudes of peak beam loss. Provides insurance against risks taken in action 1, in particular against possible surprises when going from 3.5 TeV to 7 TeV. • Action: Assign additional dedicated CERN staff resources to the setup and optimization of the existing collimation system. Justification: Not implementing the IR3 upgrade in the DS’s implies that the associated efficiency gain of a factor 10-30 will not come. The existing system must then be operated much longer than foreseen, at the limits of its capabilities. This imposes heavy additional workload for manual setup and optimization. CWG 6.6.2011

Other Work DRAFT • It is noted that the eight points proposed do not describe the full collimation work plan. Additional work packages exist on various topics: • collimation setup in the control room • modeling of performance • optimization of setup accuracy and speed • various small collimation upgrades (e.g. IR2) • IR upgrades within HL-LHC design study • These work packages are not affected by the proposed changes in work plan and it is assumed that they are continued as planned. CWG 6.6.2011

Comments please… CWG 6.6.2011

Preparation of Review