CERN Phase II Collimation Conceptual Review Summary 09 April 2009 LARP CM12 Napa, CA Tom Markiewicz/SLAC BNL - FNAL- LBNL - SLAC US LHC Accelerator Research Program

LARP CM April 2009Collimation Conceptual Review Summary - T. MarkiewiczSlide n° 2 / 14 Collimation News from LHC “Cryo Collimators” proposed to bring LHC to ultimate luminosity: Conceptual Design Review 2-3 APR 2009 supports “continued engineering study” The yet undesigned “Cryo Collimators” are modeled as warm 1m Tungsten adjustable jaws set at ~15  in the cold part of the ring on either side of the IR7 betatron collimation system By protecting cold dipoles in the “dispersion suppressor” from “single diffractive protons” produced in primaries that miss all secondary collimators intensity limit in LHC improved by > x15-90 Growing belief that transverse feedback will control impedance limit to LHC intensity and that this FB is aided in the low frequency region of interest by materials such as ceramics that lower the real part of the impedance and are robust CERN Phase II secondary design is an improved version of Phase I with “cartridge” zone for placement of jaw material. TT60 “High Radiation Material” test area a prerequisite to a material downselect. –Construction of TT60 supported by review committee Desire for immediate development of electron lens with hollow e-beam profile for use as scraper

RWA, LHCC 11/08 -3 m shifted in s halo Halo Loss Map Upgrade Scenario +3 m shifted in s Downstream of IR7  -cleaning transversely shifted by 3 cm cryo-collimators NEW concept Losses of off-momentum protons from single-diffractive scattering in TCP without new magnets and civil engineering See talk J. Jowett

RWA, LHCC 11/08R. Assmann, CERN 4 quench level Proton losses phase II: Zoom into DS downstream of IR7 Impact pattern on cryogenic collimator 1 Impact pattern on cryogenic collimator 2 T. Weiler Very low load on SC magnets  less radiation damage, much longer lifetime %/m  %/m See talk T. Weiler Cryo-collimators can be one-sided!

A. Bertarelli – A. DallocchioLHC Collimation Phase II – Design Meeting – 19/09/2008 RWA, LHCC 11/08R. Assmann, CERN BPM integration Integration of BPMs into the jaw assembly gives a clear advantage for set-up time  Prototyping started at CERN BPM pick-ups BPM cables and electrical connections R. Assmann, CERN

RWA, LHCC 11/08R. Assmann, CERN 6 Location of HiRadMat 3 TT60 from SPS TI 2 to LHC 3 possible locations of HiRadMat: former West Area Neutrino Facility TT61 tunnel former T1 target area C. Hessler R. Assmann, CERN

RWA, LHCC 11/08R. Assmann, CERN 7 The Tevatron e-Beam Lens R. Assmann, CERN See talk J. Smith.

RWA, LHCC 11/08R. Assmann, CERN 8 Suggested Milestones I 2009 Review conceptual design, go ahead, refined WP’s. Start WP’s cryogenic collimation and hollow e-beam lens. Continue other WP’s. 2010SPS: Beam test of collimator with in-jaw pick-ups (presently under construction), if we can install. Study results on in-jaw pick-up with Darmstadt/TEMF. LHC: Review beam experience with phase I collimation system. 2010/11TT60: HiRadMat test facility installation. 2011WP cryogenic collimation completed and hardware constructed. HiRadMat: Beam tests of advanced secondary collimators. HiRadMat: Material tests with beam shock impact. SPS: Beam tests of the hollow e-beam lens scraping. 2011/12LHC: Modify SC dispersion suppressors around IR7 and IR3. LHC: Install collimators into the space created. R. Assmann, CERN

RWA, LHCC 11/08R. Assmann, CERN 9 Suggested Milestones II 2012:LHC: Ready for nominal intensity. LHC: Parasitic beam tests of advanced secondary collimators. LHC: Parasitic tests of the hollow e-beam lens. Construction decision for phase II secondary collimators, decision for materials and concept (taking into account LHC beam experience, e.g. frequency of erroneous beam hits). 2013LHC: Reduced beam tails and lower peak loss rate with scraping. Construction of phase II secondary collimators. 2013/14LHC: Installation of advanced secondary collimators. 2014LHC: Collimation with ultra-high efficiency, fast and non- destructive collimator setup and safe halo scraping. R. Assmann, CERN

RWA, LHCC 11/08R. Assmann, CERN 10 Schedule for Discussion (ambitious and result-oriented “wish” schedule) YearMilestone 2009 Conceptual solution presented. Start/continuation of serious technical design work on all work packages (delays will shift all future milestones) Review of lessons with LHC beam. Technical design review. SPS test of CERN prototype with integrated BPMs. 2011HiRadMat test facility completed and operational Cryogenic collimation installed and operational  nominal intensity in reach. Production decision for phase II secondary collimators. 2013Hollow e-beam lens operational for LHC scraping. 2014Phase II completed with installation of advanced secondary collimators  Ready for nominal & ultimate intensities.

CHARGE to committee: Review the conceptual solution of LHC collimation (phase II) for nominal/ultimate beam intensities. Assess the urgency for phase II of LHC collimation. Committee recommends a staged approach to the overall upgrade the collimation system Work Package A (Dispersion Suppressor Collimators): Committee recommends to continue immediately with engineering design; prefer warm solution; Pro: seems a practicable solution (no show stoppers seen); activation in disp. suppressor section will rise with time; heat load in cold magnets/cryo system is fundamental problem; helps ion problems; unlikely that it will not be useful Con: relatively large effort required; unexpected new experiences from phase 1 operation might require other improvements;

CHARGE to committee: Assess if all expected collimation problems or solutions have been adequately addressed, including needs for the experiments. clarify the time scale of possible performance degradation of the presently installed graphite collimators (data from Kurchatov Inst.) better exploration of implications of activation in IR7 needed (may affect installation of cryo collimators) study if fixed collimators in dispersion suppressor are feasible; this would simplify technical solution clarify whether flexibility of beam optics in dispersion suppressor section is compromised by planned modifications study advanced secondary collimator scheme with imperfections (beam optics, collimator alignment etc.) understand the importance of irradiation test facility; we were not presented with a plan detailing the experiments, diagnostics and the uniqueness of this facility; positive experience with phase-I jaw tests is acknowledged

13 Continued: spikes of loss rate are potentially very important; relying only on the hollow e- beam scraper is risky (beam core blowup; non-uniformity of hollow beam); committee recommends to also explore alternative schemes integrated BPM`s are excellent idea; study impact of showers on integrated BPM possibly weak point: detection of damage at primary collimators (observe degradation of cleaning efficiency but do not know origin; temperature measurement may not be conclusive) study implementation of thin scattering tip at edge of primary collimators; increases local diffusion rate → larger impact parameter; might help collimation of heavy ions HERA experience: dust falls into beam, causes extreme bursts of losses; e.g. from vertically movable Roman pots experimental tests using SPS etc. are encouraged

LARP CM April 2009Collimation Conceptual Review Summary - T. MarkiewiczSlide n° 14 / 14 RC 5 Year Plan: For Discussion