20 th US-LARP Collaboration Meeting - CM20 April 8 th -10 th , 2013 Embassy Suites - Napa Valley, CA, USA LHC Collimation Project Status Stefano Redaelli, CERN, BE-ABP for the Collimation Project and HL-LHC-WP5 teams The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Introduction Baseline collimation upgrade strategy for LS1 defined in 2011 - Decided to postpone major changes in the dispersion suppressors (DSs) - Other important upgrades will take place in LS1: Collimators with BPM design The good performance at 4 TeV (up to 140 MJ!) confirmed this strategy, but uncertainties remain for the extrapolations to 7 TeV - Need to review cleaning, lifetime assumptions, quench limits, impedance... The possible needs for local collimation in the dispersion suppressor have steered the development of the 11 T dipoles - Important progress - see magnet talks. Can we get them in LS2 if needed? - What do we need to decide now to be ready to take a decision in 2015? External collimation review is being organized: 30-31/05/2013 - Scope: present the baseline on collimation upgrades on mid and long term: (1) Full beam intensity and luminosity; (2) x2 design; (3) HL-LHC. - Mandate: advice on 11 T dipole strategy until post-LS1 operation, for actions in LS2. Other important studies for collimation upgrades are ongoing, within and outside CERN, to ensure readiness for HL-LHC era! S. Redaelli, US-LARP CM20 08/04/2013 2
Outline Introduction Collimation up to 140 MJ News on upgrade studies Conclusions S. Redaelli, US-LARP CM20 08/04/2013 3
(Some) collimation people S. Redaelli, US-LARP CM20 08/04/2013 4
Contributions for this talk B. Salvachua (2012-13 performance) R. Bruce (post-LS1 performance) G. Stancari, A. Valishev, W. Fisher (hollow e-lens) N. Simos, A. Bertarelli, N. Mariani, L. Lari (BNL radiation tests) A. Bertarelli et al. (collimator material studies) M. Sapinski (non-collimation quench tests) W. Scandale, D. Mirarchi (crystal studies) O. Bruning, L. Rossi, H. Schmickler (overall strategy within HL-LHC) Core collimation team in the LHC accelerator physics group: R. Bruce, M. Cauchi, D. Deboy, L. Lari, D. Mirarchi, E. Quaranta, M. Salvachua, A. Rossi, A. Marsili, G. Valentino. Members who left recently: R. Assmann, D. Wollmann. Acknowledgements: OP team, ADT team and many others. S. Redaelli, US-LARP CM20 08/04/2013 5
Collimation cleaning at 4 TeV ( β * =60cm) Betatron Beam 1 Cleaning BLM i defined Cleaning inefficiency [BLM/BLM tcp ] BLM tcp here as: Dump Off-momentum TCTs TCTs 0.00001 1/10000 TCTs TCTs 0.000001 B. Salvachua 2012-13: “tight” collimator settings (TCP gaps as at 7 TeV!) for higher β * : Highest COLD loss location: efficiency of > 99.99% ! 60 cm for protons, 80cm for ions. Most of the ring actually > 99.999% S. Redaelli, US-LARP CM20 08/04/2013 6
How “tight” tight settings are? 7 2011 6 ± 1.5 mm from 5 the 110 MJ beam (3.5TeV)! 4 N 3 2 1 0 0 2 4 6 8 Collimator full gap [ mm ] 25 2012 20 ±1.05 mm from the 140 MJ 15 beam (4 TeV)! N 10 5 0 0 2 4 6 8 Collimator full gap [ mm ] “Tight” collimator settings in the betatron cleaning (IR7): - Primary collimator gaps are the nominal as at 7 TeV! - Secondary collimator retracted by 2 sigmas ( σ 4TeV ). - Tertiary collimators at 9 sigma for a β * of 60 cm! S. Redaelli, US-LARP CM20 08/04/2013 7
Loss maps in IR7 Beam 1 1/10000 B. Salvachua Critical locations (both beams): losses in the dispersion suppressor magnets Q7-Q11, from single diffractive interactions at the primary collimators. S. Redaelli, US-LARP CM20 08/04/2013 8
Stability of cleaning in 2010-12 2010-2012 Collimation Cleaning Performance Plotted: cleaning at the worse cold location versus time -3 10 Cleaning inefficiency B1 HOR B1 VER B2 HOR B2 VER -4 10 3.5 TeV, “relaxed” 3.5 TeV, “relaxed” nominal settings MD nominal settings MD 4 TeV, “tight” 2010 tight settings MD 2011 2012 -5 10 18/06/10 28/07/10 11/08/10 27/08/10 04/10/10 18/10/10 11/03/11 04/04/11 12/04/11 MD nominal MD tight 15/05/11 24/06/11 13/07/11 05/09/11 22/10/11 29/03/12 31/03/12 02/04/12 30/04/12 30/04/12 MD nominal MD nominal RC 01/07/12 01/07/12 01/07/12 11/07/12 16/07/12 16/07/12 16/07/12 23/11/12 23/11/12 B. Salvachua 20 Excellent stability of cleaning Setup time per performance observed! Setup Time per Collimator [min] collimator (2010-2012) 15 Achieved with only 1 alignment per year in IR3/6/7 (2x30 collimators). 10 New alignments are only repeated 5 for new physics configurations (it remains crucial to be efficient!) 0 MAY 2010 MAR 2011 MAR 2012 MAY 2012 MD OCT 2012 MD Collimator Alignments S. Redaelli, US-LARP CM20 08/04/2013 9
Stability of cleaning in 2010-12 2010-2012 Collimation Cleaning Performance Plotted: cleaning at the worse cold location versus time -3 10 Cleaning inefficiency B1 HOR B1 VER B2 HOR B2 VER -4 10 3.5 TeV, “relaxed” 3.5 TeV, “relaxed” nominal settings MD nominal settings MD 4 TeV, “tight” 2010 tight settings MD 2011 2012 -5 10 18/06/10 28/07/10 11/08/10 27/08/10 04/10/10 18/10/10 11/03/11 04/04/11 12/04/11 MD nominal MD tight 15/05/11 24/06/11 13/07/11 05/09/11 22/10/11 29/03/12 31/03/12 02/04/12 30/04/12 30/04/12 MD nominal MD nominal RC 01/07/12 01/07/12 01/07/12 11/07/12 16/07/12 16/07/12 16/07/12 23/11/12 23/11/12 B. Salvachua 20 Excellent stability of cleaning Setup time per performance observed! Setup Time per Collimator [min] collimator (2010-2012) 15 Collimation cleaning not enough to Achieved with only 1 alignment per define the LHC performance : year in IR3/6/7 (2x30 collimators). beam lifetime and quench limits 10 at 7 TeV must be considered. New alignments are only repeated 5 for new physics configurations (it remains crucial to be efficient!) 0 MAY 2010 MAR 2011 MAR 2012 MAY 2012 MD OCT 2012 MD Collimator Alignments S. Redaelli, US-LARP CM20 08/04/2013 10
LHC quench tests with beam Recap. on the LHC beam loss monitoring system: - Beam losses are monitored over 12 “running sums” (RS), from 40 μ s (1/2 turn) to 80s. - Independent thresholds for each RS to protect the machine from ultra-fast to steady-state losses. Five quench tests were proposed at the end of the 2012-13 run to probe different time scales: � - Collimator test with protons � - Collimator test with ions (not done due to unavailability of ion beams) � - Orbital bumps � - Fast losses on UFO range Steady-state dispersion � - Single-pass with injected beam suppressor with ions ( not done! ) Steady-state Truly impressive amount dispersion suppressor of work done by MANY with protons teams involved. Steady-state Dedicate WG started to with orbital consistently address all bump 20 mW/cc the experimental results. UFO-timescale losses ns-losses for Ebeam>4 TeV (async.beam dump) 6 TeV M. Sapinski for the Quench Strategy Working Group S. Redaelli, US-LARP CM20 08/04/2013 11
Collimator proton quench tests Losses Fill_3569 B1_B2 4000GeV 2013-02-15 03:15:03 Preliminary analysis of beam tests done on 14/02/2013 2 10 cold 1.06 MW 10 collimator on TCP ʼ s warm 1 BLM signal [Gy/s] -1 10 1 kW at Q8 Achieved by -2 10 blowing up the beam with -3 10 damper excitation -4 10 -5 10 -6 10 B. Salvachua -7 10 19400 19600 19800 20000 20200 20400 20600 s [m] Controlled beam excitation over several seconds: Peak losses > 1MW on TCP! Worsened cleaning by relaxing collimator settings (“very relaxed”). Achieved 2 to 5 times the assumed quench limit at 4.0 TeV without quenching ! (2011: only achieved ~65% of 3.5 TeV limit.) S. Redaelli, US-LARP CM20 08/04/2013 12
Collimator proton quench tests Losses Fill_3569 B1_B2 4000GeV 2013-02-15 03:15:03 Preliminary analysis of beam tests done on 14/02/2013 2 10 cold 1.06 MW 10 collimator on TCP ʼ s warm 1 BLM signal [Gy/s] -1 10 1 kW at Q8 Achieved by -2 10 blowing up the beam with -3 10 damper excitation -4 10 -5 10 -6 10 B. Salvachua -7 10 19400 19600 19800 20000 20200 20400 20600 s [m] Controlled beam excitation over several seconds: Peak losses > 1MW on TCP! Worsened cleaning by relaxing collimator settings (“very relaxed”). Achieved 2 to 5 times the assumed quench limit at 4.0 TeV without quenching ! (2011: only achieved ~65% of 3.5 TeV limit.) S. Redaelli, US-LARP CM20 08/04/2013 13
Achieved losses vs quench limit 2012 New method to excite controlled (4 TeV) blow-up with the transverse damper (ADT): could probes “steady” losses between 1.3s and 5.2s! Achieved loss rate a factor 2-5 larger 2011 than the assumed quench limits! (3.5TeV) Remark: We have seen this type of losses during 2012! Collimator BLMs are set to B. Salvachua dump beams in case of losses > 200kW)! RS09 = 1.3 s 1.3 s RS10 = 5.2 s 5.2 s Ratio BLM Ratio BLM BLM Assumed BLM Assumed Ramp 3: ~1MW to to Measurement Quench Limit Measurement Quench Limit Quench Quench [Gy/] [Gy/s] [Gy/] [Gy/s] Limit Limit BLMQI.08L7.B2I10_MQ 1.08E-02 4.65E-03 2.3 8.42E-03 1.67E-03 5.1 BLMQI.08L7.B2I20_MQ 3.81E-03 6.40E-03 0.6 2.87E-03 2.29E-03 1.3 S. Redaelli, US-LARP CM20 08/04/2013 14
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