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Concept of a Collimation System with Enhanced Operational Stability and Performance
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 2 Why this talk?
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 3 This Time My Last Collimation Talk? > Thanks to the colleagues, many of them good friends, who worked with me for many years on collimation at CERN. > Thanks to my former students and fellows.
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 4 LHC sytem is published and well documented… Section '8.8 Collimators' of the Chapter ’8 Accelerator Technology’. Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms. Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'.
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 5 7 TeV 50 TeV: EASY?
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 6 7 TeV 50 TeV: EASY? It took us years to solve this for the LHC Difficult!
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 7 R. Assmann Heavily Cooled High-Power LHC collimator Jaw clamping support with cooling Vacuum tank Completed jaw Beam passage for small collimator gap with RF contacts for guiding image currents
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 8 R. Assmann EXAMPLE: Power flow IR3, = 1h, P tot = 90kW Q7LQ7R PRIMSECABS VAC 8%, 7kW Warm Magnets 60%, 54 KW 3%, 2.6 kW7%, 7 kW Side leakage 20%, 19 kW F’wd leakage 1%, 1 kW J.B. Jeanneret, I. Baishev
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 9 The Real Hero of LHC Collimation: TCAPA…
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 10 The Real Hero of LHC Collimation: TCAPA…
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 11 The workhorse LHC collimator…
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 12 The workhorse LHC collimator…
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 13 How will LHC Collimation Behave at High Energy? Quench Limit LHC MagnetsLeakage LHC Collimation 4 TeV 7 TeV 50 TeV 2.0e-4 (1/m) 4.4e-4 (1/m) ≈ 50 – 100 e-4 (1/m) Extrapolation very uncertain, just based on simulations from 1 TeV to 7 TeV!
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 14 WHY? It is the Physics: Comparing MCS and SD processes I ParameterMCSSD Energy E~ 1/E~ ln (E) Length L~ √L~ L MCS brings p from primary to secondary collimator: Imagine going from E0 to E1 in energy. Typical scattering angle: 1 = 0 * E 0 / E 1 Required scattering angle: 1,req = 0,req * √(E 0 / E 1 ) For required scattering angle travel longer length: L 1 = L 0 * √(E 1 / E 0 )
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 15 Comparing MCS and SD processes II Now SD (single diffractive) scattering: Length traversed:L 1 = L 0 * √(E 1 / E 0 ) (from MCS) Cross section: 1 = 0 * ln(0.3*E 1 ) / ln(0.3*E 0 ) Probability for SD scattering with MCS scaling: Effects from SD scattering become stronger with higher beam energy. Loss from 7 TeV to 50 TeV:factor 9.8 √ √
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 16 Situation More Complicated (of course) > Multi-turn behavior not so simple to just linearly add up kicks (as assumed before). > It is not fully correct to express the transport from primary to secondary collimator by a required kick (diffusion process). > Single-diffractive scattering and MCS produce combined effects. > Other processes play into the game. > Still a very useful analytical estimate…
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 17 So for the 50 TeV FCC collider…
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 18 Towards an Optimal 50 TeV FCC Collimation System > Will quickly show the a few concepts without details or any detailed study behind it… Strong warm dogleg bending magnets and a wide tunnel Combined betatron and momentum collimation system Improved phase space coverage by additional primary collimators
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 19 1) Strong warm dogleg bending magnets and wide tunnel
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 20 The dog-leg solution for p and ions… Lower energy particles, e.g. due to single- diffractive scattering Collimators Off-energy dump Intercept 11 MW
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 21 The dog-leg solution for p and ions… Lower energy particles, e.g. due to single- diffractive scattering Collimators Off-energy dump
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 22 2) Combined Betatron and Momentum Cleaning
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 23 LHC Combined Collimation System in IR3 plus two absorbers Vertical Betatron Cleaning Vertical plane performance (shown here) excellent. Horizontal plane performance even better! TCRYO Primary collimator factor 50,000 Nominal goal
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 24 Notes on Combined Betatron/Momentum Collimation
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 25 3) System with Better Operational Robustness ~ 0.6
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 26 Reminder Hierarchy: Primary collimators at 6 Primary collimators Secondary collimators Cold aperture Protection collimators
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 27 Two-Sided Collimators to Constrain Phase Space
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 28 Unavoidable Imperfections Eat Up Margins Limit *
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 29 Solution: Better Phase Space Coverage by Primary Coll. x x’ beam
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 30 Solution 1: Solve Problem Free Orbit Oscillation x x’ beam
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 31 x x’ beam Solution 2: Solve Problem Beta Beat (twice betatron phase advance)
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 32 Triple Primary Collimation – What Does it Mean?
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 33 Beta Beat Impact: Single Primary Collimation Secondary collimator becomes a primary collimator
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 34 Beta Beat Impact: Triple Primary Collimation 45 deg Primary losses always at a primary collimator Primary collimators
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 35 Triple Primary Collimation – Is it really a good idea?
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Ralph Aßmann | FCC Week | 25.3.2015 | Page 36 Outlook
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