FCC hh Daniel Schulte FCC kickoff meeting February
FCC – hh Daniel Schulte FCC kick-off meeting – February 2014
FCC-hh Study Scope 2014 Q 1 Q 2 Q 3 2015 Q 4 Q 1 Q 2 Q 3 2016 Q 4 Q 1 Q 2 Q 3 2017 Q 4 Q 1 Q 2 Q 3 2018 Q 4 Q 1 Q 2 Q 3 Q 4 Study plan, scope definition Explore options “weak interaction” Workshop & Review: identification of baseline conceptual study of baseline “strong interact. ” Workshop & Review, cost model, Form teams LHC results study re-scoping? Identify design drivers and address them Elaboration, Collect critical R&D items and start prioritisation consolidation Workshop & Review Started with a tentative parameter document Report Started with critical issues and design drivers contents of CDR Release CDR FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 2
Rational for Parameter Choice • Put together something that is reasonable • Somewhat conservative • With some aggressive choices to avoid excessive cost • To criticise and improve • To guide the design work and identify challenges • Seed of the baseline • More aggressive choices will be considered as alternatives • When more R&D is required • When they involve a performance/cost trade-off • http: //indico. cern. ch/event/282344/material/3/ Authors: A. Ball, M. Benedikt, L. Bottura, O. Dominguez, F. Gianotti, B. Goddard, P. Lebrun, M. Mangano, D. Schulte, E. Shaposhnikova, R. Tomas, F. Zimmermann FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 3
Physics Parameters LHC Cms energy [Te. V] Luminosity [1034 cm-2 s-1] Cms energy 14 1 Bunch distance [ns] Luminosity HL-LHC 5 HE-LHC FCC-hh 33 100 5 5 25 25 (5) Background events/bx 27 135 147 170 (34) Bunch length [cm] 7. 5 8 • Two main experiments sharing the beam-beam tuneshift • Two reserve experimental areas not contributing to tuneshift • Currently assume 25 ns as baseline • May be able to reduce bunch spacing and background Might be able to increase bunch length • Will explore this if experiments find it useful • • 80% of circumference filled with bunches FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 4
Basic Machine Parameters LHC HE-LHC FCC-hh 8. 33 20 16 (20) Magn. Aperture [mm] 56 40 40 Arc fill factor [%] 79 79 79 Dipole field [T] HL-LHC Straight section 8 x 0. 5 km 16. 8 km Total length 26. 7 km 100(83)km • Need to determine overall layout • LHC-type with 12 insertions (1. 4 km average, pairwise same length) • Racetrack-type with two almost straight sections (each 8. 4 km) • • Fill factors include dispersion suppressors (80. 5% in the cell) Ambitious magnet strength goal 16 T (Ni 3 Sn) or 20 T (with high temperature superconductor) FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 5
Beam Parameters LHC HL-LHC HE-LHC FCC-hh Bunch charge [1011] 1. 15 2. 2 1 1 (0. 2) Norm. emitt. [mm] 3. 75 2. 5 1. 38 2. 2(0. 44) IP beta-function [m] 0. 55 0. 15 0. 35 1. 1 IP beam size [mm] 16. 7 7. 1 5. 2 6. 8 (3) RMS bunch length [cm] 7. 55 8 • • Values in brackets for 5 ns spacing Same values for 16 T and 20 T design • • Beam-beam tuneshift for two IP 0. 01 Beta-function at IP scaled with sqrt(E) from one LHC insertion line design with 0. 4 m (some safety margin) Ø Beam current Ø Bunch charge Ø Emittance as function of bunch charge FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 6
Synchrotron Radiation LHC HL-LHC HE-LHC FCC-hh Dipole field [T] 8. 33 20 16 (20) Synchr. Rad. in arcs [W/m/aperture] 0. 17 0. 33 4. 35 28 (44) Eng. Loss p. turn [Me. V] 0. 007 0. 2 4. 6 (5. 9) Crit. eng. [ke. V] 0. 044 0. 575 4. 3 (5. 5) 0. 2 4. 8 (5. 8) Total synr. Power [MW] 0. 0072 0. 0146 Long. Damp. Time [h] 12. 9 1. 0 0. 54 (0. 32) Transv. Damp. Time [h] 25. 8 2. 0 1. 08 (0. 64) • Values in brackets for 20 T magnet field • • • Radiation given by beam energy and dipole field Leads to damping of the longitudinal and transverse emittance Leads to significant power load on the beam screen FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 7
Operation FCC-hh Turn-around time [h] 19. 1 (15. 9) 5 Optimum run time [h] 12. 1 (10. 7) Luminosity lifetime [h] Int. lumi / day [fb-1] 2. 2 (2. 1) • Values in brackets for 20 T magnet field • • Beam lifetime due to burn-off considered Assume to keep transverse emittance proportional to charge Assume longitudinal emittance is kept constant Average luminosity is about 50% of maximum FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 8
Examples of Identified Work and Challenges • List is by far not complete • I do not have the time to present even what we know • Need to review all the different areas • Please help with expertise and experience FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 9
Layout • Arc design • Magnet performance dependent • One of the main parameter drivers • Layout of insertion lines • Experiment insertions • Collimation • Injection and extraction • Others (RF, additional experiments) • Geometry • Racetrack vs. LHC-type layout • In the first stage, need to determine required lengths for beam lines and identify and address the main issues FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 10
Magnets • Dipoles are critical for FCC-hh design and cost • Achievable dipole field See talk of B. Strauss Many talks in breakout session • Cost as a function of aperture (and field) • Strong cost increase with increasing aperture • Practical minimum aperture is likely 40 mm (L. Bottura) • Use this as an ambitious target • Tolerances and field quality important for the beam and cost • Dynamic aperture, alignment, … • Magnet swing is critical for injection • Range, assume factor 16 for now • Tolerances and field quality, will need to be studied • Speed • Other magnets are also design drivers (e. g. insertion magnets) FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 11
Arc Design and Beam Pipe • Goal is to see if we can stay at 40 mm aperture for magnets • Tentative scaling from LHC to 200 m-long FODO cells • Currently consider four beam pipe design approaches • LHC-type copper coated beam screen (discussed here) • LHC-type beam screen coated with high temperature superconductor • Use of photon stops • Open midplane magnets FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 12
LHC-Type Design Current goal • beam aperture: 2 x 13 mm • High impedance • magnet aperture: 2 x 20 mm • Space for shielding: 7 mm Synchrotron radiation in arcs • 28 W/m/beam for 16 T • 44 W/m/beam for 20 T • Total 4. 8 -5. 8 MW Most of the power will be cooled at the beam screen, i. e. at its temperature A part is going into the magnets, i. e. cooled at 24 K FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 13
Power for Cooling Can only use some temperatures in order to maintain good vacuum Ph. Lebrun <20, 40 K-60 K, 100 K-120 K, >190 K But at 100 K the impdance is about twice as hight as at 50 K Choose 50 K Need 100 MW for cooling FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 14
First Estimates of Impedance Effects N. Mounet, G. Rumolo 10 turns 20 turns Need feedback within 10 turns • Challenge for RF and instrumentation • Or increase the beam screen radius • Or decrease beam current TMCI is less important Multi-bunch effect at 50 K and injection (worst case) Only resistive wall (infinite copper layer assumed) FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 Many more impedance studies required 15
Electron Cloud O. Dominguez Sanchez De La Blanca Potential show stopper W/m • Critical energy 4. 3 ke. V • similar to KEKB • i. e. 100 times LHC 10 • Photon capture efficiency? • Beam stability? 0. 001 3. 1 1 Need hardware studies, simulation studies and beam experiments FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 16
Machine Protection and Friends • Identify, prioritise and study the different challenges for machine protection, radiation, injection and extraction lines, collimation, … • Develop mitigation methods • Circulating beam energy above 8 GJ (= 1 Airbus 380 at full speed) • Hydrodynamic tunneling • Probably 300 m penetration in matter (guestimate R. Schmidt) • Beam dump • Depth of shower remains roughly constant • Need to distribute beam more • Is a single beam dump sufficient? • Protection of magnets and beam against quenches • High energy stored in each magnet and in the whole sector • Develop a beam loss monitor concept. FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 17
Machine Protection and Friends II • Radiation in experiment insertions and detectors • About 100 k. W of hadron power around each experiment • About 45 times LHC, 8 times that of HL-LHC • Beam losses at injection • Impact would be much higher than in LHC • Radiation elsewhere (collimation, …) • Collimation concept, optics, spoiler distribution and design, impedance, efficiency • Number of stages, … • Increased failure rate due to radiation and large number of components • May have impact on layout, shielding needs, … FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 18
General Parameter Considerations • Synchrotron radiation and machine protection are issues and scale as • Want to have ability to minimise the beta-function • Or operate at high beam-beam tuneshift • This leads to a shorter luminosity lifetime • Shorter turn-around times are beneficial for integrated luminosity • Injectors, magnets, cooling, instrumentation, controls, … FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 19
Interaction Region and Final Focus Design R. Tomas Proof of principle: • L* = 46 m (goal >25 m) • b* = 0. 8 m (goal <1. 1 m) • 1100 m long (goal <1400 m) Would like to be able to reduce beta-function further Hardware integration and constraints Technology choices to be made Shielding of magnets is critical So excellent start, but much more work to be done FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 See R. Tomas in breakout session
Operation and Head-on Beam-beam Effects • Have chosen total tuneshift of 0. 01 • Should be conservative value • • Damping will decrease emittance and increase tuneshift Need to explore how we can control the luminosity and emittance • Noise into feedback, kickers, small beam-beam offsets, … • Need to measure emittance in collision • Can we live with larger tuneshift like in a lepton ring? • Can we just wait for an equilibrium? • Can the luminosity be controlled, i. e. not too high? • The beams will probably tend to become flat. What are the consequences? • Which experiments do we need? FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 21
Collective Effects and Mitigation • Likely will have more parasitic crossings than in LHC • Longer L* • Potentially shorter bunch spacing (down to 5 ns) • Study impact and mitigation techniques • Choice of beam parameters • Crab cavity • Wires • Electron lenses • Impedances • Collimators • … • Feedback • Tolerances and single particle effects • Much to be learned from the LHC FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 22
Injection Requirements • Need to determine with injector team • Injection energy • Time for injection • Turn-around time • Charge, emittances, time structure of beam • Depends on • Magnet swing in collider ring • Field errors and tolerances • Dynamic aperture • Field quality, imperfections • Collective effects at injection • Impedance effects • Intra-beam scattering • Electron cloud • Feedback FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 23
Beam Pipe, Vacuum, Cryogenics Need to understand how to operate in the 40 -60 K temperature window, if heat load changes Transparency of beam screen is important for vacuum quality and impedance Shielding of magnets from synchrotron radiation load • Try to use less space than in LHC but with higher load High temperature superconductor (HTS) coating? Electron cloud (photon absorption, secondary emission yield of HTS, …) Potentially photon stops, … See talk of R. Kersevan FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 24
RF Design Considerations E. Shaposhnikova 400. 8 MHz seems a good baseline • 16 MV minimum with no margin • 32 MV seems fine 200 MHz appear somewhat low • Needs higher voltage (>100 MV) • Or longer bunches (12 cm) Assumed impedance (x 2) 800 MHz appears too high Combination of 200 and 400 MHz? Feedback design is critical Emittance control also FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 Bunch length 32 MV 24 MV 16 MV
Very First Ion Considerations See M. Schaumann in breakout session Operation mode Unit LHC Design FCChh FCC-hh - Pb-Pb p-Pb 432 592 Number of bunches Part. P. bunch [108] 0. 7 1. 4 115(1. 4)/1. 4 [m] 0. 5 1. 1 [] 15. 9 8. 8 Initial luminosity [1027 cm-2 s-1] 1 3. 2 267(3. 2) Peak luminosity [1027 cm-2 s-1] 1 12. 7 5477(3356) Integr. lumi. per fill [mb-1] <15 83 30240 Total cross-section [b] 515 597 2 Initial luminosity lifetime [h] <5. 6 3. 7 3. 2 (10. 6) β-function at the IP RMS beam size at IP Much more work to be done: Improved injectors, integration into interaction region, … FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 26
The Way Forward • We want to form a collaboration • Non-committing expressions of interest for contributions by the end of May • This will largely a management activity • But it requires technical discussions to define the contents of the contributions • What are the challenges? • What needs to be done? • Would like to have some (video) meetings to • For reviews of the issues and technical discussion • Provide input for the management • Will setup mailing lists to which people can subscribe • Will start in the breakout session FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 27
FCC-hh Draft Work Breakdown Structure I FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 28
FCC-hh Draft Work Breakdown Structure II See M. Jimenez in breakout session FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 29
Conclusion • Have a first parameter list • to be able to criticise and improve it • Identified a number of critical challenges and design drivers • Need to complete the list • Your help is essential • Experience from other machines (Tevatron, SSC, KEKB, …) • Need to organise work • Workpackages, dream is that institutes take over large and selfcontained ones • Will package accordingly • Certainly welcome any contribution, even if it is smaller FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 30
Reserve FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 31
FCC-hh Study Scope In 2018 provide a CDR for a high-energy hadron-hadron collider • Conceptual baseline design (layout and parameters) that • Is feasible and supported by R&D • Fulfils the requirements of the experiments • Is consistent with the injector design • Is cost optimised • Alternatives that provide improved performance or cost but require further R&D • List of R&D challenges to be addressed for a TDR • For baseline and alternatives • Considerations on HE-LHC • Considerations on staging FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 32
Instrumentation • Need to explore the instrumentation and diagnostics requirements and identify critical issues • A couple of issues is already apparent: • Parasitic measurement of the emittance is required • Maybe use beam-beam for fine tuning of the heating • But need diagnostics • Defraction effects tend to become worse for smaller beam sizes • Aggressive transverse damping will require high-resolution BPMs • Beam is smaller and feedback needs to be faster FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 33
Beam Physics • Lattice designs • Strong interaction with hardware and beam experts • Tolerances, dynamic aperture, … • Collective effects • Intra-beam scattering, impedance effects, electron cloud, beam-beam effects • Feedback FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 34
Lattice Scaling • Using the same components and transverse dimensions • This allows to stay with the same quadrupole gradient and dipole strength • Change of technology modifies this, e. g. for FODO cell FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 35
Interaction Region and Final Focus Design Goal: • L* >= 25 m, need to iterate with the experiment • b* = 1. 1 m • Total length < 1400 m Rogelio’s approach • Based on LHC IR design • Scaled according to energy and length FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014
Interaction Region and Final Focus Design R. Tomas FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014
Interaction Region and Final Focus Design L* = 46 m R. Tomas Achieves b* = 0. 8 m About 1100 m long Need to verify separation Some iterations useful Improvements possible Excellent start Baseline appears possible Note: small beta-function can reduce synchrotron radiation FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014
400 MHz Option Loss of Landau damping Need enough voltage to keep beam stable FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 Filling factor in momentum Filling factor should not exceed 0. 8 E. Shaposhnikova 39
Electron Cloud O. Domingues Sanches De La Blanca 10 W/m 10 1 0. 001 1 2. 8 1 3. 1 Need to quantitatively asses physics parameters • Flux of photons increases with B, 1. 3 x 1017 m-1 s-1, i. e. twice LHC • Critical energy 4. 3 ke. V, i. e. 100 times LHC, similar to KEKB, photoemission yield? • Photon capture efficiency? Likely need mitigation techniques Need hardware studies, simulation studies and beam experiments FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 40
FCC-hh Workplan • Put together a team and make a design • Hardware experts and beam physicists • Started with a tentative parameter list • Develop a list of critical issues • Identify them • Prioritise them • Perform R&D • Started collecting design drivers and critical issues • Need • Contributions to the reviewing and issue identification • Senior experts can help a lot with little time investment • But more detailed studies required in some cases • Contributions to the R&D and the actual integrated design • More resources required FCC-hh Daniel Schulte FCC kick-off meeting, Geneva February 2014 41
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