Lepton and colliders with Energies above 3 Te

Lepton and γγ-colliders with Energies above 3 Te. V D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 1

Lo. Is # Content 34 Muon collider issues 36 FFA for muon collider 46 ALEGRO / ALIC 65 Muon collider proton-based source 66 Muon cooling issues 75 ILC at 3 Te. V 88 AFLC 102 Muon collider 103 Muon collider 135 Muon collider, LEMMA 137 Muon collider target 161 Linear collider luminosity 177 CLIC 216 Laser-plasma collider 243 Cool copper collider D. Schulte List is not complete due to several power cuts yesterday Only the papers that I printed … Lepton colliders > 3 Te. V, Snowmass 2020 2

Proposals to European Strategy (2019) Project Type Energy [Te. V] Int. Lumi. [a-1] Oper. Time [y] Power [MW] Cost ILC ee 0. 25 2 11 129 (upgr. 150 -200) 4. 8 -5. 3 GILCU + upgrade 0. 5 4 10 163 (204) 7. 8 GILCU 300 ? 1. 0 CLIC CEPC FCC-ee ee 0. 38 1 8 168 5. 9 GCHF 1. 5 2. 5 7 (370) +5. 1 GCHF 3 5 8 (590) +7. 3 GCHF 0. 091+0. 16 16+2. 6 149 5 G$ 0. 24 5. 6 7 266 0. 091+0. 16 150+10 4+1 259 0. 24 5 3 282 0. 365 (+0. 35) 1. 5 (+0. 2) 4 (+1) 340 +1. 1 GCHF 10. 5 GCHF LHe. C ep 60 / 7000 1 12 (+100) 1. 75 GCHF FCC-hh pp 100 30 25 580 (550) 17 GCHF (+7 GCHF) HE-LHC pp 27 20 20 D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 7. 2 GCHF 3

CLIC S. Stapnes et al. Designed for 3 Te. V, staged implementation Parameter and design choices for systematic cost and power optimisation Integrated peak power in beam frame is O(10 TW) Drive beam scheme is a giant power compressor D. Schulte The only of the covered projects which has been presented in Grenada for implementation Lepton colliders > 3 Te. V, Snowmass 2020 4

CLIC ECM [Te. V] 0. 38 1. 5 3. 0 L [1034 cm-2 s-1] 1. 5 3. 7 5. 9 L 0. 99 [1034 cm-2 s-1] 0. 9 1. 4 2 Int. Lumin. [ab-1] 1 2. 5 5 Cost [GCHF] 5. 9 +5. 1 +7. 3 Power [MW] 170 370 590 Note: recent improvements in power for 380 Ge. V design has not yet been integrated at 1. 5 and 3 Te. V D. Schulte Cost and power has been studied bottom-up • collaboration with industry • inclusion of site, overheads, beam sources, operational margins, cooling and ventilation, power distribution, … • reviewed Note: Even at 3 Te. V only 50 % of the total power is used to power the drive beam RF, which powers the main linac Lepton colliders > 3 Te. V, Snowmass 2020 5

CLIC Status Many components have been successfully tested CTF 3 demonstrated drive beam complex DELAY LOOP COMBINER RING CLEX DRIVE BEAM LINAC TBL Two Beam Module Lepton colliders > 3 Te. V, Snowmass 2020 D. Schulte 6

CLIC Cost and Power at Higher Energies Upgrade to 10 Te. V approximately 7 Te. V / 1. 5 Te. V x 7. 3 GCHF = 34 GCHF ? dramatic cost decrease required hard to push CLIC technology very much further different acceleration technology likely needed Require luminosity to increase as Should probably refer to L 0. 99 CLIC is slightly above goal at 3 Te. V Achievable luminosity scales as i. e. proportional to beam power for constant beam and focusing quality Beam power needs to scale with ECM 2 CLIC would need about 300 MW beam power at 10 Te. V and 2800 MW at 30 Te. V Total power consumption at least ten times higher, O(3 GW) and O(30 GW) Important improvement of beam density (emittance/focusing) innovations in a field in which one tried for decades not acceleration technology but beam sources/quality preservation/focusing Note: if we use L instead of L 0. 99, powers go down by factor 3 D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 7

Cool Copper Collider (C 3) Proposal for 2 Te. V normal conducting collider • with L = 4. 5 x 1034 cm-2 s-1 • • • E. A. Nanni, S. Tantawi et al. C-band copper accelerating structures at 80 K (nitrogen) Reduces loss of RF power in the walls by factor 2 -3 Can allow higher duty cycle, i. e. reduce peak RF power to save cost Innovative coupler design In addition, important development of RF power sources is required to reduce the cost per peak power, goal is 2 $/k. W Goal is main linac cost of 3. 2 M$/Me. V (CLIC 4. 9 MCHF/m) Two linac power (RF and cooling) 340 MW @ 2 Te. V Beam current similar to CLIC D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 8

Argonne Flexible Linear Collider (AFLC) Use dielectric structures at higher frequency • Powered by drive beam • Short RF pulses (20 ns) but same pulse charge • Higher gradients than copper (267 MV/m) • Maybe cheaper production J. Power et al. Use many locally generated drive beams Modular design can be of interest for other applications Same beam power and luminosity as for CLIC Assume higher efficiencies, only 185 MW power But have to verify high impedance structure, bunch shaping, and high-efficiency klystrons (CLIC) D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 9

ILC at 3 Te. V ILC is very mature project with focus on 250 Ge. V and upgrade to 500 Ge. V Proposal for up to 3 Te. V is very new Looking forward to seeing much more detail H. Padamse et al. Ecm [Te. V] 0. 25 0. 38 0. 5 1 2 3 L [1034 cm-2 s-1] 1. 35 1. 95 1. 8 4. 3 8. 6 6. 1 Gmax [MV/m] 31. 5 40 50 60 60 80 Cost [GILCU] 5. 5 +1. 6 +1 +4 +8 +4. 5 Power [MW] 133 158 167 232 547 596 Physics start 2035 2050 2055 2065 2075 2085 Assume improved cavity gradient and reduced losses (larger Q) • material performance Cost, power and luminosity not • improved cavity shapes very different from CLIC at 3 Te. V: • travelling wave operation 6. 1 vs. 5. 9 x 1034 cm-2 s-1 • and potentially use of Nb 3 Sn 24. 6 GILCU vs. 18. 3 GCHF 596 vs. 590 MW Total cost est. 24. 6 GILCU D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 10

Plasma-based Linear Collider B. Cros, C. Schroeder, S. Gessner et al. Laser/particle beam generates large wakefields Witness beam is accelerated with several GV/m Different flavors discussed, bubble regime, quasi-linear, hollow channel ALEGRO (by ICFA) to coordinate efforts Two distinct groups: beam-driven and laser driven plasma Ambition is 30 Te. V linear collider (at least for part of the community) Waiting to see parameters for this energy (saw one set but would need some discussion…) D. Schulte Positron acceleration is quite hard Hollow channel does not provide focusing Hard to be fully convinced of tables with the same bunch charges for electron and positron beam Less efficient positron acceleration will impact luminosity Positron acceleration R&D is essential Gamma-gamma collider might be a way out, needs only electrons Lepton colliders > 3 Te. V, Snowmass 2020 11

Plasma Issues Technology issues • power efficiency for laser systems • larger power deposition in plasma cell • staging of cells • acceleration of positrons • … Specific beam dynamics issues to match conventional solution • Power efficiency • Beam stability, actually maybe not too bad due to strong focusing • Obtaining small beam energy spread • Tight drive beam jitter tolerance (nm and nradian), should be similar for laser To go beyond 3 Te. V in energy need work on sources and focusing • without cannot judge whether plasma technology is viable for a collider D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 12

Gamma-gamma Collider Concept Based on e-e- collider Collide electron beam with laser beam before the IP Backscattered photons take up to 80% of electron energy Typically count luminosity above 60% Ecm and find roughly 10% of geometric luminosity Can trade-off spectrum quality vs. total luminosity Important R&D required if this option should be realised Might require ILC crossing angle to increase from 14 to 20 mradian D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 13

Muon Collider Muon emit almost no synchrotron radiation • can use them in a circular collider • but their lifetime is limited, • 2. 2 microseconds at rest International Muon Collider Collaboration Past effort mainly in the US • most of our knowledge is based on this Shows that luminosity per beam power increases with energy European Strategy pushed for muon collider R&D • Goal is to scientifically justify the investment into a large demonstration facility • Forming an international collaboration Focus on 3 Te. V with L = 1. 8 x 1034 cm-2 s-1 and 10+ Te. V with L = 20 x 1034 cm-2 s-1 No cost estimate yet Power estimate for 6 Te. V (MAP study) 270 MW, will make our own once we have the details For D. 14 Schulte Te. V Lepton colliders > 3 Te. V, Snowmass 2020 14

Proton-driven Muon Collider Concept MAP collaboration Short, intense proton bunches to produce hadronic showers Pions decay into muons that can be captured D. Schulte Muon are captured, bunched and then cooled by ionisation cooling in matter Acceleration to collision energy Collision Many parts have been studied but No CDR exists, no coherent baseline of machine No cost estimate Need to extend to higher energies (10+ Te. V) But did not find something that does not work Lepton colliders > 3 Te. V, Snowmass 2020 15

Tentative Target Parameters Parameter Unit 3 Te. V 10 Te. V 14 Te. V L 1034 cm-2 s-1 1. 8 20 40 N 1012 2. 2 1. 8 fr Hz 5 5 5 Pbeam MW 5. 3 14. 4 20 C km 4. 5 10 14 <B> T 7 10. 5 εL Me. V m 7. 5 σE / E % 0. 1 σz mm 5 1. 07 β mm 5 1. 07 ε μm 25 25 25 σx, y μm 3. 0 0. 9 0. 63 Based on MAP source and concept The same source for all energies Achieves physics goal of D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 16

Design Status As you just heard in detail Key systems designed for 3 Te. V in US A number of key components has been developed Cooling test performed according to theory MICE (UK) But no CDR, no integrated design, no reliable cost estimate More work to be done, e. g. substantial, 6 D cooling Mu. Cool: >50 MV/m in 5 T field FNAL Breakthrough in HTS cables FNAL 12 T/s HTS 0. 6 T max NHFML 32 T solenoid with lowtemperature HTS D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 Mark Palmer 17

Key Issues • Have to minimise increase of environmental radiation level by neutrinos • e. g. put machine on movers • Decaying muons induce detector background • shielding, detector design, event reconstruction, … • recent results at 1. 5 Te. V are encouraging (D. Lucchesi et al. ) • LHC colleges are not too worried • High-energy complex performance, cost and power • Collider ring magnets, protection from muon decays • Efficient RF system for high bunch charge • … • Muon beam production • Robust proton target • Efficient muon beam cooling, magnets, RF, targets, … • Exploration of alternative options, e. g. use of positrons (LEMMA) D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 18

A Potential Way Forward 18 17 16 15 14 13 12 11 10 9 8 7 Technically limited 6 5 4 3 2 1 Exploratory Definition phase Collider Design Baseline design Design optimisation Project preparation. Approve Test Facility Construct Exploit Technologies Design / models D. Schulte Prototypes / t. f. comp. Ready to decide on test facility Cost scale known Prototypes / pre-series Ready to commit Cost know Lepton colliders > 3 Te. V, Snowmass 2020 Ready to construct 19

Conclusion • • • A mature approach up to 3 Te. V exists for e+e-: CLIC Alternative main linac technologies are being proposed – important R&D will be required, need to consider carefully promises and risks To go beyond 3 Te. V have to address both, cost and power – Advanced acceleration might reduce cost, but have many technology challenges – Need innovation to produce more luminosity per beam power • not easy, have worked on this over decades • I think this is indispensible in addition to technology effort, can be shared by different technologies Muon collider is alternative approach – Integrated design to ensure coherence and optimise for cost and power – R&D effort required to prove feasibility of high luminosity Should have coherent approach to expectations and risks – participants from different projects Need feedback on L vs. L 0. 99 from physics D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 20

Reserve D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 21

Potential Facility Table CLIC CCC ILC AFLC MC MC Beam Energy [Te. V] 1. 5 1. 5 7 Luminosity [1034 cm -2 s-1] 5. 9 4. 5 6. 1 ~6 1. 8 (4. 4 in MAP study) 40 Beam power [MW] 28 18 ? 28 5. 3 20 Site power [MW] 590 340 two linac 596 185 230 MAP study ? 18. 3 CHF estimate 6. 4 $ goal for linacs 24. 6 ILCU estimate ? ? ? Cost [GUnit] D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 22 22

Potential Facility Table CLIC MC MC PWFA LPA Beam Energy [Te. V] 1. 5 7 5 15 Luminosity [1034 cm 2 s-1] 5. 9 1. 8 40 10 10 1000 IP Beam sizes x/y [nm] 40/1 3000/3000 600/600 100 / 0. 6 10 / 0. 5 0. 2 / 0. 2 Rms bunch length [μm] beta* [mm] 44 / 0. 068 5000/5 1070/1. 07 20 / 0. 1 8. 5 / 0. 2 Rep. frequency [Hz] 50 x 312 5 (66, 667) 5 (21, 429) 5 x 103 47 x 103 Bunch spacing [μs] 0. 5 x 10 -3 15 46. 7 200 21 21 Beam power [MW] 28 5. 3 20 80 ? ? Site power [MW] 590 < 230 ? 537 315 linacs 3151 linacs 18. 3 CHF ? ? ? Cost [GUnit] LPA and PWFA taken from Joint AF-EF Meeting of Future Colliders: Day 2, July 1, Lo. Is did not specify luminosity, need to confirm numbers D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 23 23

CLIC D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 24

Laser-plasma Collider Carl Schroeder, July 1, 2020, Joint AF-EF Meeting of Future Colliders: Day 2 D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 25

Beam-driven Plasma Collider Spencer Gessner, July 1, 2020, Joint AF-EF Meeting of Future Colliders: Day 2 D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 26

Target Parameter Examples From the MAP collaboration: Proton source Even at 6 Te. V above target luminosity with reasonable power consumption But have to confirm power consumption estimates D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 27

Tentative Target Parameters Parameter Unit 3 Te. V 10 Te. V 14 Te. V L 1034 cm-2 s-1 1. 8 20 40 N 1012 2. 2 1. 8 fr Hz 5 5 5 Pbeam MW 5. 3 14. 4 20 C km 4. 5 10 14 <B> T 7 10. 5 εL Me. V m 7. 5 σE / E % 0. 1 σz mm 5 1. 07 β mm 5 1. 07 ε μm 25 25 25 σx, y μm 3. 0 0. 9 0. 63 Based on MAP source and concept The same source for all energies Achieves physics goal of D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 28

Linear Collider Luminosity and Efficiency Came up several times Luminosity depends on efficiency and beam quality (add formulae that has not been shown) Beamstrahlung limited by physics requirements Bunch length from acceleration constraints Beam quality and focusing design RF-to-beam efficiency Power consumption PWFA: High beam-to-beam efficiency obtained (O(30%)) for electrons But beam quality is open question LPA: laser efficiency is a concern D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 29

LC - Luminosity Scaling with Energy For constant technology factor does not change General luminosity formula If βx can be reduced Limit from beamstrahlung Limit for optimum vertical betafunction D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 If βy can be reduced 30

Luminosity For constant technology • keep bunch charge and length constant • emittances and betafunctions are constant Luminosity per beam power independent of energy For CLIC about > 200 MW beam power to reach 40 x 1034 cm-2 s^-1 at 14 Te. V Plasma colliders can have shorter bunches • reduces beamstrahlung allows to reduce horizontal beamsize reduce horizontal emittance or betafunction Can reduce vertical betafunction Can always profit from smaller vertical emittance Ben’s beam with optimum betafunctions requires 24 MW beam power for L = 40 x 1034 cm-2 s^-1 at 14 Te. V eight times better than CLIC, eight times shorter bunch D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 But need to achieve smaller emittances and betafunctions tried hard for linear colliders 31

Positron Current Impact Small charge in positron beam N+ = α N for same spot size luminosity scales as L ≈ α L 0 Beam reduces radiation of electron beam more collisions at full energy N+ = 0. 1 NAlmost no radiation from electrons Can about double radiation for positrons Can reduce horizontal beamsize by sqrt(1/8) provided we can achieve this Only loose about factor 4 in luminosity N+ < 0. 1 Nloose about linearly with L ≈ 2. 5 α L 0 N+ = 0. 3 Nloose about factor 2 Need to maintain reasonable positron current Need to push horizontal beam size even further Note: Background is not forward-backward symmetric D. Schulte Lepton colliders > 3 Te. V, Snowmass 2020 32