1. CLIC Staged Design October 2012 D. Schulte for the CLIC collaboration

2. CDR Accelerator Volume: 3TeV Drive Beam Generation Complex Main Beam Generation Complex CLIC staging, LCWS October 2012 D. Schulte 2 Conceptual design and feasibility of 3TeV CLIC

3. CDR Accelerator Volume: 500GeV Drive Beam Generation Complex Main Beam Generation Complex CLIC staging, LCWS October 2012 D. Schulte 3 A parameter set for 500GeV Some first studies

4. Timeline D. Schulte 4 CLIC staging, LCWS October 2012 From Steinar

5. Motivation 5 CLIC staging, LCWS October 2012D. Schulte Can operate 3TeV CLIC easily down to 1TeV using full linac But below 1TeV need bypasses to extract beam early or modify BDS In this case seems a waste to not use most of the main linac A staged approach has many advantages Allows to have first physics earlier Allows to optimise for each stage better Stretches the budget Can take into account lessons of earlier stages Total cost might increase or might In practice decrease

6. CDRVolume 3Staging Scenarios Illustrate stages with two cases – 0.5, ~1.5 and 3 TeV – Energy choices we will be updated based on further LHC findings – Design based on 3TeV technology The examples are: – Scenario A is optimised for the luminosity at 500GeV – Scenario B is is cost optimised for the total project cost D. Schulte 6 CLIC staging, LCWS October 2012

7. Parameter Drivers 7 CLIC staging, LCWS October 2012D. Schulte Based on usual luminosity formula:

8. Parameter Drivers 8 CLIC staging, LCWS October 2012D. Schulte Upper limit from Luminosity spectrum (classical regime) At 3TeV maximum luminosity: L 0.01 /L>0.3 =>n γ =O(2) N/σ x ≈1x10 8 /nm (for σ z =44μm) At 500GeV comparable to ISR: L 0.01 /L≈0.6 =>n γ =O(1) N/σ x ≈2.5x10 8 /nm

9. Parameter Drivers 9 CLIC staging, LCWS October 2012D. Schulte Lower limit from all systems Upper limit from main linac lattice and structure Lower limit from Damping ring BDS RTML

10. Parameter Drivers 10 CLIC staging, LCWS October 2012D. Schulte Lower limit from all systems Upper limit from main linac lattice and structure  Easier to get N/σ x at high energy  Ratio of 3TeV to 500GeV is sqrt(1/6)  Just what we need Lower limit from Damping ring BDS RTML For fixed structure the charge is independent of energy (almost) Beamsizes roughly scale as sqrt(1/E)

11. Scenario B Scenario is chosen to reduce cost at 500GeV and the total cost of all stages Some main beam injector complex for all stages BDS can be one decelerator sector shorter at 500GeV, fits in 3TeV tunnel 12 sectors powered in second stage is maximum with one drive beam generation complex Scaled 3TeV BDS design used for stage 2 Can re-use all structures up to 3TeV D. Schulte 11 CLIC staging, LCWS October 2012

12. Scenario A Scenario is chosen for luminosity at 500GeV, L=2.3x10 34 m -2 s -1 Special structure for 500GeV leads to N=6.8x10 9 vs. 3.7 x10 9, G=80MV/m vs. 100MV/m, L=2.3x10 34 m -2 s -1 vs.L=1.3x10 34 m -2 s -1 Main beam RF pulse lengths are the same and power is comparable => can use the same drive beam generation complex Main beam injector at stage 1 needs some additional RF power Can use 80MV/m structure with the train for CLIC_G (the nominal 3TeV structure) => lose a bit of energy for stage 2 D. Schulte 12 CLIC staging, LCWS October 2012

13. Parameter Comparison unitScenario AScenario B E cms TeV0.51.43.00.51.53.0 GMV/m8080/ 100 N10 9 6.83.7 N sect 5122441224 L10 34 cm -2 s -1 2.33.25.91.31.75.9 L 1% 10 34 cm -2 s -1 1.41.32.00.71.42.0 P beam MW9.612.927.74.613.727.7 P wall MW272364589235364589 η%3.6 4.72.03.84.7 D. Schulte 13 CLIC staging, LCWS October 2012

14. Operation Scenarios StageYear 1Year 2Year 3Year 4Year 5 15%25%50%75%100% 2 and 325%50%100% Assume 200 days/year 50% useful luminosity i.e. 0.864x10 7 s/year D. Schulte 14 CLIC staging, LCWS October 2012

15. Operation Scenarios First stages takes two years longer in scenario B But second stage is one year shorter in B Total difference is only one year E cms Int(L) goal 0.5 TeV500 fb -1 1.4/1.5 TeV1500 fb -1 3 TeV2000 fb -1 D. Schulte 15 CLIC staging, LCWS October 2012

16. Luminosity Operating at Lower Energies Use 500GeV scenario A design Energy changed by gradient scaling Have to adjust bunch charge Can increase pulse length at certain energies More luminosity possible using extraction lines D. Schulte 16 CLIC staging, LCWS October 2012

17. Construction Schedule Scenario A D. Schulte 17 CLIC staging, LCWS October 2012

18. Construction Schedule Scenario A D. Schulte 18 CLIC staging, LCWS October 2012

19. Power Consumption 3TeV 19 CLIC staging, LCWS October 2012D. Schulte We optimised this part Largest contribution Strongest dependence on structure design Best understood at the time

20. Power Consumption 500GeV (A) 20 CLIC staging, LCWS October 2012D. Schulte We considered this part, which is now a much smaller fraction Need to review power consumption in many places Options for savings exist

21. Cost of the 500GeV Stage Swiss francs of December 2010 Incremental cost for B: 4MCHF/GeV -> Step to 1.5TeV is less than first stage D. Schulte 21 CLIC staging, LCWS October 2012

22. Goals for Next Phase Iterate on energy choices – 375GeV for the first stage to cover top – 1-2TeV depending on physics findings – 3TeV as current ultimate energy Focus on first energy stage – Consider upgrades Identify and review cost and power/energy saving options – Identify and carry out required R&D Re-optimise parameters – Develop an improved cost and power/energy consumption model – Iterations needed with saving options Study alternatives – E.g. first stage with klystrons Re-optimise the design Need to remain flexible, since we are waiting for LHC findings – But have some robustness of specific solutions and can anticipate this to some extent D. Schulte 22 CLIC staging, LCWS October 2012

23. Simplified Parameter Diagram Drive Beam Generation Complex P klystron, N klystron, L DBA, … Main Beam Generation Complex P klystron, … Two-Beam Acceleration Complex L module, Δ structure, … I drive E drive τ RF N sector N combine f r N n b n cycle E 0 f r Parameter Routine Luminosity, … E cms, G, L structure VariableMeaningCurrent value I drive Drive beam current101A E drive Drive beam energy2.37GeV τ RF Mainlianc RF pulse length244ns N sector Number of drive beam sectors per linac 4 N combine Combination number24 frfr Repetition rate50Hz NMain beam bunch charge in linac 3.72e9 nbnb MB bunches per pulse312 n cycle Spacing between MB bunches 6 cycles E0E0 MB energy at linac entrance 9GeV E cms Centre-of-mass energy500GeV GMain linac gradient100MV/m

24. Some Examples of Saving Options for Current Design Cost – Alternative structure fabrication – Longer main linacmodules – Maybe do not need electron pre-damping ring – CVS overdesigned for 500GeV – Main beam sources RF power quite high – Shorter drive beam pulses in first stage can reduce cost of modulator (modular design) – Combining pairs of drive beam accelerator klystrons – … Power – Permanent drive beam turn-around magnets – … 24 CLIC staging, LCWS October 2012D. Schulte

25. Exploration of Klystron-based First Stage The drive beam is necessary to reach high energies – Substantial improvement in scalability compared topreviousX-band designs At low energies klystronsmightbe competitive – Easier to qualify components No need of 100A beam for module reception tests – Need klystrons for structure testing – And they are needed for the application of the technology at other facilities (e.g. medical and light sources) Hence started to study a klystron-based first energy stage – As an alternative to a drive-beam based first energy stage – Currently at 500GeV D. Schulte 25 CLIC staging, LCWS October 2012

26. RF Unit Design NLC RF unit Chr. Adolphsen et al. For the first exploration a copy of the NLC/GLC design D. Schulte 26 CLIC staging, LCWS October 2012

27. Structure Optimisation Selected structures from optimisation for drive beam case We use a simple cost model Fixed cost per klystron/modulator/pulse compressor unit length of linac D. Schulte 27 CLIC staging, LCWS October 2012

28. Cost vs. Figure of Merit Good compromise structures are marked by arrows D. Schulte 28 CLIC staging, LCWS October 2012 F.o.M.: L/I main [arb. units] 15 3000 8000

29. Potential Klystron-based CLIC 500GeV Parameters D. Schulte 29 CLIC staging, LCWS October 2012 Case235Sc. ACLIC_G NLC G (loaded) [MV/m]57675780100 52 Str. Length: [mm]480 229 600 Δz[RF cycles]666 6616 Bunch population: N [10 9 ]5.494.957.01 6.83.727 Bunches per train:n b 382335337354312190 Pulse length: τ p [ns]244 400 Input power: P in [MW]76848974.261.354 Structure efficiency: η [%]49.541.948 39.628.5~31 Est. rel. lumi in peak @ 50 Hz1.811.442.04 2.081.0(1.15?) Klystrons per linac245422922850352023592232 Linac cost [arb. units]25282150252818011441(2771? ) Power / two linacs [MW]76.571.488.8109.773.5(167?) Linac cost [arb. units]49824442537853213800 (5003? )

30. Conclusion on Klystrons-based Stage Worthwhile to review – Could be somewhat cheaper solution at low energies – Easier to do full hardware prototyping, since no 100A beam is needed Further steps are necessary to move from an exploration to a realistic design – E.g. do we need a second tunnel, or even more? – Will iterate on the design – Can profit from past studies Mightstart some technical developments if useful – High level of synergy with other applications D. Schulte 30 CLIC staging, LCWS October 2012

31. Conclusion Have robust staged scenarios for CLIC – Two examples, since input from physics is missing Have to wait for LHC and other results – Based on the feasibility demonstration for 3TeV Lower energy stages are equally feasible – Can adjust energy stages to different physics needs This is the largest uncertainty in the concept – But concept is not yet fully optimised Will further improve the design – Further development of the technical basis Adjust design to technical limitations to be neither too aggressive nor to leave too much margin – More focus on first energy stage Including alternative technological solution – Investigation of cost and power/energy reduction options Re-optimisation of parameters and design – Systematic optimisation of the design – First results for the CLIC workshop January 2012 D. Schulte 31 CLIC staging, LCWS October 2012

32. Reserve 32 CLIC staging, LCWS October 2012D. Schulte

33. Klystron-based 500GeV Parameters D. Schulte 33 CLIC staging, LCWS October 2012

34. Scenario A D. Schulte 34 CLIC staging, LCWS October 2012

35. Scenario B D. Schulte 35 CLIC staging, LCWS October 2012

36. Higgs at 125GeV CLIC staging, LCWS October 2012 ~250GeV D. Schulte 36

37. Example of Potential SUSY Scenario CLIC staging, LCWS October 2012 Have to wait for further LHC results before a decision can be made A strategy process is active in Europe to define future directions Consistent with current LHC results D. Schulte 37

38. Parameter Choice 38 CLIC staging, LCWS October 2012D. Schulte Luminosity can be expressed as For the classical regime For the quantum regime Limitation arises from beamstrahlung

39. Luminosity Spectrum Choice 39 CLIC staging, LCWS October 2012D. Schulte At 3TeV: L 0.01 /L>0.3 =>n γ =O(2) For maximum luminosity At 500GeV: L 0.01 /L≈0.6 =>n γ =O(1) To be comparable to ISR

40. Comments Use BDS and post collision line designs for 500GeV and 3TeV – 500GeV design is shorter by one drive beam sector length – Both can be installed in the same tunnel (slightly different crossing angle) – 1.4/1.5 TeV is using the 3TeV design with magnet strengths scaled down Could be improved Use the same linac lattice, just shortened – Structure in scenario A is different from 3TeV, in scenario B it is the same Do not modify drive beam generation complex – Use only one for both linacs below 1.5 TeV – Shorten pulse length at 500GeV Main beam injectors, damping rings and RTML have the same layout – More RF power required at 500GeV in scenario A – Horizontal emittance relaxed in this scenario 40 CLIC staging, LCWS October 2012D. Schulte

41. Conclusion (for SPC) Drive beam scheme Luminosity Operation Machine Protection Main linac gradient – Ongoing test close to or on target – Uncertainty from beam loading – Generation tested, used to accelerate test beam, deceleration as expected – Improvements on operation, reliability, losses, more deceleration (more PETS) to come – Damping ring like an ambitious light source, no show stopper – Alignment system principle demonstrated – Stabilisation system developed, benchmarked, better system in pipeline – Simulations seem on or close to the target – Start-up sequence defined – Most critical failure studied – First reliability studies – Low energy operation developed CLIC staging, LCWS October 2012D. Schulte 41