1. ParameterL-bandS-bandX-band Length (m)5.04.01.0 Aperture 2a (mm) 48319 Gradient (Unloaded/Loaded) (MV/m)17/1328/2250/40 Power/structure (MW)809050 Beam Loading Compensation  T/  F TT TT Possible Configuration (struct/klyst)4/2 DesignRDS RDDS Rough LINAC parameters Based on NLC study

2. ParameterCLIC 2007Unit Initial Energy0.01GeV Final Energy0.2GeV RF Frequency1.5GHz Unloaded/Loaded Gradient21/17MV/m Power per structure80MW Linac Length15m No of Klystrons2 Transport Efficiency80 (electrons)% Electron and Positron Pre-Injector-LINAC’s S-band could be used for electrons, positron linac more challenging, solenoids over high gradient structures

3. ParameterCLIC 2007Unit Initial Energy0.2GeV Final Energy2.424GeV RF Frequency1.5 / 3GHz Unloaded/Loaded Gradient17/13 28/22MV/m Power per structure80-90MW Linac Length170 / 120m No of Klystrons 17 / 13 Transport Efficiency95% Electron and Positron Injector-LINAC Positrons need L-band, electrons can use S-band

4. ParameterCLIC 2007Unit Energy2.424GeV Initial and Final Bunch Length1.5/0.25mm Initial and Final Energy Spread0.14/0.8% RF Frequency1.5 / 3GHz RF Voltage 422/211MV Linac Length 32/ 12m No of Klystrons2/1 Transport Efficiency100% Bunch Compressor first Stage Choice of Frequency, Beam stability NLC chose L-band for tolerances

5. ParameterCLIC 2007Unit Initial Energy2.424GeV Final Energy9GeV RF Frequency3 / 12GHz Unloaded/Loaded Gradient28/22 / 50/40MV/m Power per structure~90MW Linac Length350 / 195m No of Klystrons~38 /~83 Transport Efficiency100% Booster LINAC Choice of Frequency, wake fields have to be studied due to the short bunch spacing

6. ParameterCLIC 2007Unit Energy9GeV Initial and Final Bunch Length0.25/0.044mm Initial and Final Energy Spread0.17/1.3-1.8% RF Frequency12GHz RF Voltage1500-2300MV Linac Length40-70m No of Klystrons20-35 Transport Efficiency100% Bunch Compressor second Stage Can we optimize the initial energy ?, has to be very flexible therefore we need margin

7. CLIC injectors local RF gun Unpolarized e - e + DR e + PDR Booster Linac 7 GeV 3 GHz e + BC1 e - BC1 e + BC2 e - BC2 e + Main Linac e - Main Linac 12 GHz, 100 MV/m, 21 km BDS 2.6 km BDS 2.6 km e - DR e - PDR Laser e - /e + Target Pre-injector Linac for e + 2.4 GeV Primary beam Linac for e - 2 GeV 1.5 GHz 2.424 GeV 12 GHz Laser DC gun Polarized e - Pre-injector Linac for e - 2.4 GeV 1.5 GHz Booster Linac 7 GeV

8. Central vs Local Injectors Cost, Performance, Reliability, Maintainability, Operability, upgrade scenario Cost: from NLC Injector Total: 610 M$ (CV =120,DR=104, Material=387) 500 m S-band linac: 50 M$ Pre LINAC (old): 120 M$ ~ additional cost for local injectors: 200-250 M$ Current cost estimate for 30k transfer line: 240 MCHF Performance: long low emittance transport worrisome (current ILC subject), alternative bunch compressor scenarios

9. CLIC injectors local RF gun Unpolarized e - e + DR e + PDR Booster Linac 7 GeV 3 GHz e + BC2 e - BC2 e + Main Linac e - Main Linac 12 GHz, 100 MV/m, 21 km e - DR e - PDR 2.424 GeV e + BC1 12 GHz Laser DC gun Polarized e - Pre-injector Linac for e - 2.4 GeV 3 GHz e - BC1 Booster Linac 7 GeV Laser e - /e + Target Pre-injector Linac for e + 2.4 GeV Primary beam Linac for e - 2 GeV 1.5 GHz

10. Conclusions and Remarks  Challenging but not impossible (No show stoppers found) !  Frequency choices due to acceptance, tolerances, stability and cost  No detailed overhead for beam loading compensation  Beam stability and tolerances have to be studied (wake fields in linacs, NLC did not have big margin, bunch spacing)  Pre-damping design needed (we need one for electrons too)  Polarized Positrons (how and when)  Bunch compressor studies necessary for system optimization and detailed beam parameters  Long low emittance transport has to be studied in case of central complex  Keep in mind local injectors as an option  Should we have also 1.5 GHz for the Drive Beam ?  PHIN-gun could be used for testing CLIC injector issues in the future