1. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN CLIC e + sources status L. Rinolfi with contributions from F. Antoniou, H. Braun, A. Latina, Y. Papaphilippou, F. Zimmermann / CERN R. Chehab / IPNL/IN2P3 - Lyon, V.M.Strakhovenko / BINP - Novosibirsk A. Variola, A. Vivoli / LAL - Orsay, A. Ferrari / Uppsala University E. Buylak, P. Gladkikh / NCS / KIPT - Kharkov W. Gai, W. Liu / ANL, J. Sheppard / SLAC T. Kamitani, T. Omori / KEK, M. Kuriki / Hiroshima University

2. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN The CLIC Injector complex in 2008 e - gun 3 TeV Base line configuration Laser DC gun Polarized e - Pre-injector Linac for e - 200 MeV e - /  Target Pre-injector Linac for e + 200 MeV Primary beam Linac for e - 5 GeV Injector Linac 2.2 GeV e + DR e + PDR Booster Linac 6.6 GeV 4 GHz e + BC1 e - BC1 e + BC2 e - BC2 e + Main Linac e - Main Linac 12 GHz, 100 MV/m, 21 km 2 GHz e - DR e - PDR 2 GHz 4 GHz 12 GHz 9 GeV 48 km  30 m 2.424 GeV  e  Target AMD 2.424 GeV 365 m 2.424 GeV 365 m 473 m 228 m 365 m

3. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN NLC (1 TeV) CLIC 2008 (3 TeV) ILC (Nominal) Energy E GeV8 915 Bunch population N 10 9 7.5 3.72 - 420 Nb bunches / train n b -190 3122625 Bunch spacing  t b ns1.4 0.5 (6 RF periods) 369 Train length t pulse ns266 156968625 Emittances  x,  y nm, nm.rad3300, 30 600, 108400, 24 rms bunch length  z mm 90-140 43 - 45300 rms energy spread  E  0.68 (3.2 % FW) 1.5 - 21.5 Repetition frequency f rep Hz120 505 Beam power P kW219 90630 Main beam parameters comparison At the entrance of the Main Linac for e - and e +

4. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN # of bunches per pulse # of positrons per bunch # of positrons per pulse Total charge (nC) Current (A) Exit of BC2 = Entrance of Main Linac ( 9 GeV) 3124 x 10 9 1. 24x10 12 2001.3 At exit Pre- Damping ring (2.424 GeV) 3124.4 x 10 9 1.37 x 10 12 2201.4 At exit Injector Linac (2.424 GeV) 3126.4 x 10 9 2 x 10 12 3192 At exit Pre- Injector Linac (200 MeV) 3126.7 x 10 9 2.1 x 10 12 3342.1 Assuming ~ 90 % efficiency between the PDR and the Main Linac CLIC parameters relevant for e + source Repetition frequency 50 Hz Total pulse length 156 ns Assuming ~ 70 % capture efficiency in the PDR Assuming ~ 95 % efficiency between the Pre-Injector and the Injector Linac

5. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Conventional e + source based on channelling A e - beam impinges on the crystal: - energy of 5 GeV - beam size of 2.5 mm crystal amorphous e-e- e-e- e+e+ Yield: 0.9 e + / e - @ 200 MeV R. Chehab, V. Strakovenko, A. Variola, A. Vivoli / LAL A crystal e+ source : - a 1.4 mm thick W crystal oriented along axis - a 10 mm thick W amorphous disk  Charged particles are swept off after the crystal:only  (> 2MeV) impinge on the amorphous target. The distance between the 2 targets is 2 meters. e-e- e+e+

6. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN CLIC Channeling e + source ParameterUnitCLIC Primary e - Beam EnergyGeV5 N e - /bunch10 9 7.5 N bunches / pulse-312 N e - / pulse10 12 2.34 Pulse lengthns156 Repetition frequencyHz50 Beam powerkW94 Linac frequencyGHz2 Beam radius (rms)mm2.5 Bunch length (rms)mm0.3 ParameterUnit TargetCrystalAmorph. MaterialWW Lengthmm1.410 Beam power deposited kW0.27.5 Deposited P / Beam Power %0.28 Pulse energy density 10 12 GeV/mm 2 0.6- Energy lost per volume 10 9 GeV/mm 3 0.81.9 Peak energy deposition density (PEDD) J/g6.815.5 Yield (at 200 MeV): 0.9 e + / e - Experimental limit found at SLAC: PEDD = 35 J/g

7. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Beam parameters with channeling Positrons after capture section at 270 MeV ParameterUnitCLIC Energy (E)GeV0.270 No. of e + / bunch (N)10 9 6.7 Bunch length (rms)mm8 Energy Spread (rms)%5 Longitudinal emittance (  l ) eV.m10 5 Horizontal emittance (  x ) / (  x ) mm. mrad12 / 6300 Vertical emittance (  y ) / (  y ) mm. mrad12 / 6300 Q ~ 1 nC See R. Chehab talk at this workshop

8. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN ParameterUnit Conventional target CERN simulations Channeling LAL simulations Energy (E)GeV0.2000.270 No. of e + / bunch (N)10 9 6.7 Bunch length (rms)mm58 Energy Spread (rms)%3.55 Horizontal emittance (  x ) mm. mrad92006300 Vertical emittance (  y ) mm. mrad92006300 Beam parameters comparison Accelerating gradient MV/m 15 18 Positrons after capture section at the end of the pre-injector linac

9. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Longitudinal phase space at 2.4 GeV Energy spread = 65 MeV  p/p (rms) = 2.7 % If PDR acceptance is  p/p = ± 1 % = > 82 % capture efficiency e+e+

10. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Required CLIC Pre-Damping Ring PARAMETERPDR energy [GeV]2.424 circumference [m]365.2 bunch population [10 +9 ]4.4 bunch spacing [ns]0.5 number of bunches/train312 number of trains1 store time/train [ms]20 rms bunch length [mm] at injection5 rms momentum spread [%] at injection2.7 hor. normalised emittance [  m] at ejection63 ver. normalised emittance [  m] at ejection1.5 hor./ver./ lon./ damping times [ms]1 / 1 / 0.5 number of RF cycles1 repetition rate [Hz]50 RF frequency [GHz]2 > ± 1% as small as possible

11. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN CLIC base line configuration for e + source e - /  Target Primary beam Linac for e - 5 GeV 2 GHz  e  Target AMD Pre-injector Linac for e + 200 MeV Thermionic gun For the base line configuration, based on channeling process, a solution exists with a single target station providing unpolarized e + to fulfill the CLIC parameters. The channeling process allows a good e + yield and one of the main advantage is the reduction of the beam energy deposition in the targets.

12. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN CLIC polarized e + source  Undulator  Laser Compton  Drive Beam Linac => no laser stacking cavity & no stacking in the PDR  Storage Ring => laser stacking cavity + stacking in the PDR  ERL => laser stacking cavity + stacking in the PDR

13. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Undulator K = 0.75 u = 1.5 cm L = 100 m Pre-Injector Linac G = 20 MV/m E = 200 MeV f RF = 1.5 GHz B = 0.5 T Injector Linac G = 17 MV/m E = 2.424 GeV f RF = 1.5 GHz f rep = 50 Hz CLIC 2007 based on undulator scheme 250 GeV Cleaning chicane NC Linac 2.2 GeV To the IP e - beam Ti alloy 450 m e+e+ e+e+

14. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Drive e- beam energy: 250GeV Undulator K: 0.75 Undulator period: 1.5cm Length of undulator: 100m Drift to target: 450m Accelerator gradient and focusing: 50MV/m for beam energy <250MeV, 0.5T background solenoid field focusing; for 250MeV to 2.4GeV, 25MV/m with discrete FODO set. OMD: Non immersed, ramping distance 2cm 1)7T-0.5T and 5T-0.5T, the thickness varies from 15cm to 80cm in 5cm steps; 2) the thickness fixed at 20cm, B0-0.5T, B0 varies from 1 T to 10T Photon collimator: None Target material: 0.4 rl Titanium, non-immersed Yield is calculated as Ne+ captured/Ne- in drive beam. Positron capture is calculated by numerical cut using damping ring acceptance window: +/-7.5 degrees of RF(1.3GHz),  x+  y< 0.09  m.rad,1% energy spread with beam energy ~2.4GeV Optimizing for yield W. Gai, W. Liu / ANL, J. Sheppard / SLAC

15. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Yield as function of drive beam energy & field

16. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Yield and polarization

17. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN e + injector, 2.4 GeV e - injector 2.4 GeV CLIC 3 TeV e + main linac e - main linac, 12 GHz, 100 MV/m, 21.02 km BC2 BC1 e + DR 365m e - DR 365m booster linac, 9 GeV decelerator, 24 sectors of 876 m IP BDS 2.75 km BDS 2.75 km 48.3 km drive beam accelerator 2.38 GeV, 1.0 GHz combiner rings Circumferences delay loop 72.4 m CR1 144.8 m CR2 434.3 m CR1 CR2 delay loop 326 klystrons 33 MW, 139  s 1 km CR2 delay loop drive beam accelerator 2.38 GeV, 1.0 GHz 326 klystrons 33 MW, 139  s 1 km CR1 TA R=120m TA R=120m 245m e + PDR 365m e - PDR 365m Linac with optical cavities e- beam sent to + 240 ns CLIC 20008 based on Linac scheme

18. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Linac scheme with Drive Beam ParametersCLIC Energy2.38 GeV Current101 A Nb bunches / train2904 e - Bunch population5 x 10 10 Bunch charge8.4 nC Repetition fequency50 Hz 2.4 GeV 100A e - beam  beam e + beam  to e + conv. target V. Yakimenko and I. Pogorelski (BNL) proposal for ILC to be investigated for CLIC 12 GHz

19. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN The CLIC Injector complex (Compton) 3 TeV Laser Compton ring configuration Laser DC gun Polarized e - Pre-injector Linac for e - 200 MeV e + Target Pre-injector Linac for e + 200 MeV Injector Linac 2.2 GeV e + DR 2.424 GeV 365 m Booster Linac 6.6 GeV 4 GHz e + BC1 e - BC1 e + BC2 e - BC2 e + Main Linac e - Main Linac 2 GHz e - DR e - PDR 2 GHz 4 GHz 12 GHz 9 GeV 48 km e - Drive Linac 1.3 GeV Compton ring e + PDR and Accumulator ring  2 GHz RF gun Stacking cavity 2.424 GeV 365 m 2.424 GeV 365 m 2.424 GeV 365 m

20. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN e + target Pre-injector Linac for e + 200 MeV Injector Linac 2.2 GeV e + DR 2.424 GeV 2 GHz 2.424 GeV Drive Linac 1.3 GeV Compton ring e + PDR and Accumulator ring  2 GHz 50 Hz CLIC Compton scheme Compton configuration for polarized e + and low e + /  yield RF gun 1 YAG Laser pulse 2 GHz Stacking cavity 450 turns makes 312 bunches with 4.4x10 9 e + /bunch C = 47 m, 156 ns/turn, 312 bunches with 6.2x10 10 e - /bunch 9.8x10 6 pol. e + /turn/bunch  (23-29 MeV) 7x10 8 /turn/bunch 156 ns x450 turns => 70  s pulse length for both linacs

21. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN PARAMETERPDR energy [GeV]2.424 number of trains1 rms momentum spread [%] at injection2.7 hor./ver./ lon./ damping times [ms]1 / 1 / 0.5 repetition rate [ms]20 RF frequency [GHz]2 CLIC Pre-Damping Ring optimization 1) The rms momentum spread at injection could be reduced by implementing: a) a bunch compressor at the entrance of the injector Linac b) a harmonic cavity which smooth the longitudinal distribution. 2) The transverse damping time should be ≈ 1 ms (in order to allow ≈ 10 damping times). It remains roughly 10 ms for the stacking. 3) The stacking efficiency could also be improved by putting 2 trains in the PDR.

22. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Compton e + source parameters ParametersCLIC 2007CLIC 2008ILC Energy1.3 GeV1.06 GeV1.3 GeV Circumference68 m47 m277 m RF frequency1.5 GHz2 GHz650 MHz Bunch spacing0.20 m0.15 m0.923 m Nb bunches stored311312280 e - Bunch population6.2 x 10 10 Nb optical cavities1130 Photons/bunch/turn0.7 x 10 9 2.1 x 10 9 5.8 x 10 10

23. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN CLIC Compton ring E. Bulyak, P. Gladkikh / NCS KIPT ParametersCLIC 2007CLIC 2008 Energy1.3 GeV1.06 GeV RF frequency1.5 GHz2 GHz RF voltage50 MV150 MV e - Bunch charge10 nC e - bunch length at IP5 mm Synchrotron losses400 keV/turn213 keV/turn Laser photon energy1.164 eV Laser rms pulse length0.9 mm Laser rms pulse radius0.005 mm Laser pulse energy600 mJ592 mJ Full cycle (turns)15000

24. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN e + target Pre-injector Linac for e + 200 MeV 2 GHz Drive Linac 1.06 GeV Compton ring  2 GHz 50 Hz CLIC Compton scheme Compton configuration for polarized e + and high e + /  yield RF gun 1 YAG Laser pulse Stacking cavity C = 47 m, 156 ns/turn, 312 bunches with 6.2x10 10 e - /bunch 5 x10 8 pol. e + /turn/bunch  (10 - 20 MeV) 2.1x10 9  /turn/bunch 592 mJ W sliced rod target 3 rad length => yield 0.48 e + /  => Stacking simplified E. Bulyak / NCS KIPT

25. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Energy spread in CLIC Compton ring E = 1.06 GeV Double chicane 2 RF cavities => 150 MV Emittances after 15000 turns:  H = 21 nm. rad  V = 1 nm. rad Max energy spread ~ 1 % E. Bulyak, P. Gladkikh / NCS KIPT

26. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Photons from CLIC Compton ring E. Bulyak, P. Gladkikh / NCS KIPT K: 0.5 mrad I: 0.4 mrad G: 0.3 mrad E: 0.2 mrad C: 0.1 mrad Collimation angles Max polarization ~ 75 %

27. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Studies and R&D for Compton scheme Compton ring beam dynamics and design studies (NCS-KIPT, LAL, KEK, …) Laser source (see Posipol 2006, 2007 and 2008 for companies involved ) Laser stacking cavity (KEK, LAL, IHEP, Hiroshima,… ) Target and e + capture (LAL, IPNL-Lyon, ANL, CERN, IHEP,… ) e + stacking in Pre-Damping Ring and Damping Ring (CERN,… ) Collaboration on CLIC study for e + sources is always welcome

28. 16 th June 2008 POSIPOL 2008L. Rinolfi / CERN Conclusion 1) After the CLIC major changes in 2007, studies and optimization continue on the CLIC structures and possible changes could still occur. 2) For the unpolarized e +, a conventional source, based on channeling process, fulfills the CLIC requirements with a single target station. 3) For polarized e + based on Undulator, studies continue. 4) For polarized e + based on Compton back scattering, progress have been made (Ring & Linac) but several studies and R&D are still necessary. 5) The design of a CLIC e + Pre-Damping Ring has just started. The Compton ring seems the most promising option for CLIC polarized e +.