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ERL Compton scheme for CLIC

ERL Compton scheme for CLIC. L. Rinolfi (CERN) and T. Omori (KEK) many thanks to all Posipol collaboraters CLIC WS 15-Oct-2009 CERN. World-wide PosiPol Collaboration. Collaborating Institutes: BINP, CERN, DESY, Hiroshima, IHEP, IPN, KEK, Kyoto, LAL, CELIA/Bordeaux, NIRS, NSC-KIPT,

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ERL Compton scheme for CLIC

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  1. ERL Compton scheme for CLIC L. Rinolfi (CERN) and T. Omori (KEK) many thanks to all Posipol collaboraters CLIC WS 15-Oct-2009 CERN

  2. World-wide PosiPol Collaboration Collaborating Institutes: BINP, CERN, DESY, Hiroshima, IHEP, IPN, KEK, Kyoto, LAL, CELIA/Bordeaux,NIRS, NSC-KIPT, SHI, Waseda, BNL, JAEA and ANL Sakae Araki, Yasuo Higashi, Yousuke Honda, Masao Kuriki, Toshiyuki Okugi, Tsunehiko Omori, Takashi Taniguchi, Nobuhiro Terunuma, Junji Urakawa, Yoshimasa Kurihara, Kazuyuki Sakaue, Masafumu Fukuda, Takuya Kamitani, X. Artru, M. Chevallier, V. Strakhovenko, Eugene Bulyak, Peter Gladkikh, Klaus Meonig, Robert Chehab, Alessandro Variola, Fabian Zomer, Alessandro Vivoli, Richard Cizeron, Viktor Soskov, Didier Jehanno, M. Jacquet, R. Chiche, Yasmina Federa, Eric Cormier, Louis Rinolfi, Frank Zimmermann, Kazuyuki Sakaue, Tachishige Hirose, Masakazu Washio, Noboru Sasao, Hirokazu Yokoyama, Masafumi Fukuda, Koichiro Hirano, Mikio Takano, Tohru Takahashi, Hirotaka Shimizu, Shuhei Miyoshi, Yasuaki Ushio, Tomoya Akagi, Akira Tsunemi, Ryoichi Hajima, Li XaioPing,Pei Guoxi,Jie Gao, V. Yakinenko, Igo Pogorelsky, Wai Gai, and Wanming Liu POSIPOL 2010 Tsukuba POSIPOL 2006 CERN Geneve 26-27 April POSIPOL 2008 Hiroshima 16-18 June http://posipol2006.web.cern.ch/Posipol2006/ http://home.hiroshima-u.ac.jp/posipol/ POSIPOL 2007 LAL Orsay 23-25 May POSIPOL 2009 Lyon 23-26 June http://indico.cern.ch/internalPage.py?pageId=1&confId=53079 http://events.lal.in2p3.fr/conferences/Posipol07/

  3. Two ways to get pol. e+ (1) Helical Undurator e- beam E >150 GeV Undulator L > 200 m (2) Laser Compton

  4. Two ways to get pol. e+ (1) Helical Undurator e- beam E >150 GeV Undulator L > 200 m Our Proposal (2) Laser Compton

  5. Why Laser-Compton ? i) Positron Polarization. ii) Independence Undulator-base e+ : use e- main linac Problem on design, construction, commissioning, maintenance, Laser-base e+ : independent Easier construction, operation, commissioning, maintenance iii) Polarization flip @ 50 Hz iv) High polarization v) Low energy operation (exsmpl: Ecm = 230 GeV) Undulator-base e+ : not suitable Laser-base e+ : no problem

  6. Three of Compton schemes for CLIC and ILC 1. Ring-based Compton. 2. ERL-based Compton. 3. Linac-based Compton.

  7. Three of Compton schemes for CLIC and ILC 1. Ring-based Compton. My talk today 2. ERL-based Compton. 3. Linac-based Compton.

  8. ERL Compton Re-use Concept laser pulse stacking cavities efficient photon beam positron stacking in main DR ERL e-Linac or E-gun efficient electron beam to main linac

  9. 325 MHz 31 MHz Optical Cavity for Pulse Laser Beam Stacking Reuse high power laser pulse by optical cavity Laser-electron small crossing angle Laser bunches collision is not head-on Lcav = n  Lcav = m Llaser Cavity Enhancement Factor = 1000 - 105

  10. ERL based Compton source laser-pulse stacking cavity 1.8 GeV 1.8 GeV - E_loss gamma rays E_loss : beam energy loss cased by Compton scatterings 10 MeV 1.8 GeV - E_loss superconducting electron linac 1.8 GeV 1.8 GeV 10 MeV dump 10 MeV injection 10 MeV RF-Gun accelerating electron bunches (take energy from acc. cavities) decelerating electron bunches (give energy to acc. cavities)

  11. Points of ERL: 1 Re use: Energy of electron beam Throw away: electron beam.

  12. Points of ERL: 1 Re use: Energy of electron beam Throw away: electron beam. Points of ERL: 2 Fresh, high quality beam Small spot size (10 micron) at CP.

  13. Points of ERL: 1 Re use: Energy of electron beam Throw away: electron beam. Points of ERL: 2 Fresh, high quality beam Small spot size (10 micron) at CP. Points of ERL: 3 Short bunch (< 1 ps) at CP. (non head-on) Beam compression (3 ps to < 1 ps)

  14. ERL based Compton source laser-pulse stacking cavity 1.8 GeV 1.8 GeV - E_loss gamma rays E_loss : beam energy loss cased by Compton scatterings compression decompression 10 MeV 1.8 GeV - E_loss superconducting electron linac 1.8 GeV 1.8 GeV 10 MeV dump 10 MeV injection 10 MeV RF-Gun accelerating electron bunches (take energy from acc. cavities) decelerating electron bunches (give energy to acc. cavities)

  15. Points of ERL: 1 Re use: Energy of electron beam Throw away: electron beam. Points of ERL: 2 Fresh, high quality beam Small spot size (10 micron) at CP. Points of ERL: 3 Short bunch (< 1 ps) at CP. Beam compression (3 ps to < 1 ps) Points of ERL: 4 Need steady exchange of energy: Accel-Bunches, Decel-Bunches, Klystrons Need CW operation

  16. CLIC e+ source parameters • 4.2 x 109 e+/bunch (exit of Pre Damping Ring:PDR) • E (PDR and DR) = 2.86 GeV • Tb-to-b = 0.5 ns • CDR = CPDR ~ 400 m • Nbunch = 312 / trian • Frep = 50 Hz (Ntrain = 50/sec)

  17. Compare ERL and CLIC ERL : CW device CLIC : short pulse 150 ns & high rep. 50 Hz (312 bunches w/ 0.5 ns spacing) How to adapt ERL to CLIC?

  18. Solution Put 2 stacking rings (SRs) between ERL and PDR to separate stacking and damping functions. ERL 1 1 321 321 2 2 3 3 SR1 SR2 2 1 3 312 C = 48m C = 48m 47 m PDR C = 400 m Kill 321 - 312 = 9 bunches

  19. Configuration

  20. Stacking Ring (SR) SR makes stacking and pre2damping • C = 48.15 m • 0.156s / turn • 321 bunches in a ring 321 x 0.5 ns x 0.3 m/ns = 48.15 m • stack in the same bucket every 64th turn (injected beam: Tb-to-b = 32 ns --> explain later) • N of stacking in the same bucket = 2003 64x2003 = 128 192 turns = 1.2 x 105 turns 0.156 s x 1.2 x 105 = 19.9979 ms  20 ms • "Stacking = 20 ms" + "Damping in SR = 20 ms" --> total 40 ms /cycle (25 Hz) match

  21. Stacking in a SR : part 1 We give labels "1" to "321" to the buckets in the SR. 1 321 2 320 3 64 257 65 SR C = 48 m 193 129

  22. Stacking in a SR : part 2 • 1st turn 1 65 129 193 257 • 2nd turn 321 64 128 192 256 • 3rd turn 320 63 127 191 255 • • • 64th turn 2 66 130 194 258 • 65th turn 1 65 129 193 257 • 66th turn 321 64 128 192 256 •

  23. Timing Chart Time [ ms ] 0 20 40 60 80 100 120 140 ERL(CW) to SR1 to SR1 to SR1 to SR1 to SR2 to SR2 to SR2 SR1(25Hz) stack damp stack damp stack damp stack to PDR to PDR to PDR SR2(25Hz) stack damp stack damp stack damp to PDR to PDR to PDR from SR1 from SR1 from SR1 from SR2 from SR2 from SR2 PDR(50Hz) DR(50Hz)

  24. Number of g-rays/ e+s • e- beam (ERL) 3 x 109 e-/bunch E = 1.8 GeV • Laser 600 mJ / cavity 1 cavity in ERL • 5 x 108g-rays/bunch • 2.5 x 106 e+/bunch • 5 x 109 e+/bunch (CLIC requires 4.2 x 109) collision thin conversion target: yield 0.5 % 2003 stacking in the same bucket

  25. ERL • 3 x 109 e-/bunch • E = 1.8 GeV • Tb-to-b = 32 ns • Fref = 31.25 MHz • FRF = 1 GHz (for example) Tb-to-b = 32 nsec 1 nsec (1 GHz) Tb-to-b = 32 nsec Accelerating bunches Decelerating bunches

  26. Summary • ERL scheme can provide small spot size and short pulse at the laser-electron collision point. Especially short pulse (< 1ps) is big advantage. • A solution where stacking and damping are decoupled seems possible to fulfill CLIC requirements with an ERL scheme • Challenge remains to be demonstrated in order to make 2000 stacking in a same bucket. There was a simulation for ILC-ERL-Compton by F. Zimmerman. The result was encouraging. • Stacking ring with 48 m circumference and 1 GeV is also a challenge. • The cost increase with 2 storage rings is not an issue compared to the rest of the complex.

  27. Backup slides

  28. Status of Compton Source Proof-of-Principle demonstration was done. ATF-Compton Collaboration Polarized -ray generation: M. Fukuda et al., PRL 91(2003)164801 Polarized e+ generation: T. Omori et al., PRL 96 (2006) 114801 We still need many R/Ds and simulations. We have 3 schemes. Choice 1 : How to provide e- beam Storage Ring, ERL, Linac Choice 2 : How to provide laser beam Wave length (=1m or =10m ) staking cavity or non stacking cavity Choice 3 : e+ stacking in DR or Not

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