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Compton Based Polarized Positron Sources for e + /e - Linear Colliders

Compton Based Polarized Positron Sources for e + /e - Linear Colliders. A. Vivoli* Thanks to : A. Variola, R. Chehab, T. Omori, F. Zimmermann, E. Bulyak, M. Kuriki,. * E-mail : Alessandro.Vivoli@cern.ch. CONTENTS. Introduction to Pol. e + Sources Simulation Results

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Compton Based Polarized Positron Sources for e + /e - Linear Colliders

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  1. Compton Based Polarized Positron Sources for e+/e- Linear Colliders A. Vivoli* Thanks to : A. Variola, R. Chehab, T. Omori, F. Zimmermann, E. Bulyak, M. Kuriki, * E-mail : Alessandro.Vivoli@cern.ch

  2. CONTENTS • Introduction to Pol. e+ Sources • Simulation Results • Different Schemes for Compton Sources • Possible application to CLIC • Conclusions A. Vivoli, Compton Based Polarized Positron Sources

  3. MOTIVATION For next e-e+ colliders polarization of both e- and e+ would be very useful. (G. Moortgat-Pick et al., Physics Reports 460 (2008) 131-243 ) A. Vivoli, Compton Based Polarized Positron Sources

  4. General Scheme of P.P.S. (Polarized) e+ are not available in nature! Target • Positron Source: • Primary e- beam generation • Generation of Gamma rays (Ondulator, Compton, …) • Pair production in a target (W, Ti, Liquid Pb, …) • Capture of e+ • Acceleration and Transport • Stacking in a Damping Ring A. Vivoli, Compton Based Polarized Positron Sources

  5. Compton Backscattering l e- l’ Ee-= gmec2 • Linear Compton Backscattering • l’ ≈ l /(4g2) • Optimum Energy for e+ production and capture: Eg ≈ 30 MeV • l ≈ 1 mm Eg≈ 4g2hc/ l ≈ 30 MeV g≈ 2500 Ee- ≈ 1.3 GeV • , r02 = 6.66 ·10-25 cm2 A. Vivoli, Compton Based Polarized Positron Sources

  6. Compton e+ Sources • Proof-of-principle demonstration: T. Omori et al., PRL 96 (2006) 114801 • Compton Ring + Stacking Cavity • ERL + Stacking Cavity • (T. Omori, J. Urakava, M. Kuriki – KEK) • (A. Variola, F. Zomer, R. Chehab – LAL) • (E. Bulyak, P. Gladkikh – NSC KIPT) • Linac + CO2 laser NO NEED STACKING • (V. Yakimenko, I.V. Pogorelsky - BNL) NEED STACKING IN DR Very interesting, not treated here. A. Vivoli, Compton Based Polarized Positron Sources

  7. Stacking Cavity Laser power = W Cavity length = L Laser frequency = flaser Energy gain = G flaser ≈ Elaser= W/ flaser ·G A. Vivoli, Compton Based Polarized Positron Sources

  8. By T. Omori A. Vivoli, Compton Based Polarized Positron Sources

  9. By T. Omori A. Vivoli, Compton Based Polarized Positron Sources

  10. Polarized Positron Source ERL Scheme e+ e- e- e- g e+ Compton cavities 4.8 (2.2) GeV superconducting linac with quadrupole focusing Target 1.8 GeV superconducting linac Capture Section with solenoid (+ Bunch Compressor) Up to ~150 (200) MeV (PRE)Damping Ring e-injector + Bunch Compressor A. Vivoli, Compton Based Polarized Positron Sources

  11. Gamma Production Scheme (by T. Omori) A. Vivoli, Compton Based Polarized Positron Sources

  12. A. Vivoli, Compton Based Polarized Positron Sources

  13. Simulation (CAIN) Photons 1.8 GeV – 5 IP Mean Energy : 27,7 MeV Number of photons simulated : 75177 105 A. Vivoli, Compton Based Polarized Positron Sources

  14. COMPARISON OF DIFFERENT ENRGY SCHEMES 1.3 GeV – 5 IP 1.3 GeV – 10 IP 1.8 GeV – 5 IP A. Vivoli, Compton Based Polarized Positron Sources

  15. Positron Production (EGS) • Number of e+ : 6470 105 • Mean energy : 17.627 MeV • Polarization : 21% 1.8 GeV – 5 IP A. Vivoli, Compton Based Polarized Positron Sources

  16. Scheme of the Capture Section (up to 180 MeV) 79 Cavities 5 - 10 Interaction points e- source Target AMD e- e+ (180 - 200 MeV) e- g e- g 1.3 – 1.8 GeV ERL Solenoid Dump e- A. Vivoli, Compton Based Polarized Positron Sources

  17. Adiabatic Matching Device • Length: L = 50 cm • Magnetic field at the target : B0 = 6 T • Magnetic field at the end : B(L) = 0.5 T • Magnetic Field Behaviour : A. Vivoli, Compton Based Polarized Positron Sources

  18. Beam parameters Parameters of the positron beam at the exit of the target (z = 0 cm) and at the exit of the AMD (z = 50 cm) Z = 0 Z = 50 Capture percentage : 52,12 % A. Vivoli, Compton Based Polarized Positron Sources

  19. Captured Positron Beam A. Vivoli, Compton Based Polarized Positron Sources

  20. New Cavity (1.3 GHz, SW, 100 KW CW) A. Vivoli, Compton Based Polarized Positron Sources

  21. Pre-accelerator Solenoid • Magnetic Field = 0.5 T • Length = ~ 57 m Accelerating Cavities: • Length = 56 cm • Aperture = 2. cm • Average accelerating Field = ~ 3.3 MV/m • Number of cavities = 79 Drift length between cavities = 13 cm A. Vivoli, Compton Based Polarized Positron Sources

  22. Beam parameters II Parameters of the positron beam at the exit of the AMD (z = 50 cm) and at the exit of the solenoid (z = 5775 cm) Z = 50 Z = 5775 Multiple stacking needed A. Vivoli, Compton Based Polarized Positron Sources

  23. COMPARISON OF YIELD & POLARIZATION FOR DIFFERNET Ee- A. Vivoli, Compton Based Polarized Positron Sources

  24. Capture Section (+ CHICANE) Adiabatic Matching Device Chicane Pre-accelerator Target From Compton Cavities e- To the accelerator g g e+ Bending Magnets Drift f= 8 - 10 cm Solenoid Cavities Magnetic field Electric field A. Vivoli, Compton Based Polarized Positron Sources

  25. Bending angle = 16 deg drift length = 200 cm BM length = 60 cm A. Vivoli, Compton Based Polarized Positron Sources

  26. Beam parameters II Parameters of the positron beam at the exit of the solenoid (z = 5775 cm) and at the exit of the chicane (z = 6540 cm) Z = 5775 Z = 6540 A. Vivoli, Compton Based Polarized Positron Sources

  27. RESULTS (180 MeV) A. Vivoli, Compton Based Polarized Positron Sources

  28. Capture Section (+ B.C.) Adiabatic Matching Device Chicane Pre-accelerator Bunch Compressor Target From Compton Cavities e- g g e+ To the accelerator Bending Magnets Drifts Solenoid Cavities Magnetic field Electric field A. Vivoli, Compton Based Polarized Positron Sources

  29. Bunch Compressor Tesla Cavities e+ Bending Magnets Drifts Triplets A. Vivoli, Compton Based Polarized Positron Sources

  30. Beam parameters III Parameters of the positron beam at the exit of the chicane (z = 6540 cm) and at the exit of the BC (z = 7961 cm) Z = 6540 Z = 7961 A. Vivoli, Compton Based Polarized Positron Sources

  31. 5 GeV superconducting LINAC Quadrupoles length : L = 10 – 20 cm Field at pole tip : B = 3 – 5 KG Quadrupoles aperture : R = 5 cm Cavities length : l = 1.25 m Mean accelerating field : E = 9 MV/m Cavities aperture : r = 3.5 cm A. Vivoli, Compton Based Polarized Positron Sources

  32. Beam parameters IV Parameters of the positron beam at the exit of the BC (z = 7961 cm) and at the exit of LINAC (z ~ 105 cm) Z= 7961 Z~ 105 Yield e+/g = 0.9 % A. Vivoli, Compton Based Polarized Positron Sources

  33. Polarization Estimations of polarization are made assuming that the initial polarization of the positrons doesn’t change. P = 60.3 % A. Vivoli, Compton Based Polarized Positron Sources

  34. STACKING SIMULATIONS By F. ZIMMERMANN A. Vivoli, Compton Based Polarized Positron Sources

  35. 24.6 ns 6.15 ns e+ bunches from ERL DR frep = 40.8 MHz : 1st turn of DR stacking (1) 1st turn begin 24.6 ns (2) 1st turn end 6.15 ns e+ bunches from ERL DR By T. Omori A. Vivoli, Compton Based Polarized Positron Sources

  36. (b) frep = 40.8 MHz : 2nd turn of DR stacking 24.6 ns (1) 2nd turn begin 6.15 ns e+ bunches from ERL DR 24.6 ns (2) 2nd turn end 6.15 ns e+ bunches from ERL DR By T. Omori A. Vivoli, Compton Based Polarized Positron Sources

  37. (b) frep = 40.8 MHz : 3rd turn of DR stacking 24.6 ns (1) 3rd turn begin 6.15 ns e+ bunches from ERL DR 24.6 ns (2) 3rd turn end 6.15 ns e+ bunches from ERL DR By T. Omori A. Vivoli, Compton Based Polarized Positron Sources

  38. 24.6 ns (b) frep = 40.8 MHz : 4th turn of DR stacking 24.6 ns (1) 4th turn begin 6.15 ns e+ bunches from ERL DR (2) 4th turn end 6.15 ns e+ bunches from ERL DR By T. Omori A. Vivoli, Compton Based Polarized Positron Sources

  39. (b) frep = 40.8 MHz : 5th turn of DR stacking 24.6 ns (1) 5th turn begin 6.15 ns e+ bunches from ERL DR 24.6 ns (2) 5th turn end 6.15 ns e+ bunches from ERL DR By T. Omori A. Vivoli, Compton Based Polarized Positron Sources

  40. Compton source megatable - 1 A. Vivoli, Compton Based Polarized Positron Sources

  41. Design of the Energy Compressor Chicanes Tesla Cavities ….. Quadrupoles Beam ellipse in the longitudinal phase space (z,E) A. Vivoli, Compton Based Polarized Positron Sources

  42. FINAL RESULTS A. Vivoli, Compton Based Polarized Positron Sources

  43. Compton Ring (CR) vs Compton Energy Recovery Linac (C-ERL) A. Vivoli, Compton Based Polarized Positron Sources

  44. REQUIREMENTS • ILC • Ne+ = 2·1010 x 2625 = 5.25·1013 e+ /pulse tpulse ~ 22 ms • fr= 5 Hz 2.625·1014 e+/s • Polarization : Min 30% Possibly ≥ 60% • CLIC • Ne+ = 4·109 x 312 = 1.248·1012 e+/pulse tpulse = 156 ns • fr= 50 Hz 6.24·1013 e+/s • Polarization : Min 30% Possibly ≥ 60% A. Vivoli, Compton Based Polarized Positron Sources

  45. ILC - CR By T. Omori, A. Variola et al. A. Vivoli, Compton Based Polarized Positron Sources

  46. 2 10exp 8 positrons 100 bunches T b_b = 18.45 ns C=553 m Gamma Ng = 4 10exp10 bunch 1.3 GeV Linac CW linac 3.5 GeV Collision 226 turns (416micro sec) then wait 2 msec. Single cycle ~ 2.5 m sec. Stack 40 times 416 microsec 564 bunches Tb_b =6.15ns C=1040m Tcool = 2 msec wait = 2 msec single cycle ~2.5 msec Waiting time Between stack In the same bucket = 1/200 Tcool CW linac 1.5 GeV To DR Transfer at 400 Hz It means that in 100 msec => 40 shots Total 320 stackings/bunch in main-DR

  47. Electron Storage Ring 1.8 GeV 1.8 GeV booster Compton Ring Scheme for ILC • Compton scattering of e- beam stored in storage ring off laser stored in Optical Cavity. • 5.3 nC 1.8 GeV electron bunches x 5 of 600mJ stored laser -> 2.3E+10 γ rays -> 2.0E+8 e+. • By stacking 100 bunches on a same bucket in DR, 2.0E+10 e+/bunch is obtained. A. Vivoli, Compton Based Polarized Positron Sources

  48. ILC – C ERL By T. Omori, A. Variola et al. A. Vivoli, Compton Based Polarized Positron Sources

  49. ERL scheme for ILC High yield + high repetition in ERL solution. 0.48 nC 1.8 GeV bunches x 5 of 600 mJ laser, repeated by 54 MHz -> 2.5E+9 γ-rays -> 2E+7 e+. Continuous stacking the e+ bunches on a same bucket in DR during 100ms, the final intensity is 2E+10 e+. Conversion Target To Positron Liniac Photon Capture System Laser Optical Cavities RF Gun Dump SC Linac 1.8 GeV 1000 times of stacking in a same bunch A. Vivoli, Compton Based Polarized Positron Sources

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