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Super B Injector (2)

SuperB. Super B Injector (2). R. Boni, INFN-LNF - on behalf of the “Injector Study Group”. SuperB Mini-MAC, Frascati 16-17 July, 2008. D. Alesini, R. Boni, F. Marcellini, M. Preger, P. Raimondi, C. Vaccarezza, INFN-LNF. J. Seeman, SLAC.

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Super B Injector (2)

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  1. SuperB SuperB Injector (2) R. Boni, INFN-LNF - on behalf of the “Injector Study Group” SuperB Mini-MAC, Frascati 16-17 July, 2008 D. Alesini, R. Boni, F. Marcellini, M. Preger, P. Raimondi, C. Vaccarezza, INFN-LNF. J. Seeman, SLAC

  2. Preliminary conclusions of the Biodola-Meeting (31/05-04/06, 2008) for the SB Injector… • S-band, 100 Hz, room-temperature linac, recycling (a.m.a.p.) • PEP2 hardware (i.e. damping rings, dipoles, TL, etc …) • 2) Use of Polarized Gun • Use of Damping Rings for both e- and e+ beams • The SB-Linac is a quasi-continuous injection machine: • topping-up filling time: ≈ 12 sec per ring per min. ≈ 24 sec per min. SuperB Mini-MAC, Frascati 16-17 July, 2008

  3. GOAL • To reduce the topping-up injection time ,.. • … that is … to increase the average luminosity Talk Summary • 1. Injector layout • e+/e- injection process (damping rings & by-pass line) • Electron gun • Laser system • 5. Kickers • 6. Parameters SuperB Mini-MAC, Frascati 16-17 July, 2008

  4. INJECTOR SCHEMATIC LAYOUT e+ 4 Gev e- 7 Gev It is proposed to contemporary inject electrons and positrons in the respective rings. This can be carried out by means of simultaneous acceleration of both e- and e+ along the linac . A reduction of the rings filling time can be therefore achieved. SuperB Mini-MAC, Frascati 16-17 July, 2008

  5. SLED RF PULSE ✦ leading and trailing bunches are accelerated down the 1.2 GeV Linac [three bunches are accelerated simultaneously down the SLC injector ….] 1 μsec e+/e- INJECTION PROCESS ✦2 bunches, ≈ 50 nsec apart, are emitted by a SLC-type polarized electron gun, illuminated by laser pulses at the rep. rate of 100 Hz. ✦the bunches have different charge (1 nC and 0.1 nC), due to different laser beam energies. ✦the lower charge bunch induces weaker wake-fields in the accelerating sections, therefore it travels ahead. SuperB Mini-MAC, Frascati 16-17 July, 2008

  6. …… e+/e- INJECTION PROCESS ……cont.d ✦the leading low-charge bunch is injected, by a stripline kicker, into the e- DR; ✦ meanwhile, an electron bunch is extracted from the DR and injected into the linac by a kicker, 50 nsec before the arrival of the high-charge bunch; ✦the trailing high-charge bunch goes straight into the 2 GeV linac and is sent to the positron target. ✦the previous bunch, in turn, will be extracted after 10 msec (3 damping times) and injected into the linac, 50 nsec before the arrival of the next high-charge bunch. SuperB Mini-MAC, Frascati 16-17 July, 2008

  7. …… e+/e- INJECTION PROCESS ……cont.d ✦Spin Rotator is needed to avoid depolarization in the electron DR K K ✦Spin direction is longitudinal when exits the Gun ✦Spin direction must be perpendicular to the horizontal plane when the bunch enters the DR SuperB Mini-MAC, Frascati 16-17 July, 2008

  8. t < ΔT …… e+/e- INJECTION PROCESS ……cont.d 20 ÷ 30 nsec Kickers timing t ≈ SuperB Mini-MAC, Frascati 16-17 July, 2008

  9. BY-PASS LINE [ e+/e- INJECTION PROCESS ……] ✦the low-charge bunch is deflected, with a stripline kicker, into the by-pass line and re-injected into the linac with a delay Δ; ✦ meanwhile, a positron bunch, generated by the PS, travels through a S-band section up to rejoin with the by-passed e- bunch. L by-pass BY-PASS length = L + Δ 50 nsec - Δ SuperB Mini-MAC, Frascati 16-17 July, 2008

  10. …. BY-PASS LINE [ e+/e- INJECTION PROCESS ……] …cont.d … example of by-pass configuration ≈ L ≈ 23÷24 mt. with Δ ≈ 10nsecBPL ≈ L + 3 mt. SuperB Mini-MAC, Frascati 16-17 July, 2008

  11. …. BY-PASS LINE [ e+/e- INJECTION PROCESS ……] …cont.d … alternative by-pass configuration: ✦to avoid depolarization if the by-pass introduces a degradation. ≈ SuperB Mini-MAC, Frascati 16-17 July, 2008

  12. …. BY-PASS LINE [ e+/e- INJECTION PROCESS ……] …cont.d … alternative by-pass configuration: ✦low charge bunches go straigth through a 5 mm hole of the positron target ✦ high-charge bunches move transversely ≈ 1 cm with a pulsed bump and hit the target ✦ the produced e+ move back to the center line before the capture section capture section ≈ SuperB Mini-MAC, Frascati 16-17 July, 2008

  13. …… e+/e- INJECTION PROCESS ……cont.d ✦the trailing positron bunch is kicked into the e+ DR and damps for 10 msec; ✦ meanwhile, a damped positron bunch is kicked-out the DR and injected into the linac, 40 nsec behind the electron bunch; ✦both e- and e+ bunches are accelerated down the 3 GeV linac, up to 7 and 4 GeV respectively. SuperB Mini-MAC, Frascati 16-17 July, 2008

  14. PEP2 Damping Rings A 1.2 CeV DAMPING RING COMPLEX FOR THE STANFORD LINEAR COLLIDER, G. E. FISCHER, W. DAVIES-WHITE, T. FIEGUTH, H. WIEDEMANN Stanford Linear Accelerator Center SLAC-PUB 3170, July 1983 SuperB Mini-MAC, Frascati 16-17 July, 2008

  15. 175 psec e+ e- IMPORTANT REQUIREMENT for By-Pass and DR TL’s To position the bunches at the correct accelerating phase, the length of BP and DR TL’s must be finely tuned (± 5mm, i.e. 30 psec) SuperB Mini-MAC, Frascati 16-17 July, 2008

  16. The Polarized Electron Gun for the SLC D. C Schultz, J. Clendenin, J. Frisch, E. Hoyt, L. Klaisner, M. Woods, D. Wright, M. Zolotorev Stanford Linear Accelerator Center, SLAC-PUB-5768, March 1992 laser light input 7 x 1010 electrons in 1 nsec q ≈ 11 nC I ≈ 11 A GaAs photocathode - 120 kV SLC polarized Gun ELECTRON GUN Based on the SLC polarized electron source: ✦DC gun, ✦GaAs derivative photocathode, ✦800 nm laser, ✦SHB bunching, SuperB Mini-MAC, Frascati 16-17 July, 2008

  17. ✦RF guns with GaAs photocathode can be also considered; no SHB needed; [J.Clendenin et al., SLAC-PUB-11526, Oct. 2005] … ELECTRON GUN .. cont.d ✦2 bunches, 50 nsec apart, are emitted by a SLC-type polarized electron gun, illuminated by laser pulses, followed by SHB systems; SuperB Mini-MAC, Frascati 16-17 July, 2008

  18. LASER SYSTEM ✦ the bunches have different charge (1 nC and 0.1 nC), due to different laser beam energies. Feasible … !! Laser oscillator Transport PBS PBS Laser amplifier P-pol 50 ns ell-pol QWP 50 ns delay S-pol PBS = polarizer beam splitter (reflects s-polarization and transmits p-polarization) QWP = quarter wave plate (produces an elliptical pol. to control the two pulses intensity) ( courtesy C. Vicario ) SuperB Mini-MAC, Frascati 16-17 July, 2008

  19. Int.l Conf. on High Energy Particle Accelerators, 1995 FRASCATI PS POSITRON SOURCE NLC PS beam power = E . N . e- . fHz SuperB Mini-MAC, Frascati 16-17 July, 2008

  20. Adiabatic matching device + flux concentrator of ~ 6÷7 T peak field … POSITRON SOURCE … cont.d High Gradient (25-27 MV/m) S-band Capture Section with focusing solenoids CONVENTIONAL DEVICE SuperB Mini-MAC, Frascati 16-17 July, 2008

  21. Injection-Extraction Kickers ✦The process of the injection/extraction of e-/e+ bunches into/from the DR’s/BP requires the use of stripline kickers. ✦High performance fast kickers have been already developed (DAFNE) or designed (ILC). ✦In DAFNE, fast stripline kickers allow to inject the bunches without perturbing the adjacent ones. 45 kV 5 ns SuperB Mini-MAC, Frascati 16-17 July, 2008

  22. Kickers parameters: scaling from DAFNE (at constant deflection) 30 nsec DEFLECTION DAFNE 510 MeV Deflection Θ5 mrad (5mm @ 1 m) HV 45 kV Kicker length L 1mt. Plates distance d 5 cm Pulse width 5 nsec 10 Hz Lm·VkV Θ EGeV·dcm SuperB Injector 1.2 GeV 3 GeV Deflection Θ5 mrad 5 mrad HV 45 kV 45 kV Kicker length L 2.4 mt 6 mt. Plates distance d 5 cm 5 cm Pulse witdh ≈ 30 nsec ≈ 30 nsec 100 Hz … injection-Extraction Kickers …cont.d ✦The SuperB-Injector does not need very fast kickers. Kicker pulses with 10÷15 nsec rise/fall time and 10 nsec flat-top should be OK for the purpose. SuperB Mini-MAC, Frascati 16-17 July, 2008

  23. DAFNE KICKERS Input ports Strip ceramic supports Elliptical cross section HV feedthrough Tapered stripline Output ports (LOAD) BEAM … injection-Extraction Kickers …cont.d SuperB Mini-MAC, Frascati 16-17 July, 2008

  24. RF Linacs Layout 16 RF Stations 20 RF Stations e- > 7 GeV e+ > 4 GeV SuperB Mini-MAC, Frascati 16-17 July, 2008

  25. RF Linac Main Specs. SuperB Mini-MAC, Frascati 16-17 July, 2008

  26. e-/e+ Production Capability SuperB Mini-MAC, Frascati 16-17 July, 2008

  27. main rings filling The simultaneous injection of more than 2 bunches at a time … can be studied. It would allow to reduce even more the re-filling time. 4.2 nsec DR’s filling 4.2 nsec t Linac RF Linac RF ≈ 6 sec = 6 = 4 Rings RF DR’s RF ! The LASER system is more tricky but still feasible t ≈ 4.2 sec … about the topping-up time …. t ≈ 12 sec SuperB Mini-MAC, Frascati 16-17 July, 2008

  28. e-/e+ production with injection of “ twin bunches” 50 nsec SuperB Mini-MAC, Frascati 16-17 July, 2008

  29. Established and firm points …… ✦Room-temperature linac ✦S-band @ 2.856 GHz – 100 Hz, with SLAC-type acc. structures ✦60 MWpeak RF power sources ✦Damping Rings for both electrons and positrons ✦e+ production @ 3 GeV ✦Use of a SLC-like polarized gun SuperB Mini-MAC, Frascati 16-17 July, 2008

  30. Matters requiring R&D and/or “Study-Groups” ✦DR’s injection-extraction : kickers, spin-rotators, TL length tuning,… ✦By-pass line : kickers, length tuning ✦Electron Gun : use a copy of the SLC gun or develope a new one ? ✦Laser system ✦ TIMING & BEAM DIAGNOSTICS SuperB Mini-MAC, Frascati 16-17 July, 2008

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