SuperB project. Injection scheme design status R. Boni, S Guiducci, M. Preger, P. Raimondi (LNF) O. Dadoun, F. Poirier, A. Variola (IN2P3) A. Chancé, CEA Saclay XIV SuperB general meeting Frascati, 29/09/2010

Evolution of the Injection System Layout CDR2 SCHEME SHB POLARIZED SLAC GUN t1 t2 e- prod. e+ prod. e+ Inj. e- Inj. 40 msec 20 msec Damping Ring operated alternately for both electrons and positrons Main Rings injection rate: 25 Hz Klystron HV rep. rate: 50 Hz TIMING R. Boni, XiV SuperB meeting, Frascati 29-09-2010

New proposed scheme e+ e+ e+ e- PC 0.6 GeV SHB SHB positron linac e+ 1 GeV CAPTURE SECTION PC 0.6 GeV SHB THERMIONIC GUN combiner DC dipole e+ e+ BUNCH COMPRESSOR 5.7 GeV e+ 3.9 GeV e- 50 MeV CAPTURE SECTION e- POLARIZED SLAC GUN SHB 0.25 GeV Parameter Units SLC Electron charge per bunch nC 16 Bunches per pulse 2 Pulse rep rate Hz 120 Cathode area cm2 3 Cathode bias kV -120 Bunch length ns Gun to SHB1 drift cm 150 en,rms,gun (fm EGUN) 10-6 m 15 from A. Brachmann - SuperB Workshop SLAC, October 2009 Round beam Emittance @ 4.16 GeV = 1.8 nm Required bunch charge for electrons ≈ 0.3 nC … scrapers .. collimators needed R. Boni, XiV SuperB meeting, Frascati 29-09-2010

t1 e+ e- PC 0.6 GeV SHB SHB new injector scheme … t1 t2 TIMING e+ prod. e+ Inj. e- Inj. 20 msec 10 msec TIMING Electron Linac e+ CAPTURE SECTION PC 0.6 GeV SHB THERMIONIC GUN Positron Linac t1 50 MeV CAPTURE SECTION POLARIZED SLAC GUN SHB 0.25 GeV 3.9 GeV e- e- main rings R. Boni, XiV SuperB meeting, Frascati 29-09-2010

t2 e+ The most important advantage of this scheme is new injector scheme … t1 t2 e+ prod. e+ Inj. e- Inj. 20 msec 10 msec TIMING t2 e+ BUNCH COMPRESSOR 5.7 GeV e+ main rings The most important advantage of this scheme is the higher injection rate in the main rings: (DR damping time 20 msec) 50 Hz vs 25 R. Boni, XiV SuperB meeting, Frascati 29-09-2010

POSITRON LINAC > 600 MeV e- beam 1 GeV e+ CAPTURE SECTION PC the positron linac must capture high divergence particles, Proposal of the LAL-IN2P3 group Deceleration with a large iris S-band (2856 MHz) section followed by an L-band (1428 MHz), 300 MeV linac (e+ yield ≈ 30 % ± 10 MeV), immersed in a solenoidal field, followed in turn by a 700 MeV L-band linac. S-band, decelerating, large aperture, 10MV/m ≈ 1 mt long L-band linac, 13÷15 MV/m, 16 sections, 3 mt long L-band linac, 13÷15 MV/m, 8 sections, 3 mt long PC S-BAND L-BAND L-BAND 300 MeV solenoid 1 GeV ≈ 90 ÷ 120 mt R. Boni, XiV SuperB meeting, Frascati 29-09-2010

One is in operation at the Osaka Univ. (JP). … positron linac … L-band “room temperature” linacs are unusual in the field of accelerators. One is in operation at the Osaka Univ. (JP). It uses one, 3m. long acc. structure supplied with a 1300 MHz Thales klystron TH2022E Input power: 30 MW – 4 μsec – 60 pps Gradient: 13 MV/m Another one (1298 MHz) is being developed at KEK for the SuperKEKB It will use 6÷14, 2 m. long structures, supplied by four 40 MW klystron (to be developed). Input power per section: 10 MW Gradient: 12 MV/m The chosen frequency (very close to 1300) is timed with the e+ bunch separation (96.3 nsec) 1300 MHz KLY R. Boni, XiV SuperB meeting, Frascati 29-09-2010

a train of 4÷5 bunches separated by 4.2 = (6/1.428) nsec. However: … positron linac … The SuperB e+ L-band linac should operate at 1428 MHz since we accelerate a train of 4÷5 bunches separated by 4.2 = (6/1.428) nsec. However: the Thales klystron TV2022D is a 30 MWP, 60 kWAV , 7 μsec, 1300 MHz source. Thales should be available to modify the frequency if the number of sockets is >> 1. Scaling the Osaka Univ. acc. sections, the parameters of a 1428 MHz section are: Freq. 1428 MHz Type TW - CG Mode 2π/3 Length 3 m Period 7 cm Attenuation Constant 0.3 Np Shunt Impedance 45 to 50 MΩ/m Filling time 1.7 μsec Quality factor ≈ 18000 In/Out VSWR ≤ 1.2 Energy gain per section VMeV = [PZL.(1-e-2τ)]1/2 ≈ 7.8.(PMW)1/2 PIN = 30 MW ≈ 42 MeV (14 MV/m) R. Boni, XiV SuperB meeting, Frascati 29-09-2010

? … positron linac … How many structures per klystron ? Use of Pulse Compressor ? (must be designed ad hoc …) Design a more efficient L-band acc. structure, with higher shunt-impedance but smaller irises …. open questions ? Linac scheme Gradient (MV/m) N. of klystrons N. of sections Linac Length (m) 14 24 ≈ 90 10 17 34 ≈ 125 14÷16 12 R. Boni, XiV SuperB meeting, Frascati 29-09-2010

Injector RF Layout PC 17 L-band klystrons 28 S-band klystrons 2856 MHz 476 MHz 238 MHz 17 L-band klystrons PC Thermionic GUN 0.6 GeV SHB 476 MHz X SHB POL. GUN 0.25 GeV 28 S-band klystrons 238 MHz 476 MHz 2856 MHz Total RF Power Sources S-band 36 L-band 17 UHF 5 X-band 1 R. Boni, XiV SuperB meeting, Frascati 29-09-2010

Bunch Compressor for e+ ….. A. Chancé, Annecy meeting (march 2010). BUNCH COMPRESSOR 5.7 GeV e+ e+ combiner DC dipole ≈ 13.1 m R. Boni, XiV SuperB meeting, Frascati 29-09-2010

X X e+ TL length = 34 m e+ Linac DR .. Transfer Lines ….. A. Chancé, Annecy meeting (march 2010). No special dipoles X No kickers and septa, half-sine-wave kickers in the damping ring X e+ TL length = 34 m R. Boni, XiV SuperB meeting, Frascati 29-09-2010

Sub Harmonic Buncher The Bunching System performs bunch length compression from 1 nsec to 10 psec. 238 MHz 476 MHz 2856 MHz 10 ps 1 ns Standard solution, adopted in other labs (SLAC, IHEP,….) 10 ps FWHM ≈ 17 ps (±2) R. Boni, XiV SuperB meeting, Frascati 29-09-2010

Conclusions e+ e- PC 0.6 GeV SHB SHB positron linac 1 GeV e+ CAPTURE SECTION L-band PC 0.6 GeV SHB THERMIONIC GUN ≈ 170 m ≈ 350 m e+ BUNCH COMPRESSOR 5.7 GeV e+ 3.9 GeV e- 50 MeV CAPTURE SECTION POLARIZED SLAC GUN SHB 0.2 GeV ≈ 300 m e- combiner DC dipole ≈ 50 m Main Rings injection rate: 50 Hz instead of 25 Damping Ring operates just for positrons Only 2 TL’s between Linacs and D.R., instead of 4; no special dipoles; no by-pass of the PC. No long flat top kickers in the damping ring and transfer lines The gun for the positron line can be thermionic, thus delivering larger current Main Linac Klystron rep. rate: 100 Hz The e- beam emittance is higher (round beam)…. can be reduced with scrapers/collimators … (see Preger talk in Elba-meeting, june 2010) R. Boni, XiV SuperB meeting, Frascati 29-09-2010