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BINP Tau-Charm Project. E.Levichev For the BINP C-Tau team. 3 February 2010, KEK, Tsukuba. Outline 1. Introduction of Crab Waist collision approach 2. Scientific program and specifications 3. Optics 4. FF and QD0 5. Polarization insertions 6. Energy calibration. Crab Waist in 3 Steps.
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BINP Tau-Charm Project E.Levichev For the BINP C-Tau team 3 February 2010, KEK, Tsukuba
Outline1. Introduction of Crab Waist collision approach2. Scientific program and specifications3. Optics4. FF and QD05. Polarization insertions6. Energy calibration
Crab Waist in 3 Steps • Large Piwinski’s angle F = tg(q)sz/sx • Vertical beta comparable with overlap area bysx/q • Crab waist transformation y = xy’/(2q) 1. P.Raimondi, 2° SuperB Workshop, March 2006 2. P.Raimondi, D.Shatilov, M.Zobov, physics/0702033 M.Zobov, Tau08, Novosibirsk
Crabbed Waist Scheme Sextupole IP (Anti)sextupole Sextupole strength Equivalent Hamiltonian M.Zobov, Tau08, Novosibirsk
Collisions with and without Crab Sextupoles • Bigger blowup • Sharp lifetime reduction for bunch currents > 8 -10 mA February 2009 Courtesy G. Mazzitelli
Scientific case for the BINP C-tau project ► D-Dbar mixing ► CP violation searches in charm decays ► Rare and forbidden charm decays ► Standard Model tests in leptons decays ► Searches for lepton flavor violation t→mg ► CP/T violation searches in leptons decays ► Production of the polarized anti-nucleons E = 1 GeV (may be with reduced luminosity) Requirements: L > 1034 cm-2 s-1, longitudinal polarization, beam energy range from 1 GeV to 2.5 GeV
Specifications ► Variable energy Ecm= 2 – 5 GeV► Luminosity L = 1÷2×1035 cm-2s-1► Electrons are polarized longitudinally at IP► No energy asymmetry► No beam monochromatization► Energy calibration with medium accuracy is sufficient (Compton backscattering)
Facility key features and principles ► Two rings with a single interaction point► Crab waist collision► SC wigglers to keep the same damping and emittance in the whole energy range (optimal luminosity)► Polarized e- injector and spin control to get the longitudinally polarized electron beam at IP► Wide re-using of the existing structures and facilities tosave the cost
Injection facility exists Tunnel for the linac and the technical straight section of the factory is ready Layout
Main ring: tunnel Ready-built tunnel FF region Technical reg. (RF and injection) Damping wiggler sections
Main accelerator parameters 6 m of the SC wigglers with 20-cm-period are used to control the beam parameters at different energies
Main ring: arc cell FODO but close to the theoretical minimum emittance bx, by
Main ring: injection section bx, by
IR optics bx, by IP Y Section of chroms correction X Section of chroms correction FF telescope Crab Sext End of the telescope L1/2 = 75 m
Luminosity D.Shatilov y=750 um, Θ=50, mrad, σz=1cm, x=10 nm·rad, 0.5% coupling Crab OFF: ξy=0.06 Lbeam=4.94·1031 @ Np=3·1010 Lmax=0.44·1035@ Nb=890 Crab ON: ξy=0.13 Lbeam=2.76·1032 @ Np=7·1010 Lmax=1.05·1035@ Nb=380
IP snake2 snake3 damping wiggler2 damping wiggler1 snake1 Polarization scheme Polarization scheme with 3 snakes (arc=1200+2 damping wigglers in the arc’s middle )
5 snakes 3 snakes 1 snake Polarization vs energy
QD0 SC iron yoke twin aperture magnet Excitation current 1150 A Single aperture 2 cm Gradient 150 T/m
Damping wigglers The damping wigglers keep the damping time tx =30 ms and the horizontal emittance (εx=10 nm) in the energy range 1.0 – 2.5 GeV Wiggler with similar parameters produced by BINP Wiggler field amplitude vs energy
Energy calibration Compton backscattering E calibration (~10-410-5) Na24 (1)=1368.625 keV Na24 (2)=2754.008 keVNa24 (1+2)=4122.633 keV Spectrum edge
Injection facility upgrade • Today: • 21010 e-/pulse (1.5% conversion) 3 108 e+/pulse • 50 Hz = 1.51010 e+/s • Upgrade: • e- current increase ( 3) • Better focusing in positron linac ( 1.5) • Debuncher usage ( 2) • = 1.351011 e+/s • Reserve: electron energy can be increased by 100 MeV ( 1.3)
Summary ►Crab Waist collision seems a very promising idea to enhance a circular colliders luminosity beyond the present value by factor of 10-100 without current increase. ►CW approach was successfully proved experimentally at DAFNE in the end of 2008 ►Novosibirsk SuperCT project is under way. The key issues like IR design, DA optimization, polarization scheme, QD0 design, etc. seem solved successfully ►In 2010 we hope to finish a CDR and in parallel apply for funding to Russian Government.