Super Charm/Tau Factory @ Novosibirsk (project) Super B Factory and Super Charm/Tau Factory synergy:
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1 ICFA Seminar-2008
SLAC, 28-31/10/2008 A.Skrinsky
Super Charm/Tau Factory @ Novosibirsk (project)
THE NOVOSIBIRSK CHARM/TAU FACTORY VEPP-5
(project, up to 5 GeV total) •High luminosity regime
“Round Beams” up to 1⋅1034 cm–2sec–1
•Longitudinally polarized collisions up to 1⋅1033 cm–2sec–1
•High “effective” monochromaticity for δMevent=50 KeV ≥1⋅1032 cm–2sec–1
Charm/Tau Factory (double ring)
R ≈ 50m
with “ROUND BEAMS”
The option implies several important issues: a). Equal - and small! - beta values at Interaction Region
βx = βz = β0 ;
b). Equal horizontal and vertical emittances, excited via quantum fluctuations independently up to the level, required for desired luminosity
εx = εz c). Equal betatron tunes with “zero” coupling
(“no” tunes splitting) Qx = Qz ;
d). Small positive (for e+e-) tune shifts above half-integer in Qx,z (for single Interaction per turn);
e). Low (tunable) synchrotron frequency Qs.
Highest Luminosity option
Items a), b) and c) lead to the conservation of angular momentum in transversal motion, thus converting this motion to “one-dimensional” one, with less beam-beam resonances, which can cause beam blow-up and/or degrade its lifetime. Items d)(close to half-integer) and e)(low synchrotron frequency) proved in computer simulations to be useful in rising the maximal beam- beam tune shift ξmax, which does not damage luminosity. We hope to raise this value, at least, up to 0.1 .
The additional useful effect arises due to the simple fact, that the beam-beam focusing for given counting bunch density is 2 times lower for round beams than for smaller dimension of flat beam.
e-e- e+ e+
1 m 1 m
Final Focus solenoids (~15 T )
13 Tesla – reached at VEPP-2000!
The new collider VEPP-2000, based on round beams approach, for energy range from pion threshold up to 2 GeV was constructed and now is in commissioning stage. First luminosity (~1·1031cm-2s-1 in 1+1 bunch mode, 2 IP) at φ meson energy was successfully achieved. Two detectors are in final preparation for data taking.
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.81 . 1029
1 . 1030
1 . 1031
1 . 1032
1 . 1033
Center of Mass Energy, GeV
s-1 VEPP-2000 Luminosity
Polarization/damping asymmetric wigglers
- independent signs - for independent e+ and e- helicity control!
Monochromatization (the idea)
Higher energy Lower energy
Lower energy Higher energy
dispersion_E monok δ
The project of Super Carm/Tau factory with Crab Waist in Novosibirsk
Contributors to the report
Motivation to restart:
► Exciting results of B-factories
► Invention of the crab waist collision scheme (P.Raimondi, March 2006; demonstration: DAFNE, 2007) - hope for even higher luminosity
Super B Factory needs data of Super Charm/Tau Factory class!
► D-Dbar mixing ► CP violation searches in charm decays ► Rare and forbidden charm decays ► Standard Model tests in τ leptons decays ► Searches for lepton flavor violation τ μγ ► CP/T violation searches in τ leptons decays
Requirements: L>1035 cm-2 s-1, longitudinal polarization
► Variable energy Ecm= 2 – 4.5 GeV (up to charmed barions)
► L = 1÷2×1035 cm-2s-1 ► At least one beam (e-) should be polarized longitudinally
► No energy asymmetry is needed (B Factories!) ► No beam monochromatization is needed
► Energy calibration with medium accuracy (Compton backscattering)
Injection facility is in operation
Tunnel for the linac and the technical straight section of the factory is ready
100m long hall is ready
181*1035Luminosity, cm-2s-1 0.13Tune shift ξy
0.8Spot length, mm
34Crossing angle, mrad
1.4Beam current, A
7*1010Particles per bunch
300Number of bunches
800Rings perimeter, m
2Beam energy, GeV Main design parameters
L c Π
4 π⋅ σx0⋅ σy0⋅ ⋅
2 2⋅ π⋅
⋅ Nbunches⋅ N1 2
4 ⋅ βx0
4 ⋅ kyx
2 ⋅ σz⋅
► Two rings with a single interaction point.
Facility key features and principles
► Crab waist collision → extreme importance of the FF design (large collision angle + very small r-emittance very short Interaction-Spot + proper sextupoles:
all beam spread energies meet in the same spot) ► Wigglers to keep the same damping and emittance in the whole energy range (optimal luminosity). ► Modified FODO ring cell to obtain very low x-emittance.
► Polarized e- injector and spin gymnastics based on the Central Arc solution to get the longitudinally polarized electron beam at IP. ► Deep adaptation of the existing injection complex, construction facilities (tunnels, halls, etc.) and elements (wigglers, etc.) for cost effectiveness.
Many features/problems similar to the European SuperB.
0.01 m-1 Excitation integral i5 at 1.5 GeV
2.76 m-1Damping integral i2 at 1.5 GeV 8 mTotal length 0.2 mPeriod length 4.3 TField amplitude at 1.5 GeV
The damping wigglers keep the damping time Tau_x =30 ms and the horizontal emittance (10 nm) in the energy range 1.5 – 2.5 GeV
Wiggler field amplitude vs energy
Wiggler with similar parameters produced by BINP
Luminosity (talk by D.Shatilov)
Longitudinal polarization at IP
← Schematic view of the longitudinally polarized e- at IP
Degree of the LP at IP → as a function of the beam energy
Polarized electrons source Polarized electron source produced by BINP for AmPS
• Beam polarization 90 % • Cathode voltage 100 kV • Photocathode type Strained InGaAsP • Laser type Ti – Sapphire • Light wavelength 700 – 850 nm • Laser power in a pulse 200 W • Pulse duration 2.1 μs • Repetition rate 1 Hz • Maximum current from a gun 150 mA • Operational current 15 – 20 mA • Photocathode lifetime 190 – 560 hours
SCT location FF region
Technical reg. (RF and injection)
Damping wiggler sections
Hall is ready
Damping ring To VEPP-2000
to VEPP-4 and Charm/Tau
300 MeV linac
LINACS to GENERATE e+ and ACCELERATE e+ and e- to 500 MeV.
STORAGE RING/COOLER for e+, e-
Injection facility upgrade • Today: • 2×1010 e-/pulse → (1.5% conversion) → 3 ×108 e+/pulse • × 50 Hz = 1.5×1010 e+/sec
we need 3*10-25*1*1035=3*1010
• Upgrade: • Debuncher usage (× 2) (part of the initial project) • e- current increase (× 3) • Better focusing in positron linac (× 1.5)
• Reserve: electron energy can be increased by 100 MeV (× 1.3)
2.5 GeV linac ► Using the same accelerating structure as for the existing injection facility ► 13 accelerator modules (200 MeV, 16 m) each of 4 accelerator structures.
Totally 208 m ► In a 1-m straight section between the accelerator structures there are two
quadrupoles, BPM and vacuum valve ► Four accelerator structures (one module) are fed by one 5045 klystron
(SLAC) ► Repetition frequency is 50 Hz
The tunnel is ready.