Super Charm/Tau Factory @ Novosibirsk (project) Super B Factory and Super Charm/Tau Factory synergy:

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Transcript of Super Charm/Tau Factory @ Novosibirsk (project) Super B Factory and Super Charm/Tau Factory synergy:

  • 1 ICFA Seminar-2008

    SLAC, 28-31/10/2008 A.Skrinsky

    Super Charm/Tau Factory @ Novosibirsk (project)

  • 2

  • 3

    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

  • 4

    Injection complex

    VEPP-4M

    VEPP-3

    Charm/Tau Factory (double ring)

    R≈100m

    R ≈ 50m

    Synchrotron

    VEPP-2000

    BEP

  • 5

    100 m

    3 m

    e+e-

    General scheme

    RF RF

    Damping/excitation/polarization wigglers

  • 6

    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

  • 7

    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.

  • 8

    e-e- e+ e+

    I P

    1 m 1 m

    Final Focus solenoids (~15 T )

    13 Tesla – reached at VEPP-2000!

  • 9

    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

    L, c

    m -2

    s-1 VEPP-2000 Luminosity

  • 10

    100 m

    3 m

    e+e-

    RF RF

    Polarization/damping asymmetric wigglers

    Longitudinal Polarization

    π/2 solenoids

    - independent signs - for independent e+ and e- helicity control!

  • 11

    Monochromatization (the idea)

    e- e+

    Higher energy Lower energy

    Lower energy Higher energy

    Since 1974

    cetanemit_v

    dispersion_E monok δ

    Δ =Improvement:

  • 12

    The project of Super Carm/Tau factory with Crab Waist in Novosibirsk

    Current stage:

  • 13

    Contributors to the report

    S.Sinyatkin A.Skrinsky

    P.Vobly

    D.Shatilov V.Smaluk

    Yu.PupkovP.Piminov V.M.PetrovI.Okunev

    S.NikitinP.Logachev E.LevichevG.Kurkin

    V.Druzhhinin I.Koop

    A.Bondar V.Kiselev

    A.BogomyagkovA.Blinov

  • 14

    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!

  • 15

    Scientific case

    ► 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

  • 16

    Specifications

    ► 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)

  • 17

    Layout

    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

    0.8βz, mm

    20βx, mm

    34Crossing angle, mrad

    1%Coupling εy/εx

    10εx, nm*rad

    10σz, mm

    0.27σy, mcm

    14σx, mcm

    1.4Beam current, A

    7*1010Particles per bunch

    300Number of bunches

    800Rings perimeter, m

    2Beam energy, GeV Main design parameters

    L c Π

    Nbunches⋅ N1

    2

    4 π⋅ σx0⋅ σy0⋅ ⋅

    σzspot σz

    ⋅:=

    L 1

    2 2⋅ π⋅

    c Π

    ⋅ Nbunches⋅ N1 2

    ⋅ 1

    θcross

    1

    2 εx

    3

    4 ⋅ βx0

    1

    4 ⋅ kyx

    1

    2 ⋅ σz⋅

    ⋅:=

  • 19

    ► 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.

  • 20

    Damping wigglers

    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

  • 21

    Luminosity (talk by D.Shatilov)

  • 22

    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

  • 23

    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

  • 24

    SCT location FF region

    Technical reg. (RF and injection)

    Damping wiggler sections

    Hall is ready

  • 25

    POSITRON SOURCE

    debuncher

    Damping ring To VEPP-2000

    electron gun

    subharmonic target

    photo-gunlinac

    to VEPP-4 and Charm/Tau

    300 MeV linac

  • 26

    Injection facility

  • 27

    LINACS to GENERATE e+ and ACCELERATE e+ and e- to 500 MeV.

  • 28

    STORAGE RING/COOLER for e+, e-

  • 29

    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)

    1.35×1011 e+/sec

    • Reserve: electron energy can be increased by 100 MeV (× 1.3)

  • 30

    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.