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The project of Super-ct-factory with Crab Waist in Novosibirsk

E.Levichev

Budker Institute of Nuclear Physics, Novosibirsk

Tau-08 Satellite Meeting, NovosibirskSeptember 26-27, 2008

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Contributors to the report

A.Blinov A.Bogomyagkov

A.Bondar V.Kiselev

I.Koop G.Kurkin

E.Levichev P.Logachev

S.Nikitin I.Okunev

V.M.Petrov P.Piminov

Yu.PupkovS.SinyatkinA.Skrinsky

D.ShatilovV.SmalukP.Vobly

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History

► E = 700 – 2500 MeV► Round beams L=1034 cm-2s-1

► Monochromatization L~1032 cm-

2s-1

► Long. Polarization L~1034 cm-2s-

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► Transverse polarization for precise energy calibration

C-tau Conceptual Design Report in

Novosibirsk

1995

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Motivation of restart

► Invention of the crab waist collision scheme (P.Raimondi, March 2006; demonstration: DAFNE, 2007)

► Exciting results of B-factories

► Hint of financial support from Russian Government

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Scientific case (talk by V.Druzhinin)

► 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► CP/T violation searches in t leptons decays

Requirements: L > 1034 cm-2 s-1, longitudinal polarization

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Specifications

► Variable energy Ecm= 3 – 4.5 GeV (from J/psi to charm baryons)► L = 1÷2×1035 cm-2s-1

► At least one beam (e-) should be polarized longitudinally► No energy asymmetry is needed► No beam monochromatization is needed► Energy calibration with medium accuracy (Compton backscattering)

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Facility key features and principles► Two rings with a single interaction point► Crab waist collision extreme importance of the FF design ► Polarized e- injector and spin gymnastics based on the Central Arc solution to get the longitudinally polarized electron beam at IP► Wigglers to keep the same damping and emittance in the whole energy range (optimal luminosity)► Modified FODO cell to obtain low emittance► A wide 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

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Layout

Injection facility exists

Tunnel for the linac and the technical straight section of the factory is ready

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Specification for the FF designTalk by Anton Bogomyagkov

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FF based on telescope design

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SCT locationFF region

Technical reg. (RF and injection)

Damping wiggler sections

Hall is ready

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Main accelerator parameters

8 m of the SC wigglers with 20-cm-period are used to control the beam parameters at different energies (by Pavel Piminov)

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Lattice

Interaction region betas

Dispersion function

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Lattice

Arc cell (FODO but close to the theoretical minimum emittance)

Technological section

Betatron tune bandwidth 1%

Transverse DA is a crucial problem !!!

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Damping wigglers

Field amplitude at 1.5 GeV 4.3 T

Period length 0.2 m

Total length 8 m

Damping integral i2 at 1.5 GeV 2.76 m-1

Excitation integral i5 at 1.5 GeV 0.01 m-1

The damping wigglers keep the damping time Tau_x =30 ms and thehorizontal emittance (10 nm) in the energy range 1.5 – 2.5 GeV

Wiggler field amplitude vs energy

Wiggler with similar parameters produced by BINP

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Luminosity (talk by D.Shatilov)

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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

Talk by Sergey Nikitin

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Polarized electrons source (talk by I.Koop)

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 s• Repetition rate 1 Hz• Maximum current from a gun 150 mA• Operational current 15 – 20 mA• Photocathode lifetime 190 – 560 hours

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Injection facility

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Injection facility upgrade (talk by P.Logachev)

• 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)

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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

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Energy calibration (talk by M.Achasov)

Compton backscattering Ecalibration (~10-410-5)

Spectrum edge CBS vs RD for 3 monthsSigma = 42 keV

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Summary• C-tau factory with L = 1035 cm-2 s-1 seems to be an

extremely attractive facility for HEP experiments

• Crab-waist approach allows us to obtain such luminosity with achievable machine parameters: required beam intensity, low emittance, injection efficiency, polarization features have been already obtained in B- and Phi-factories, light sources, etc.

• We are in the beginning now and there are many things have to be done (further optimization of the FF design, the DA optimization, Touschek lifetime increase, etc.). But at the same time we have an advantage-ground to start the project: injection facility is under commissioning, tunnels for linac and injection lines are ready, a lot of the facility solutions are based on existing wares and technologies.