1. The project of Super-ct-factory with Crab Waist in Novosibirsk
E.Levichev
Budker Institute of Nuclear Physics, Novosibirsk
Japan-Italy Collaboration Meeting
“Crab Factories”, Frascati, December 10, 2008

2. 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.Pupkov
S.Sinyatkin
A.Skrinsky
D.Shatilov
V.Smaluk
P.Vobly

3. C-tau Conceptual Design Report in Novosibirsk
History
C-tau Conceptual Design Report in Novosibirsk
► E = 700 – 2500 MeV ► Round beams L=1034 cm-2s-1 ► Monochromatization L~1032 cm-2s-1 ► Long. Polarization L~1034 cm-2s-1 ► Transverse polarization for precise energy calibration
1995

4. Motivation of restart
► Invention of the crab waist collision scheme (P.Raimondi, March 2006; demonstration: DAFNE, 2007) ► Exciting results of B-factories ► Russian Government is ready to support ambitious modern projects in fundamental science

5. Processes at tau-charm factory Ds D


6. Tau-charm physics Charm Charmonia Spectroscopy Spectroscopy, BFs
(Semi)leptonic decays
Rare decays
Mixing
CP violaton …
Charmonia
Spectroscopy, BFs
Light hadron spectroscopy
J/ rare decays …
Tau
Spectral functions, BFs
Lorentz structure
CP violation
LFV decays …
Charm baryons
BFs
Semileptonic decays …
Requirements: L > 1034 cm-2 s-1, longitudinal polarization

7. 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)

8. 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 longitudinally polarized electron beam at IP ► Wigglers to keep the same damping and emittance in the whole energy range (optimal luminosity) ► Low emittance arc cell ► A wide adaptation of the existing injection complex, construction facilities (tunnels, halls, etc.) and elements (wigglers, etc.) for cost effectiveness Both CT project in Novosibirsk and SuperB in Tor-Vergata exploit the Crab waist approach  similar problems and solutions  good background for collaboration

9. Layout Injection facility exists
Tunnel for the linac and the technical straight section of the factory is ready

10. Specification for the FF design

11. FF based on telescope design

12. Final focus trajectories

13. Betatron frequency bandwidth

14. Main accelerator parameters
8 m of the SC wigglers with 20-cm-period are used to control the beam parameters at different energies

15. Lattice
Interaction region betas
Dispersion function

16. Lattice Technological section
Arc cell (FODO but close to the theoretical minimum emittance) 
Transverse DA is a crucial problem !!!
Betatron tune bandwidth 1%

17. Damping wigglers
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
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
Wiggler with similar parameters produced by BINP
Wiggler field amplitude vs energy

18. Luminosity

19. 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

20. Integration of polarization insertion
into the current variant of the Super C-Tau magnetic structure

21. Polarized electrons source
Beam polarization %
Polarization lifetime – 4500 s
Cathode voltage (pulsed) kV
Photocathode type Strained InGaAsP
Laser type Ti – Sapphire
Light wavelength – 850 nm
Laser energy in a pulse mkJ
Pulse duration ns
Repetition rate Hz
Number of electrons/pulse *10^10
Photocathode quantum efficiency 1%
Photocathode recesiation time
(depends on laser power) – 560 hours

22. Injection facility

23. Positron production High positron yield Y = 0.1 e+/e-/GeV
Positron conversion target
Positron production section
High positron yield
Y = 0.1 e+/e-/GeV
10 T pulsed magnet positron concentrator

24. Injection facility upgrade
Today:
21010 e-/pulse  (1.5% conversion)  3 108 e+/pulse
 50 Hz = 1.51010 e+/s
Upgrade:
e- current increase ( 3)
Better focusing in positron linac ( 1.5)
Debuncher usage ( 2)
= 1.351011 e+/s
Reserve: electron energy can be increased by 100 MeV ( 1.3)

25. 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

26. Energy calibration Compton backscattering E calibration (~10-410-5)
CBS vs RD for 3 months
Sigma = 42 keV
Spectrum edge

27. SCT location FF region Technical reg. (RF and injection)
Damping wiggler sections
Hall is ready

28. 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. First test of the crab-waist approach was successfully passed in Frascati
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.