1 The project of Super-ct-factory with Crab Waist in Novosibirsk E.Levichev Budker Institute of Nuclear Physics, Novosibirsk Tau-08 Satellite Meeting, Novosibirsk September 26-27, 2008

2 Contributors to the report A.BlinovA.Bogomyagkov A.BondarV.Kiselev I.KoopG.Kurkin E.LevichevP.Logachev S.NikitinI.Okunev V.M.PetrovP.Piminov Yu.Pupkov S.Sinyatkin A.Skrinsky D.Shatilov V.Smaluk P.Vobly

3 History ► E = 700 – 2500 MeV ► Round beams L=10 34 cm -2 s -1 ► Monochromatization L~10 32 cm -2 s -1 ► Long. Polarization L~10 34 cm -2 s -1 ► Transverse polarization for precise energy calibration C-tau Conceptual Design Report in Novosibirsk 1995

4 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

5 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 > cm -2 s -1, longitudinal polarization

6 Specifications ► Variable energy E cm = 3 – 4.5 GeV (from J/psi to charm baryons) ► L = 1÷2×10 35 cm -2 s -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)

7 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

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

9 Specification for the FF design Talk by Anton Bogomyagkov

10 FF based on telescope design

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

12 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)

13 Lattice Interaction region betas Dispersion function

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

15 Damping wigglers Field amplitude at 1.5 GeV 4.3 T Period length 0.2 m Total length 8 m Damping integral i 2 at 1.5 GeV 2.76 m -1 Excitation integral i 5 at 1.5 GeV 0.01 m -1 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

16 Luminosity (talk by D.Shatilov)

17 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

18 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

19 Injection facility

20 Injection facility upgrade (talk by P.Logachev) Today: 2  e - /pulse  (1.5% conversion)  3  10 8 e + /pulse  50 Hz = 1.5  e + /s Upgrade: e - current increase (  3) Better focusing in positron linac (  1.5) Debuncher usage (  2) = 1.35  e + /s Reserve: electron energy can be increased by 100 MeV (  1.3)

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

22 Energy calibration (talk by M.Achasov) Compton backscattering E calibration (~10 -4  ) Spectrum edge CBS vs RD for 3 months Sigma = 42 keV

23 Summary C-tau factory with L = 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.