1. Polarization issues in SuperB-Factories I.A.Koop, BINP, Novosibirsk, Russia Frascati Workshop, March 16-18, 2006

2. Polarization Scenario Frascati Workshop, March 16-18, 2006 Selfpolarization via Sokolov-Ternov mechanism in damping rings. For e + this is the only way. Rotate spin alternatively by +90 0 or –90 0 around z- axis in the transport channel with subsequent beam and spin rotation in the horizontal plane to get finally the longitudinal polarization at IP. Option: accelerate longitudinally polarized electrons from a gun (we need ~10 6 polarized electrons/bunch).

3. Polarization Scenario (Cont’d) Frascati Workshop, March 16-18, 2006 45 0 + 45 0 Spin Rotator (two solenoids and few quads in between) Spin is vertical in DR. Being extracted becomes horizontal in transport line, then longitudinal at IP IP Restored spin (directed vertically) by similar spin-rotator before re-injection back into the DR X

4. Frascati Workshop, March 16-18, 2006 Selfpolarization in Damping Rings with Asymmetric Wigglers Asymmetric Bending Field in Wigglers! B + >|B - | B + =1.542 T B - =-0.514 T B + l + =|B - |l -

5. Frascati Workshop, March 16-18, 2006 Polarization Degree

6. Frascati Workshop, March 16-18, 2006 Polarization Time

7. Frascati Workshop, March 16-18, 2006 Comparison with a Beam Lifetime

8. 90 0 Spin Rotator for Transport Channel 45 0 Two 45 0 solenoids Decoupling FODO Optics: T x =-T y

9. Frascati Workshop, March 16-18, 2006 Decoupling Insertion between two Solenoids

10. Frascati Workshop, March 16-18, 2006 Multi-layered Damping Ring In case of non-flat damping ring the vertical bends may contribute to the beam depolarization. This should be taken into account. 3-layered ring (3 ? to 6 ?): Vertical bends

11. Frascati Workshop, March 16-18, 2006 Spin Transparency Condition Transparency condition: θ1, θ2 –entrance & exit azimuths of the insertion, θ=z/R The spin transparency could be fulfilled more or less easily!

12. Frascati Workshop, March 16-18, 2006 Polarization Measurements Compton scattering of circular polarized light on longitudinally polarized electrons – 100% asymmetry! Places where this can be done: a special vertical wiggle in a damping ring. There polarization has the longitudinal component. Another place - near IP, where spin is directed also longitudinally.

13. Conclusions Radiative polarization with a high degree ζ> 50% is achievable for both beams. Asymmetric polarizing wigglers are needed, say with B + =1.542 T,, B - =-0.514 T. The build up time in the order of τ p =1 hour is feasible This number is comparable with the beam life time value. But Toushek lifetime, seems, is much lower! Injection of already polarized electrons from a gun is welcomed. This will improve essentially the polarization degree and minimize the start up time for experiments with polarized beams. Also it would help to fight against Toushek losses. Should be paid some attention to spin transparency in multi-layered damping ring and/or in IR.