Polarization at the SuperB Factory J Seeman SLAC

Polarization at the Super-B Factory J. Seeman SLAC IRC Meeting November 13, 2007

Polarization studies for Super-B • • Contributions from: I. Koop (BINP) S. Nikitin (BINP) M. Preger (INFN Frascati) P. Raimondi (INFN Frascati) J. Seeman (SLAC) U. Wienands (SLAC)

Why not let the beam self-polarize? • Polarization time: SBF beam lifetime =~ 5 minutes Inject polarized electrons from the linac

Ring Layout (from F. Forti) SPARX • Super. B Ring (about 1800 m) Super. B Injector (about 400 m) Roman Villa 100 m Super. B Main Building

Example of Injected Polarized Electrons Polarization Components from the SLC at SLAC Polarized Photo-Gun 120 Hz, 87% 2 x 5 x 10^10/pulse Spin manipulators SLC IP Located at the Stanford Linear Accelerator Center Polarization equipment ready for reuse!

IP Spin Rotation •

Spin Transport Issues • • • Spin rotation x-y coupling Spin chromaticity Depolarizing resonances IP symmetry Beam-beam forces

“Foot print” shape preferred

Alternative #1 of IP Spin Rotator

Alternative #2 of IP Spin Rotator Derbenev, Kondratenko, Skrinsky, 1977 Snake IP Snake rotates spin by 1800 around z-axis In arcs spin lies in the horizontal plane At IP the spin is directed longitudinally (exactly!)

Polarization times • LER: – Best energies: 3. 83 Ge. V, 4. 10 Ge. V to avoid resonances – Polarization times: • 10800 sec with antisymmetric IP horiz. bends • 3300 sec with symmetrical IP horiz. bends • HER: – Best energies: 6. 92 Ge. V, 7. 18 Ge. V to avoid resonances – Polarization time: • 2800 sec with antisymmetric IP horiz. bends

Polarization Conclusions • Polarization of one beam is included in Super-B. – Either energy beam could be the polarized one. – The LER would be less expensive. • Long polarization times and short beam lifetimes indicates a need to inject polarized electrons in the vertical plane. • There are several possible IP spin rotators. – Solenoids look better at present. • Expected longitudinal polarization at the IP of about 87%(inj) x 97%(ring)=85%(effective).