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Polarization scheme with the odd number of Siberian Snakes. I.A.Koop BINP, 630090 Novosibirsk, Russia Tau-2008 satellite meeting Novosibirsk 26-27 . 09 .200 8. Outline. Polarization scheme based on concept of use of an odd number of snakes – the solution for very wide energy range
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Polarization scheme with the odd number of Siberian Snakes I.A.Koop BINP, 630090 Novosibirsk, Russia Tau-2008 satellite meeting Novosibirsk26-27.09.2008
Outline • Polarization scheme based on concept of use of an odd number of snakes – the solution for very wide energy range • Spin transparency and the snake optics • Calculation of spin relaxation time in presence of damping wigglers (tau=30 ms) – analytical approach • Polarization degree estimations • Conclusion
Spin orbit in presence of Siberian Snake Derbenev, Kondratenko, Skrinsky, 1977 Snake rotates spin by 1800 around z-axis Snake In arcs spin lies in the horizontal plane At IP spin is directed longitudinally (exactly!) IP With a partial snake at magic energy spin is directed also longitudinally at IP and similarly at the snake’s location
Polarization scheme with 3 snakes (arc=1200+2 damping wigglers in the arc’s middle ) IP snake2 snake3 damping wiggler2 damping wiggler1 snake1
1800 Spin Rotator (Siberian Snake) Decoupling condition: Tx=-Ty Litvinenko, Zholentz, 1980 All quads are not skewed! Each of two solenoids provides 900 spin rotation. Needed field integral 13 T*m at E=2.5 GeV
Depolarization time in presenceof snakes Placing damping wigglers in minimum |d| one would minimize depolarizing effects Betatron oscillations could increase |d|. Spin transparency is desirable!
Self-polarization in presence of snakes Asymmetric wigglers contribute to self-polarization
Spin relaxation time, 1 snake Wigglers localized at optimum azimuth Wigglers distributed uniformly along a ring
Spin relaxation time, 3 snakes Wigglers localized at optimum azimuth Wigglers distributed uniformly along a ring
Spin relaxation time, 5 snakes Wigglers localized at optimum azimuth Wigglers distributed uniformly along a ring
Polarization degree, 1 snake Damping wigglers placed at optimum azimuth
Polarization degree, 3 snakes Damping wigglers placed at optimum azimuth
Polarization degree, 5 snakes Damping wigglers placed at optimum azimuth
5 snakes 3 snakes 1 snake Polarization degree overview
Conclusion • 1 snake provides up to 80% of the longitudinal polarization at E < 1.5 GeV • 3 snakes could provide sufficiently high polarization degree, about 70-80% in the energy range 1 < E < 2 GeV and about 50% at 2.5 GeV. Probably OK? • 5 snakes cover the full energy range: 1 < E < 2.5 GeV. P=80% almost everywhere.