History: Polarization

As the beam travels around the accellerator, the spin of the polarized electrons will precess in a plane parallel to the ground. The longitudinal polarization of the electrons are dependent on the total precession, which can be calculated. The final angle of the electrons can be found using:

Where E_l is the (single) linac energy (2E_l is energy/pass), n is the number of passes, m is the electron mass. a is the ratio of injector energy to 2E_l (=0.1125). b is is a constant dependent on the extractor arc. For Hall A a_A = -1/2.4, for Hall B a_B = 0, and for Hall C a_C = 1/2.4.

Also see:
[http://www.jlab.org/~moller/spin_dance.html|Hall A Moller Spin Dance Page]

Phys. Rev. Spec. Top. - Accel. & Beams, Vol 7, 042802 (2004)