Dp. Barber et al., A CANONICAL 8-DIMENSIONAL FORMALISM FOR CLASSICAL SPIN-ORBIT MOTION IN STORAGE-RINGS .2. NORMAL FORMS AND THE N-AXIS, Zeitschrift fur Physik. C, Particles and fields, 64(1), 1994, pp. 143-167
The two real canonical spin variables alpha and beta introduced in an
earlier paper to describe spin motion in storage rings [1] are combine
d with the six canonical variables of coupled synchro-betatron motion
to form a system of eight canonical spin-orbit variables in which spin
and orbital motion are treated on the same level. In these variables
one turn maps are origin preserving and the usual techniques of canini
cal perturbation theory can be applied. By writing the Hamiltonian in
normal form the spin detuning terms as well as the so called n-axis, t
he semiclassical spin axis which is needed in the theory of radiative
polarization, can be constructed. The equations derived are valid for
arbitrary particle velocity (below and above transition energy).