The high-energy beam line (4) which delivers the proton beam from the main
stage cyclotron to the target area is split into two parts: 1) Beam
line 3 (BL3) which is between the main stage cyclotron and the 
bend, and 2) Beam line 5 (BL5) from the 
bend to the beam swinger
area. Both BL3 and BL5 include a precession solenoid and a beam line
polarimeter.
Of necessity, the beam
must pass through the cyclotron with a polarization normal to the plane
defined by BL3 and BL5, which is parallel to the fields in the cyclotron.
The combination of the precession solenoids and the 
bend make it
possible to precess the beam polarization to any of the three states:
normal, sideways, and longitudinal (N, S, and L).
The precession solenoids are capable rotating the spin of the proton in the
plane transverse to the beam line. The 
bend will precess any
polarization component in the plane defined by BL3 and BL5 according to the
Thomas precession formula:
where 
is the proton mass, and 
is the proton magnetic moment
and is equal to 
(
nuclear magneton 
). At 200 MeV the
precession can be given, to a very good approximation, as
. So, any in-plane polarization
component will be rotated by 
.