  The neutron spin is a critical degree of freedom for many precision
measurements using low-energy neutrons. Fundamental symmetries and interactions
can be studied using polarized neutrons. Parity-violation (PV) in the hadronic
weak interaction and the search for exotic forces that depend on the relative
spin and velocity, are two questions of fundamental physics that can be studied
via the neutron spin rotations that arise from the interaction of polarized
cold neutrons and unpolarized matter. The Neutron Spin Rotation (NSR)
collaboration developed a neutron polarimeter, capable of determining neutron
spin rotations of the order of $10^{-7}$ rad per meter of traversed material.
This paper describes two key components of the NSR apparatus, responsible for
the transport and manipulation of the spin of the neutrons before and after the
target region, which is surrounded by magnetic shielding and where residual
magnetic fields need to be below 100 \textmu G. These magnetic field devices,
called input and output coils, provide the magnetic field for adiabatic
transport of the neutron spin in the regions outside the magnetic shielding
while producing a sharp nonadiabatic transition of the neutron spin when
entering/exiting the low-magnetic-field region. In addition, the coils are self
contained, forcing the return magnetic flux into a compact region of space to
minimize fringe fields outside. The design of the input and output coil is
based on the magnetic scalar potential method.
