  We discuss a solvable model describing an Anderson like impurity in a BCS
superconductor. The model can be mapped onto an Ising field theory in a
boundary magnetic field, with the Ising fermions being the quasi-particles of
the Bogoliubov transformation in BCS theory. The reflection S-matrix exhibits
Andreev scattering, and the existence of bound states of the quasi-particles
with the impurity lying inside the superconducting gap.
