  A magnetically trapped atom experiences an adiabatic geometric (Berry's)
phase due to changing field direction. We investigate theoretically such an
Aharonov-Bohm-like geometric phase for atoms adiabatically moving inside a
storage ring as demonstrated in several recent experiments. Our result shows
that this phase shift is easily observable in a closed loop interference
experiment, and thus the shift has to be accounted for in the proposed inertial
sensing applications. The spread in phase shift due to the atom transverse
distribution is quantified through numerical simulations.
