  We present a measurement scheme for observing the Berry phase in a flux
assisted Cooper pair pump - the Cooper pair sluice. In contrast to the recent
experiments, in which the sluice was employed to generate accurate current
through a resistance, we consider a device in a superconducting loop. This
arrangement introduces a connection between the pumped current and the Berry
phase accumulated during the adiabatic pumping cycles. From the adiabaticity
criterion, we derive equations for the maximum pumped current and optimize the
sluice accordingly. These results apply also to the high accuracy pumping which
results in a potential candidate for a metrological current standard. For
measuring the pumped current, an additional Josephson junction is installed
into the superconducting loop. We show in detail that the switching of this
system from superconducting state into normal state as a consequence of an
external current pulse through it may be employed to probe the pumped current.
The experimental realization of our scheme would be the first observation of
the Berry phase in superconducting circuits.
