  We demonstrate the time reversal Aharonov-Casher (AC) effect in small arrays
of mesoscopic semiconductor rings. By using an electrostatic gate we can
control the spin precession rate and follow the AC phase over several
interference periods. We show that we control the precession rate in two
different gate voltage ranges; in the lower range the gate voltage dependence
is strong and linear and in the higher range the dependence in almost an order
of magnitude weaker. We also see the second harmonic of the AC interference,
oscillating with half the period. We finally map the AC phase to the spin-orbit
interaction parameter alpha and find it is consistent with Shubnikov-de Haas
analysis.
