OBSERVATION OF THE SCALAR AHARONOV-BOHM EFFECT BY NEUTRON INTERFEROMETRY

A phase shift for de Broglie waves due to the action of a scalar poten tial in an otherwise field-free (i.e., force-free) region of space is known as the scalar Aharonov-Bohm (AB) effect. Unlike the more familia r AB effect due to the magnetic vector potential, the scalar effect ha s hitherto remained unverified due, presumably, to technical difficult ies in electron interferometry. We have performed an analogous interfe rometric experiment with thermal neutrons subject to pulsed magnetic f ields. The observations were carried out at the University of Missouri Research Reactor using a skew-symmetric perfect-silicon-crystal neutr on interferometer. The expected phase shifts have been observed to a h igh degree of accuracy. A detailed description of the experiment and i ts interpretation is given in this paper.