[en] Experimental and theoretical studies of the neutron-diffraction group at the MIT Research Reactor have concentrated during the past year in areas of neutron interferometry and fundamental diffraction by crystals. Experiments have been performed which demonstrate directly the existence of an anomalously low effective mass for neutrons while being diffracted by a crystal. The experiment consists of applying a transverse force (through the agency of a magnetic field gradient) to the neutrons and observing the change of trajectory. Deflection effects over five orders of magnitude larger than in normal Stern-Gerlach deflection are measured as expected from earlier theoretical analysis. The existence of both positive and negative mass groups is also to be expected and experiments to demonstrate this are in progress. Theoretical analysis has continued on various topics including (a) study of phase perturbations on neutrons caused by the presence of an effective mass in the crystal when a Coriolis force is present, (b) evaluation of limits on possible medium-range interactions between hadrons and (c) the existence of a coupling between the gravitational interaction and other neutron interactions as would be evidenced in interferometry. Preliminary observations are reported on the presence of simultaneous diffraction of neutrons through a crystal and mirror surface reflection