[en] Experimental research work with the neutron diffraction spectrometers at the MIT Research Reactor concentrated during the past period in two general areas, a study of diamagnetic scattering of neutrons by bismuth and physical effects associated with dynamical diffraction by perfect crystals. The former study showed that the outermost valence (or lattice) electrons contribute dominantly to the field-induced diamagnetism. Fourier transformation of the scattering data provided maps showing the distribution of diamagnetization density throughout the unit cell with pronounced spatial variations. In the latter studies, some of the anomalous effects associated with neutron propagation through diffracting perfect crystals were investigated. These include the very sensitive modification of transport direction within the crystal when the entrance direction is changed slightly or when the neutron energy is changed slightly by applicaton of a modest magnetic field. Additional studies have shown that neutrons propagate through a diffracting crystal with a drift velocity which can be pronouncedly smaller than the usual group velocity

[en] An account is given of the early developments in neutron scattering research continuing from the beginning of 1946 by the Oak Ridge group utilizing the Clinton Pile

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[en] Observations are repoted on the performance of a neutron interferometer using two successive Laue reflections from separated, thick crystal plates. The interferometer makes explicit use of coherence characteristics within the Borrmann fan associated with dynamical diffraction theory. The spatial distribution of the intensity released from the interferometer and the interference effects in the two beams leaving the central focal point have been studied and compared with theoretical prediction

[en] The wave properties of neutrons have been studied and exploited in many areas of physics almost from the time of Chadwick's discovery. Illustrations of these will be provided showing the extreme range of energy and de Broglie wavelength over which they have been observed. Attention will be directed to some of the characteristics associated with wave packet propagation. (author)

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[en] Present interest in the possible existence of isolated magnetic charges has raised questions about the degree of magnetic neutrality in magnetic dipole systems. For the free neutron case, past experiments dealing with the spatial deflection of neutron beams in extended magnetic fields have been analyzed by Ramsey to set an upper limit of 10^-12 for the fractional unbalance of poles separated by the neutron radius. This limit has been lowered by about six orders of magnitude in present experiments of deflection effects in crystals of silicon wherein the anomalously small effective mass of neutrons provides greatly enhanced sensitivity. (orig.)

[en] A search for a novel coupling interaction between the Pendelloesung periodicity which is formed in a diffracting crystal and the Larmor precession of neutrons in a magnetic field has been carried out. This interaction is expected to exhibit a resonant behavior when the two spatial periodicities become matched upon scanning the magnetic field being applied to the crystal. Observations on a diffracting, perfect crystal of silicon with neutrons of wavelength 1 Angstrom show the expected resonant action but some discrepancy between the observed magnitude of the resonance effects remains for interpretation. 16 refs

[en] Up to the present time, perfect crystal interferometers of both two-crystal and three-crystal Laue-case variety have been used to explore the optical characteristics of neutrons of diffracting wavelength. In addition, very recently the classical optical experiments of the diffraction by an absorbing edge, by an absorbing wire and by single and double slit assemblies have been performed for cold neutrons. These experiments show with high precision the validity for matter waves of the standard Fresnel-Kirchhoff approach to diffraction