多層膜における中性子の光学的性質

Abstract

Optical properties of neutrons for multibilayer films, which can be used for neutron monochromator, neutron supermirror, and neutron polarizer, have been investigated using time-of-flight technique. The experimental diffraction patterns were well fitted with those calculated after the plane wave Schrödinger equation for one dimensional periodic square potentials. The even-order Bragg reflections for the periodic potential, which should not be present according to the kinematical theory, were observed both in the experimental results and the calculated ones after the plane wave Schrödinger equation. The number of the bilayers necessary to gain 100% reflectivity for the main Bragg reflection is found 5-6 pairs for the thickness of 110Å of the Ni-Mn multibilayer, but much more layers are required for smaller thickness of the layers.The critical angle of total reflection for the Ni-Mn supermirror (52 bilayers) was improved up to twice as much as that of a simple Ni mirror. The magnetized Fe-Al multilayers with the thickness of 116Å (6 pairs) proved to afford 95% polarizability and 63% reflectivity, at the main peak of Bragg reflection.