Search for effects on neutron transmission due to multiple reflection by glass capillary walls

We have performed two separate experiments using glass capillary fibers to transport (1) polarized neutrons, and (2) cold neutrons with the fiber at high temperature. The same type of capillary fibers has been used to construct neutron and x-ray focusing lenses. The purpose was to observe whether multiple glancing angle collisions during transport could change either the polarizations or the transmission and exit divergence. In the first case, polarized 0.235 nm neutrons were transmitted through a bent glass capillary fiber, and the spin states of the emergent neutrons were measured. In the second experiment, 0.5 nm neutrons were passed through a glass capillary fiber heated to 200 degrees Celsius, and transmission and divergence were compared to the values at room temperature. The negative result for the first experiment indicates that capillary fibers can be used to transmit polarized neutrons. The heating experiment demonstrated that thermal vibrations of the capillary walls or collisions with heated air molecules did not significantly affect fiber properties; however, some mechanical shifting took place at high temperature.