Visibility evaluation of a neutron grating interferometer operated with a polychromatic thermal neutron beam.

Visibility evaluation of neutron gratings for a polychromatic thermal neutron beam was performed for a neutron grating interferometer. Four sets of neutron gratings designed for neutron wavelengths of 2.0Å, 2.7Å, 3.5Å, and 4.4Å were fabricated and tested to find the neutron grating interferometer setup with maximum visibility. The measurements were carried out at the thermal neutron beamline of the Ex-core Neutron irradiation Facility (ENF) of the High-flux Advanced Neutron Application Reactor. The maximum visibility was obtained at the neutron grating set designed for a neutron wavelength of 2.7Å among the four sets, and the visibility was 9.7%. The experimental data can be the basis for an optimization of the neutron grating interferometer at the thermal neutron beamline, and can be further optimized for neutron dark-field imaging with high spatial resolution and a shorter data acquisition time. [ABSTRACT FROM AUTHOR]