Analysis and testing of the divergence and alignment indicator using the Penn State neutron radiography beam.

The divergence and alignment indicator (DAI) was developed to test the alignment of the imaging plane in a neutron beam and to determine the divergence angle of the beam. The construction of the device was intentionally kept simple to allow ease of implementation. The DAI consists of an aluminum plate and rods, and cadmium wire for contrast. The device was tested in the Pennsylvania State University Breazeale Nuclear Reactor neutron radiography beam. Three basic cases (aligned, aligned in only one direction, and completely misaligned), were used to determine that the derived equations for calculating the beam divergence were correct for each case. During the use of a newly fabricated DAI device, it was discovered that the most prominent weakness of the DAI is the precision necessary in the construction. For example, the top of the plate must be precisely flat. Otherwise, the minor differences in height will lead to large discrepancies in the data.