Neutron Pinhole Characterization and Analysis for Three-Dimensional As-Built Model Reconstruction

The neutron pinhole array, used to collect neutron burn, X-ray, and more recently, gamma emission images, has been in use at the National Ignition Facility since 2011. Since then, there has been the ever-continuing challenge of meeting tighter alignment and resolution requirements. Part of that challenge is being able to accurately characterize the as-built variances from the nominal design associated with the manufacturing and assembly of the pinhole array. To overcome this specific challenge, multiple processes are taken to obtain high-precision profiles of the various features of each pinhole array. This paper highlights the processes used as well as the steps taken to compile the significant amount of data and turn it into an accurate as-built reconstructed model of the NIS1-U-assembled pinhole array.