Angular response of perforated silicon diode high efficiency neutron detectors

Perforated silicon diodes with two different etched patterns were tested for neutron counting efficiency and angular response. The etched patterns consisted of circular holes on a square lattice or continuous sinusoidal waves. Normal incident neutron counting efficiencies were determined to be 21% and 35% for circular hole and sinusoidal devices, respectively. A nonuniform angular response was identified for the circular hole perforated devices. For the circular hole patterns, a reduction in efficiency appeared at azimuthal angles near 0deg and 90deg, each referenced at a 90deg polar angle about the normal axis. The nonuniform angular response is due to neutron streaming paths through the square lattice. The sinusoidal device angular response was uniform and matched well to that of a standard simple planar device.