Maximum-likelihood deconvolution of TREAT hodoscope scan data

Maximum-likelihood deconvolution increases the spatial resolution of hodoscope scan data. The fast-neutron hodoscope at the Transient Reactor Test Facility (TREAT) is used in a horizontal scan mode before and after test fuel relocation experiments. For a scan, the hodoscope collimator is stepped in small increments, and fuel counts are measured at each step for all 360 channels. Each channel corresponds to one slot in the collimator and an associated neutron counter. The scan is performed at very low reactor power, so no test fuel relocation occurs. The scan mode advantage is a higher test fuel spatial resolution than that of a stationary collimator. Even so, scan-mode, horizontal resolution of each channel is much larger than the width of the channel incremental scan step projected at the test fuel. Because of the point-source response function of a collimator channel, each point of the fuel source is counted at several adjacent steps in the scan.