An energy resolved neutron imaging detector based on boron doped nMCP coupled with a time stamping optical camera

Abstract

Energy resolved neutron imaging has developed rapidly due to its advantage on testing the inner structure of crystal samples. Neutron detector is one of the key components to determine the imaging results quality. The neutron sensitive microchannel plate (nMCP) has been widely used in energy resolved neutron imaging experiments because of the high spatial and timing resolution. However, the ability to adjust field-of-view (FOV) and spatial resolution has not been realized in the nMCP detector, which is an attractive capability in energy resolved neutron imaging experiments. In this paper, an energy resolved neutron imaging detector was developed by coupling nMCP with a time stamping camera. The neutrons were absorbed by nMCP and converted into light through a phosphor screen. Then the light was focused on the camera by optical lens. A data algorithm was designed to improve the data quality. By changing the magnification of the optical lens, large FOV (46mm diameter) and high spatial resolution (26 μm) were realized in the experiments at CSNS beamline 20. The energy resolved ability was demonstrated by a Bragg-edge transmission imaging experiment for aluminum and stainless-steel samples. The performance of this detector makes it a promising candidate used in energy resolved neutron imaging.

Performance optimization of the neutron-sensitive image intensifier used in neutron imaging

“…Imaging quality is the key performance for the final imaging results. Using a commercial test target (such as the USAF target [19] and the Siemens-star target [13] ), the quantitative spatial resolution can be acquired by analyzing the line pair in the images. However, the analysis of the spatial resolution via this method requires the data statistics to be high enough.…”

“…In our previous studies, the neutron-sensitive image intensifier was used to perform energy-resolved neutron imaging with spatial resolution for about 100 µm per line pair by coupling a time-stamping camera with 55 µm×55 µm pixel size and implementing a centroiding algorithm. [13] The spatial resolution can be improved by decreasing the optical magnification with the decrease in the field-of-view (FOV). Compared with the imaging results of this experiment, better spatial resolution was achieved with the same optical magnification and smaller pixel size, even though no reconstruction process was performed.…”

“…In our previous work, a neutron-sensitive image intensifier was developed by coupling a neutron-sensitive microchannel plate (nMCP), a standard microchannel plate (MCP), and a phosphor screen. [13] In such a device, the process of neutron conversion and light magnification can be realized, which helps to decrease the complexity of the imaging system. It not only meets the demands of specific neutron imaging experiments, such as energy-resolved neutron imaging and high-resolution imaging in low-flux neutron sources, but can also be used in normal neutron imaging experiments.…”

“…[14] With a neutron-sensitive image intensifier, the clusters triggered by neutrons are spatially continuous. [13] This means that analyzing the neutron events in a neutron image intensifier is easier and clearer than that in a standard image intensifier.…”