中国散裂中子源反角白光中子束斑测量

The measurement of neutron beam profile will provide fundamental data for subsequent nuclear data measurements and other physical experiments. A high performance intensified CMOS camera based on neutron energy resolved imaging system with time-of-flight technique was developed at China Spallation Neutron Source, and its spatial resolution is less than 1 mm. Some typical characteristic parameters of the neutron beam, such as beam profile, beam size and non-uniformity were obtained and analyzed. At ES1 and ES2 (experiment station 1 and 2), which are about 55 and 75 m away from the target respectively, the FWHMs of neutron beam profile are 55 and 63 mm respectively, and the full widths of 75% maximum are 50 and 60 mm respectively, and the beam profile is well-defined and step like. The results show that the beam profile, size and non-uniformity are not dependent on neutron energy, even the non-uniformity in the center of the beam profile is less than 10%. With the well-defined contour and elegant non-uniformity of the beam profile, the nuclear data can be measured successfully.