Research on proton beam spot imaging based on pixelated gamma detector.

The primary secondary particles from the spallation target of the China Spallation Neutron Source are mainly gammas and neutrons, which are related to the distribution of the incident proton. The reconstruction of proton beam spot could be implemented based on the distribution of secondary particles. The methods of pinhole imaging and Compton imaging are developed by measuring the gamma distribution based on the pixelated detector. The secondary gammas could be detected by the pixelated gamma detector directly. The neutron can be identified by detecting the characteristic (478 keV) $\gamma$-rays from the $^{10}B$(n, $\alpha$) reactions. In order to detect secondary neutrons, a layer of $^{10}B$ converter is added before the pixelated gamma detector. The pixelated gamma detector is sensitive to the characteristic (478 keV) $\gamma$-rays and then the neutron imaging could be achieved based on measuring the distribution of the characteristic gamma.