The performance of a planar CdZnTe thermal neutron detector

The nuclide ¹¹³Cd is sensitive to thermal neutrons. Most of the gamma rays generated from ¹¹³Cd${(n,\gamma )}^{114}\mathrm{Cd}$ reactions have an energy of 558 keV. CdZnTe detectors contain Cd-113. Their good energy resolution for gamma rays ensures that they can identify the thermal neutrons by detecting the prompt gamma rays. Planar CdZnTe detectors are easy to manufacture and therefore cheap. Nonetheless, they have not yet been utilized in thermal neutron detection since their spectra lack the 558 keV photopeak, which is essential for identifying neutron capture events. In this paper, a 22 mm$\times$22 mm$\times$0.5 mm planar CdZnTe detector was used to detect the thermal neutrons from the No. 20 neutron beam line of China Spallation Neutron Source. A special detection method was applied to distinguish thermal neutrons from background radiation so that the planar detector was able to detect thermal neutrons. The intrinsic total detection efficiency of the detector for thermal neutrons was measured as 6.58%$\pm$0.76%. The result demonstrates that planar CdZnTe detectors are also able to serve as thermal neutron detectors.