Study on the pulse response of a Vacuum Compton Detector for fast gamma/X-ray characterization

Abstract Vacuum Compton detector (VCD) is a type of pulsed gamma/X-ray radiation detector with a fast response time (< 1 ns) and an upper limit for ultrahigh gamma/X-ray intensity detection. VCDs are widely used to measure the time behaviors of various pulsed X-ray generators. However, recent studies have found that the output signal of the detector is superimposed with strong interference signals under the condition of fast-pulse irradiation (full width at half maximum of nearly 1 ns), which negatively impacts the pulse responses of VCDs. In this study, a pulse response model for VCDs is established, and the pulse response characteristics of the VCDs under gamma/X-ray incidence conditions with different pulse durations are studied. The results show that the interferences with the detector output signal come from two aspects under the condition of half width 0.1 ns pulse radiation. One is mainly from the signal reflection caused by the impedance mismatch of the emitter, and the other is from electromagnetic oscillations that form inside the detector and cause strong interference with the output signals of the detector. In the case of a pulse input condition with a half width of 0.5 ns, the interferences with the detector mainly come from the signal reflection caused by the impedance mismatch of the emitter. When the half width of the pulse is 25 ns, the output signals are almost unaffected. This work provides an efficient and accurate method for researching the pulse response characteristics of VCDs and serves as a reference for the impulse response characterization of other types of charge collection detectors.