Ultrafast X-Ray Detector and its Gain Uniformity

An ultrafast x-ray detector consisted of an electron pulse time-dilation device, a combined electromagnetic lens system, a microchannel plate (MCP) gated imager, and an electrical pulse generator is reported. The time-dilation device is used to magnify the temporal width of the electron beam created from the photo-cathode (PC), and then the combined electromagnetic lens system images the dilated electron beam onto the MCP. Finally, the MCP imager samples the dilated electron signal and outputs corresponding visible light. A measured temporal resolution of 80 ps for the detector is achieved while the electron pulse is not dilated. The resolution is improved to 12 ps while an excitation pulse with 3.1 V/ps rising edge gradient is used to drive the PC to dilate the electron pulse. Moreover, the gain uniformity of the detector is also tested, which shows the gain is decreased gradually with the excitation pulse propagating on the PC and the drop in gain is about 1.7 ×.