Yong Wang

The energy distribution of output electrons (EDOE) from a microchannel plate (MCP) is measured using electrons emitted by a vacuum photodiode excited by a 266 nm Ti-sapphire femtosecond laser. The photoelectrons emitted from the photocathode are focused on a specific location of the MCP by a magnetic lens. While exist an enough voltage difference between the two ends of MCP, the energy distribution curve of output electrons form MCP can be obtained by analyzing the data as function of the bias voltage applied to the charge collector. The result shows that the energy distribution curve obtained by this means consists of a sharp and a long tail when using pulse light source. The most probable electron energy (MPE) is 12.64 eV and the full width at half maximum (FWHM) of the energy distribution curve is about 29.23 eV while the applied voltage difference is 700 V in the experimental setup. The MPE is 10.63 eV and the FWHM of the energy distribution is 22.436 eV in simulation. The measured curve is consistent with the expectation from simulation.

A pulse dilation photomultiplier tube (PD-PMT) has been developed. The photoelectrons energy is modulated by a time-dependent electric field between photocathode and ground mesh. Then, the photoelectron pulse is dilated as it transits in a relatively long drift region from mesh to microchannel plate (MCP). The dilated electron pulse is gained by the MCP and then detected by the output collector. Because the temporal width is magnified, the temporal resolution of the photomultiplier tube is better than that of the output collector alone. The result shows that the temporal resolution of the detector is improved to be 25 ps by using pulse-dilation technology, which is much better than 300 ps temporal resolution while without pulse-dilation. The ramp electrical pulse dilates the electron signal to improve the temporal response by about 10 times.