Research On Key Technologies Of Multi-anode Microchannel Plate Photomultiplier Tubes

Multi-anode microchannel plate photomultiplier tubes(Multi-anode MCP-PMT)have single photon detection capability,time resolution on the order of picoseconds,position resolution on the order of microns to millimeters and low dark noise,while being able to operate in strong magnetic fields.Therefore,it is often used for Positron Emission Tomography(PET)in nuclear medicine,particle identification in high-energy physics experiments,lidar imaging,deep space exploration and other applications.In the thesis,based on the requirement of photodetector with the magnetic field tolerance,fast response and position-sensitive for the particle discriminator at the end cap of the spectrometer of the Super Tau-charm Facility(STCF),we systematically studied the magnetic field tolerance characteristics of the Multi-anode MCP-PMT through simulation for its extreme operating environment with a strong magnetic field of 1T.and develop the circular MCP-PMT with 2×2 anodes and the square MCP-PMT with4×4 anodes.The main research contents and innovation of the thesis are as follows.Smulation research on the mgnetic field tolerance characteristics of Multi-anode MCP-PMT are carried out.The influencing mechanism of the strong magnetic field on the MCP-PMT gain is analyzed by using professional electromagnetic simulation software.The analysis shows that in the strong magnetic field,the competition between the increase of the number of electron multiplication and the decrease of secondary electron yield in the MCP channel leads to the change of its gain,and in the MCP-PMT,the decrease of the electron beam spot size incident to the MCP makes its gain decay.The influence of the electrical structure parameters of the MCP-PMT on its gain,position resolution and other characteristics is systematically simulated and studied in a strong magnetic field.An MCP-PMT that can work stably in a strong magnetic field environment of 1 T is successfully optimized and designed,with the following main structural parameters:a four-electrodes structure,an inclination angle of 12~°for the MCP channel,an aperture diameter of 108),and an aspect ratio of 40/1.The motion of the electron cloud between the components of the MCP-PMT is deflected with the change of the magnetic field direction,resulting in the attenuation of the output signal amplitude;the focusing effect of the strong magnetic field on the electron cloud can effectively reduce the crosstalk signal between the anodes,thus improving the position resolution.The circular MCP-PMT sample tube with 2×2 anodes was designed and developed with the traditional circular multilayer ceramic shell metalized sealing solution.The actual photocathode effective area ratio of the sample tube is 16%,the anode pixel size is 8.84mm×8.84mm,the single photoelectron peak-to-valley ratio is 4.01,the gain is1.56×10~7,the transit time spread(TTS)is 62ps,the rise time is 343ps,and the crosstalk rate is less than 14%.It was successfully applied to the detection of hard X-rays in the double cone ignition experiment.The one-piece square multi-anode microchannel plate photomultiplier tube sealing solution was proposed,which improved the viability of the tube compared with the multilayer ceramic shells metallized sealing solution,and increased the effective photocathode area ratio from 51.8%to 60.8%compared with the circular sample tube.The square MCP-PMT sample tube with 4×4 anodes was successfully developed,with anode pixel size of 9mm×9mm,single photoelectron peak-to-valley ratio of 3.1,TTS of 38.3ps,rise time of 368ps,and gain of 3.3×10~7.By optimizing the impedance matching of the readout circuit and the equivalent inductance of the anodes,the ringing phenomenon in the output waveform of the sample tube is completely eliminated.