Design And Test Of Photomultiplier Tube’s Front-ended Readout Circuit

Positron Emission Tomography (PET) is one kind of nuclear medicine imaging technology that obtains organ information. By measuring Electron-positron annihilation radiation caused by Positron radionuclide, it provides organ images with image reconstruction techniques. Produced by Hamamatsu, the position sensitive flat-panel multi-anode photomultiplier tube H9500was selected as the research priorities. When expecting to improve the detector’s spatial resolution, a new severe problem emerged:dramatic increase in output channels. Learning from the H8500’s simplified readout method, many researchers are doing their best with H9500.Based on this background, after designing and testing the discretized positioning circuits (DPC), it was found that an application-specific circuit that contains a charge sensitive pre-amplifier (CSP) and a shaper was needed. The pre-amplifier converts the weak current of H9500to voltage, while the shaper, composed by the CR-RC circuit, shapes and amplifies it. Results show that the CSP is only sensitive to the amount of input charge between22pC and65pC, its output voltage ranges from200mV to3.87V, with a rising time of40ns and falling time of2p.s. The input-output linearity is about0.994, with the Signal to Noise Ratio as high as49.3dB. The CSP works properly to drive the charge distribution DPC so as to improve the resolution.The successfully designed CSP, combined with the charge distribution DPC, will greatly reduce the electronics processing circuit of PET system that based on H9500, and is an important basis for the popularization of high performance PET system.