Study On Readout Electronics System For PandaX-nT Dark Matter Direct Experiment

Modern astronomy has confirmed the existence of dark matter through galaxy rotation curves,gravitational lensing,and cosmic microwave background.And the total mass-energy of the universe contains 4.9%ordinary matter,26.8%dark matter and 68.3%dark energy.The study of dark matter is an important subject of modern cosmology and particle physics.There are three main methods for exploring dark matter:"creating" dark matter particles based on colliders,indirect detection and direct detection.Direct detection of dark matter is mainly to detect the signal generated by the interaction between dark matter particles and the matter in the detector,thereby directly detecting the properties of dark matter particles.At present,many dark matter direct detection experiments have been carried out internationally,such as XENON experiment,LUX experiment,XMASS experiment,etc.These experiments are also being upgraded to increase the sensitivity of dark matter detection.China is also actively carrying out dark matter direct detection experiments.The PandaX experiment,led by Shanghai Jiaotong University and jointly cooperated by many domestic universities and research institutes,is one of them.At this stage,PandaX-? and PandaX-? have completed their missions,and the upgrade of PandaX-nT is under intense development.To further increase the sensitivity of dark matter detection and obtain a higher-precision WIMP particle reaction exclusion cross-section,the upgrade of PandaX-nT is moving towards the tons of target materials,low background and different background discrimination algorithm.The increase in the number of channels,the need for high-speed and high-precision waveform sampling,and the resulting data transmission issues have placed further demands on readout electronics system.The main work of this thesis is to propose and design a prototype readout electronics system for the upgrade of PandaX-nT.The entire prototype readout electronics system includes a pre-amplifier module,a waveform digitization module,and a clock and trigger module.The pre-amplifier module can realize 10 times gain amplification and DC offset adjustment of the PMT output signal in PandaX-nT.The waveform digitization module mainly integrates 8-channel 1GS/s sampling rate and 14bit resolution ADCs.At the same time,the waveform digitization module uses Gigabit Ethernet to exchange data with the data server.Gigabit Ethernet uses TCP-based reliable protocol for transmission,and the transmission rate reaches 600Mbps.And the waveform digitization module also implements 10 Gigabit Ethernet based on UDP protocol,which is reserved for subsequent upgrades.The clock and trigger module is mainly used to provide a synchronized clock and trigger signal to the waveform digitizing module.The data is exchanged between the clock trigger and module and the waveform digitizing module through optical fibers.This thesis also tested the performance of key parts of the entire prototype electronics system,including testing the bandwidth and gain of the preamplifier module;testing the performance of the waveform digitizing module,such as DNL,INL,ENOB,etc.;testing the data transmission part,including Ethernet and optical fiber;Finally,testing the synchronization performance between different channels of the waveform digital module.The test results show that design and performance of the prototype electronics are as expected.Finally,the prototype electronics system was also jointly tested with the PandaX-? detector,which mainly carried out LED calibration PMT gain test and radon radioactive source test.Tests of radon radioactive sources have shown that the prototype electronics system can well distinguish between nuclear recoil and electronic recoil events.The results of the joint test have verified the basic functions of the prototype electronics system.