Study on low noise cryogenic charge readout electronics for liquid xenon time projection chamber

Background Liquid xenon time projection chamber(LXe TPC)is widely used in high-energy physics experiments such as particle detection and neutrino(or neutrinoless)double beta decay.The charge readout accuracy of the LXeTPCdirectly affects the measurement results and success of the experiments.Because liquid xenon needs to maintain a cryogenic temperature between 162 and 165 K at atmospheric pressure,the charge generated in the LXe TPC always needs to be read out in the cryogenic environment for minimizing the input capacitance,which has effect in determining the output noise of the charge amplifier.Purpose Design a charge readout electronics system applicable to LXe TPC and research a data analysis method to get the exact amount of charge by analyzing the waveform at that output of the designed electronics system.Methods Design a multi-channel charge-reading application specific integrated circuit(ASIC)that can operate in the cryogenic environment.The signals and power supply of the ASIC are connected to an electronics system at room temperature through micro-coaxial cables.The electronics at room temperature complete the sampling of the ASIC output.A data acquisition device receives the sampled waveform data and calculates the charge measurement resolution by Gaussian fitting.Results The designed ASIC and selected micro-coaxial cable can work in stable condition under the cryogenic environment of 165 K.The analyzed integral nonlinearity of the charge measurement of the chip is 0.83%in the range from 1 to 50 fC,and the charge measurement resolution of the chip is lower than 900 e−RMS.Conclusion In this paper,a preliminary study of the charge readout method based on the system structure of self-developed ASIC,micro-coaxial cable,and data readout electronics is completed for LXe TPC.The system test results indicate that the designed ASIC can work normally in the cryogenic temperature of 165 K with a high dynamic range and good linearity of the charge measurement.Further work can be done to reduce the charge measurement resolution of the system to 200 e−RMS.