Research On Front-end Electronics Of CEE-TPC

Heavy ion collision experiment is one of the main methods to study the properties of low-temperature and high-density nuclear matter.The planned CEE will be the first large-scale nuclear physics experimental device developed independently by China to operate in the Ge V energy region.The development of this device will promote research on scientific issues such as the phase structure of low-temperature and high-density nuclear matter,and the asymmetric equation of the state of nuclear matter at high-density and low temperature.The spectrometer is mainly composed of a superconducting dipole magnet,a start-time detector（T0）,a Time Projection Chambers（TPC）,an internal Time-Of-Flight（i TOF）detectors,a Multi-Wire Drift Chambers（MWDC）,an external Time Of Flight（e TOF）detector,a zero angle calorimeter and other detector systems.Among them,the TPC is one of the most crucial detectors in CEE.It is primarily responsible for measuring the track of charged particles in the large-angle region,and used in conjunction with other detectors to identify the types of particles.A series of requirements for electronics have been put forward by CEE-TPC,such as multi-channel（15,000 channels）,high event rate（10 k Hz）,high integration（single board with 128 channels）,and low power consumption（less than 130m W/channel）.Based on extensive research,at first,this paper proposes a waveform digitization scheme to realize the development of the multi-channel CEE-TPC readout electronics system based on advanced front-end ASIC chip SAMPA and high-performance FPGA.Then through the development of key technologies such as high-density and low-noise circuit design,reliable firmware logic design,and research on high-speed transmission.A single electronics board capable of processing 128-channels of TPC output signals has been completed.Finally,a 512-channel readout electronics system have been accomplished.Upon testing,under laboratory testing conditions,theσ（STandard Deviation）of the baseline noise of every electronics channel is approximately 0.1 f C.The relative amplitude resolution（Full-Width Half Maximum,FWHM）of the output signal is about 23%,with the Minimum Ionizing Particle（MIP）energy loss equivalent input charge（1.4 f C）.In the dynamic range of input charge from 1.4 f C to 100 f C,the readout electronics output amplitude linearity is better than 1%.The time resolution is better than 0.34 ns at an input charge of 40 f C.Results from joint testing with the detector indicate that the baseline noiseσis better than 5 m V.With a ⁵⁵Fe source,an energy resolution（FWHM）of 28.5%was acquired.The cosmic ray track has a position resolution of 388μm in the pad plane and 261μm in the drift direction.In addition,the test results with the magnetic field environment and temperature experiments show that the CEE-TPC readout electronics system can work stability in a 0.5 T magnetic field environment and a temperature range of 0-40℃.Compared to the existing TPC readout electronics based on GET chips,the low-noise,high integration,high-speed asynchronous data reception,and multi-channel parallel processing electronics system developed in this paper increase the counting rate from less than 1 k Hz to 10 k Hz,which effectively solves the readout requirements of large detectors for high integration,high speed and low power consumption of front-end electronics.It lays a solid foundation for the development and mass production of the next large-scale readout electronics system engineering machine for CEE-TPC.