The Research On ATCA-based Data Acquisition System In Direct Dark Matter Detection Experiments

In the particle physics experiments,the implementation of detector signals readout and data acquisition are mostly based on bus systems.In order to realize the processing of complex signals and access to massive amount of data,bus system is indispensable.Various bus systems like CAMAC?FASTBUS?VME and PXI have been widely applied to readout electronics of particle physics experiments.For example,BESIII readout electronics is based on VME bus and HIRFL-CSR(Cooling Storage Ring in the Heavy Ion Research Facility at Lanzhou)readout electronics is based on PXI bus.However,with the expansion of experiment scale and development of detection technology,high bandwidth data transmission will become a big challenge for the design of readout electronics,so that the traditional parallel bus technology can not meet the bandwidth requirement,and utlizing new bus platform and serial bus technology will be a trend in the future experiment development.In this case,we first made an investigation of Advanced Telecom Computing Architecture(ATCA)technology.It is based on point-to-point serial connections and does not require interrupt arbitration like shared bus,so that real-time data transmission and parallel processing between different readout modules can be achieved,which will greatly minimize the system delay and improve work efficiency.At present,the ATCA architecture has been used in some particle physics experiments,such as the high performance computing nodes designed for PANDA experiment and the Fast Tracker system in the trigger processing of ATLAS experiment,and in this dissertation we introduce their specific design and implementation,which provides reference for our design of data acquisition system based on the ATCA platform.In recent years,to further improve the detection sensitivity,many dark matter direct detection experiments have been upgraded by increasing experiment scale and utilizing higher-speed higher-precision waveform digitization method,which bring a lot amount of data as well as put forward higher requirement for the data transmission bandwidth and processing capability of electronics system.Therfore,it is necessary to find a reasonable solution to ensure stable and reliable data acquisition.Under this circumstance,combined with previous research,this dissertation proposes a scalable data acquisition system based on the ATCA architecture.High-bandwidth optical fiber,gigabit Ethernet technology and high-speed serial connections of ATCA backplane are employed to realize mass data transmission.In this dissertation,an ATCA-based prototype data acquisition system aimed for direct dark matter ditection experiments was designed.It is composed of Front-End Cards(FEC)and two kinds of ATCA modules:the Trigger-Clock Module(TCM)to perform trigger generation and clock distribution,and the Data Concentration Module(DCM)to collect data from FECs via 16 10 Gbps optical-fibre serial links.In the DCM,an FPGA device is implemented for real-time data processing.After data processed,valid event data parsed from data stream of FECs is fed into Ethernet switch via a gigabit Ethernet link,and trigger information is transmitted to the TCM through ATCA backplane.The kernel trigger processing is implemented in the FPGA of TCM,and with abundant logic resources in the FPGA,reconfigurable trigger algorithm can be achieved of great flexibility.In the same time,the whole prototype system is operated under a common clock provided by the TCM.An ATCA crate can support up to 208 front-end waveform digitization modules,corresponding to 1664 PMT readout channels.To evaluate the performance of the prototype data acquisition system,a series of tests have been conducted in the laboratory.Firstly we tested the ADC performance of the FEC,and then eye diagram measurement and bit error rate test were conducted to evaluate the data transmission quality,including optical fiber communication between FEC and DCM,ATCA banckplane serial links and gigabit Ethernet data transmission link.Then we also tested the performance of the synchronous clock signal fanned out by TCM.In addition,a small system was set up,and basic trigger function was verified.The test results indicate that the data transmission is stable and reliable and prove the feasibility of the prototype system.Finally,this dissertation summarizes the research on the ATCA-based prototype data acquisition system aiming for the dark matter direct detection experiments,and looks forward to the next step.Based on the future requirements,some improvements are also proposed.