Study On Readout Electronics System For PandaX-? Experiment

Neutrinoless double beta decay(NLDBD)experiment is now regarded as the topmost promising technique to explore the nature of neutrinos after the discovery of neutrino oscillations.NLDBD is a conjectured double beta decay process without emitting neutrinos.The discovery of NLDBD will have great impact to the fundamental of high energy physics for proving that neutrino is a Majorana fermion,breaking the conservation law of the lepton number,measuring the mass of the neutrinos and exploring new mass production mechanism.Scientists estimate that the NLDBD half-life of some isotope is up to 1027 year,requiring the detection experiment has ultra-low background,high energy resolution,and large number of statistical cases.At present,many experiments such as GERDA,CUORE,NEXT and EXO have been carried out,but no detection of NLDBD has been clearly confirmed.PandaX-? experiment will be the first large scale NLDBD experiment in China.Using a high pressure gaseous Xe Time Projection Chamber(TPC)and Microbulk Micromegas detector to read the endplate,and locating at the deepest underground laboratory in the world China Jinping Underground Laboratory(CJPL),this experiment is expected to gain leading position in the competition of NLDBD detection.The main work of this thesis is design of readout electronics system for the PandaX-?experiment,realization of backend electronics,system integration and joint test.Firstly,this thesis summarizes the characteristics of PandaX-? TPC and Micromegas detector and analyzes detailed requirements of readout electronics.This experiment has 10496 anode signal readout channels,82 mesh signal readout channels,10 Hz event rate and some analog performance requirements.Since PandaX-?experiment has large number of readout channels and the possibility of scaling up,this thesis combines related experiment readout electronics and proposes a fiber-link based scalable readout electronics system.This electronics system is divided into two parts:front-end part and back-end part.The front-end part uses ASIC+ADC+FPGA to readout and transmits digitized signals to the back-end part through customized protocol optical links.Front-end electronics include Front-end Card(FEC)for anode signal readout and Mesh Readout Card(MRC)for mesh signal readout.The back end electronics include Data Collection Module(DCM)for data integration and Master Trigger Clock Module(MTCM)for global clock trigger generation and distribution.Design and implementation of readout electronics is explained in detail.FEC uses 4 AGET chips to readout 256 channel anode strip signals,after digitization data are sent to FPGA,and then sent to DCM through optical fiber link.MRC uses discrete components to process 41 mesh signals and generates mesh trigger signal,and then sends it to MTCM through optical fiber link.DCM summarizes,caches and packages the multi-channel data,and transfers them to PC through Gigabit Ethernet link.MTCM receives self-trig and mesh trig signals,generates global trigger signal,and distributes it to FECs via DCM.In order to study the feasibility of readout scheme and to cooperate prototype TPC test,we firstly design a prototype readout system.This readout system is composed of 1 DCM combined with 4 FECs and 1 MRC,and the fiber link is based on FPGA embedded high speed serial transceivers.Electronics test showed that the system functions well,fiber link is stable,system trigger rate can reach 280 Hz,and Ethernet transmission rate is up to 650 Mbps,demonstrating that this prototype readout system meets design requirements.Next,an engineering verification readout system is carried out.In this system,DCM is required to readout 21 FECs.This scheme uses regular IO pin and a customized protocol to transmission optical fiber signal.After testing,the optical link is stable and reliable,and global clock trigger distribution functions well.This electronic satisfies PandaX-? experiment engineering project requirement.Finally,we conducted a series of joint test with detectors.Firstly,this thesis carries out joint test with prototype TPC using the prototype readout electronics system,a preliminary energy spectrum and imaging test results are obtained.In order to verify the concept of scalability and compatibility,this thesis conducted several tests with various MPGD modules,and beam current monitoring in China Spallation Neutron Source.This paper also explores the possibility of SiPIN detector readout combining with a SKIROC2a based front-end card.In summary,this thesis designs a read-out electronics system for PandaX-?experiment.Electronics test and detector joint test proves this system has satisfied design requirements.At the end of the thesis,suggestions on the future work and implementation of the project are discussed.