Advanced Pixel Sensors Based On Monolithic Active Pixel Sensors For Tracking Detectors

Exploring the elemental composition of matter and the interaction between particles has always been the frontier of high-energy physics research.The tracking detector is a device for measuring and reconstructing charged particle trajectory.In high-energy physics experiments,it is crucial to understand and analyze the physical process studied,reconstruct the particle flight path,and determine its position.As the core component of tracking detectors,the research and design of CMOS pixel sensors are fundamental.The essential features of pixel sensors are position resolution,energy resolution,time resolution,readout speed,power consumption,and material budget.Based on the tracking detector project globally,the research adopted Monolithic Active Pixel Sensor(MAPS)and was carried out with the TowerJazz 180 nm CMOS technology.This dissertation mainly studies the advanced CMOS pixel sensor design for tracking detectors regarding position resolution,energy measurement.and readout speed.Since the discovery of Higgs particles on large hadron colliders(LHC)in 2012,the study of Higgs particle characteristics and beyond standard models has become a hot topic in high energy physics.CEPC is the Higgs particle factory proposed and constructed by the Chinese high-energy physics academia as a tool for studying fundamental particles and cosmic structures.We need to develop a dedicated pixel sensor according to the physical requirements of CEPC.In measuring heavy-ion fragmentation cross-section,it is of great significance to distinguish different ion types.Therefore,in EU project STRONG-2020,the research topic of Tracking and Ions Identifications with Minimal Material budget(TIIMM)is proposed.This research aims to develop a new kind of advanced silicon pixel detector based on MAPS that can be used for particle identification,which needs to have high-precision track detection and energy loss measurement capabilities.The main work of this dissertation is as follows:According to the requirements of the vertex detector pre-research in CEPC,a pixel sensor prototype MIC4 with high position resolution,low power consumption,and high-speed readout is designed to realize the detection of Higgs particles with higher precision.The test platform is designed based on KC705 to study its performance.Furthermore,according to the TIIMM research activity,the TIIMM series pixel sensor prototypes are designed to accurately measure the position and energy loss of charged particles simultaneously and can realize higher performance particle recognition.In the research on this subject,the innovation of this dissertation is mainly reflected in the following aspects:1.A fast-response analog front-end circuit is designed according to the high-frequency collision environment of the vertex detector in CEPC.In the MIC4 sensor,the front-end is optimized to achieve low power consumption and low noise.The peaking time is less than 1μs,the output pulse width time is less than 3μs,and the power consumption of the pixel analog part is less than 18 mW/cm2.Compared with the ALPIDE chip,it has a faster response speed and can work in higher frequency collision experiments.2.In the MIC4 sensor,a new high-speed data-driven readout scheme is proposed for the application background of CEPC with a low hit rate and the requirement of high-speed readout.The scheme combines token ring priority coding(Token)and Address-Encoder and Reset-Decoder(AERD)in ALPIDE,which can effectively reduce the readout time of the pixel array.The scheue is applied under a small pixel size of 25×25μm2 with the layout design optimization.The readout speed of MIC4 can reach 30 MHz/hit,which is higher than ALPIDE,but the pixel area is reduced by about 11%.3.For the TIIMM research topic,a series of TIIMM prototypes with accurate measurement of charged particle position and energy loss are designed.In a small pixel size of 40 × 40 μm2,the time-over-threshold(ToT)technique is adopted to integrate 6-bit registers in the pixel,and the maximum measurable electrons is 700 ke-by optimizing the pixel analog part.This performance meets the requirements of the project to achieve a large dynamic range of energy measurement from the minimum ionization particle(MIP)to heavy ions(500 e-～500 ke-).The research results of this dissertation can also be applied to the future experiments of large scientific devices such as Future Circular Collider(FCC),Compact Linear Collider(CLIC),International Linear Collider(ILC),Electron Ion Collider in China(EicC),Super Tau-Charm Facility(STCF)and X-ray computed tomography(CT),In addition,the combination of high-resolution position and energy loss measurements will facilitate the study of new types of highly granular calorimeters and be of great significance for a large variety of subatomic experiments(including nuclear physics)in the future.