Beijing Spectrometer (of Besiii) Time Of Flight Readout Electronics System Design And Implementation,

The Beijing Electron Positron Collider (BEPC) was built in 1989 and its research field covers Tau physics, Charm physics and the precise research of standard model. BPEC consists of the injector, the storage ring, the transportation line, the Beijing Spectrometer (BES), the Beijing Synchrotron Radiation Facility (BSRF), etc.There has been an upgrade in 1996 for BEPC, and the BEPC/BES are called BEPC/BESII afterward. To improving the performance and solving the problem of aging, BEPC will be upgraded again, and the new version of BEPC/BES will be named BEPCII/BESIII.BESIII consists of Main Drift Chamber (MDC), Electromagnetic Calorimeter (EMC), Time-Of-Flight counter (TOF) andμIdentifier, trigger system, etc. The purpose of TOF is to measure the flight time of charged particles. Particle identification is made by comparing the measured time against predicted time obtained from the charged particle track length and momentum given by the Main Drift Chamber. The TOF also provide a fast trigger signal for charged particles, as well as cosmic ray background rejection. The TOF of BESIII contains the barrel part and endcap part. The RMS time resolution of barrel part will be less than 90ps and the endcap part will be less than 110ps. To meet the requirement of BESIII TOF, the Readout System of TOF, consists of the front end electronic (FEE) and Readout Electronic, will contribute less than 25ps RMS uncertainty. This thesis mainly discusses the detail of the implement of BESIII TOF Readout electronic system.Normally, time measure is including time discrimination and time to digital converter (TDC). In the chapter 2, we discuss the characteristic of leading end discriminator, zero crossing discriminator and constant faction discriminator (CDF) and ARC discriminator. Leading end discriminator and CDF discriminator are widely used in high energy experiment. The advantage of leading end discriminator is its simple structure, easy to realized and integrated. But it has timing error because of'time walk' effect. So the result of leading end discriminator needs to be corrected by charge measurement or amplitude measurement, etc. CDF discriminator can eliminate 'time walk' effect, but it is more complicated.In chapter3, some types of TDC are introduced, such as using counter method, TAC+ADC method, and delay chain method. Counter type is the most common technique for time measurement. It is full digital and very simply. But the time resolution of counter type TDC is not very good (about 1ns) because of the frequency of counter. More precise counter type TDC can be implemented by delay chain interpolation technique. Using this technique, CERN has developed a high resolution TDC, named HPTDC.In chapter 4 to chapter 6, the design and test of BESIII TOF Readout Electronic System are discussed. In chapter 4, we introduce some particle collider's TOF electronic, such as BELLE TOF in KEK, ALICE TOF in LHC, CDF TOF in Femi lab, STAR TOF in BNL. Based on the study of these electronics design's principle and the characteristic of BESIII TOF detector, the BESIII TOF Readout Electronic System develops a practical scheme: using leading end discriminator and HPTDC to measurement flight time, and using QTC circuit and HPTDC to measure the charge of the hit signal.In chapter 5, the detail of TOF Readout Electronic System is introduced. It includes Pre_Amplifier and other electronic modules in VME crate. They consist of 14 FEE (Front End Electronic) modules, 1 FEE clock fanout module and 1 FEE fast control module. The function of FEE module is measure the flight time and charge of the coming hit signal. The clock fanout module is responsible for the 41.65Mhz system clock of all modules. And FEE fast control module will receive the control signal (such as L1 trigger) from global trigger system and send the status signal of FEE readout module as well.In chapter 6, we will introduce the test result of TOF electronic, such as time and charge measurement performance. The process of test is including electronic test using signal generator, cosmic test using telescope system and beam test using the LINAC of BEPC in IHEP. All the test result shows that the performance of TOF Readout Electronic System can meet the requirement of BESIII TOF.