Cosmic Ray Imaging Trigger The Development Of Sub-μ Logic Circuit Card

The cosmic ray muon radiography is a new technique which is appllied to detectfissile nuclear material. When muons pass through the material, the muon trajectory isaffected by coulomb scattering from the atoms in the material. According to imagereconstruction and image algorithm, one can identify fissile material in the materialby the trajectory information so as to realize nondestructive testing of fission nuclearmaterial smuggling for the vehicle, container, etc.In the cosmic ray muon radiography, the trigger logic module is the key part ofthe trigger system, its role is to quickly select valid muon in real-time and generate theprimal trigger signal. The trigger was prepared to minimize accidental trigger ratesand to reject background events that do not originate in the target. A usable eventoccurs when a muon which passes through all six groups of drift tube and thescintillators which provide a trigger signal.To minimize the complexity of the logicthe trigger signal was formed from coincidence of the discriminated signals of bothscintillators S1and S2and a signal from any plane in the topmost drift tube and anyplane in the bottommost drift tube.The paper examines the status quo of the research in cosmic ray muonradiography, investigates the trigger logical circuit that is an important aspect of themuon radiography research, and develops the trigger logical circuit plug-in which canbe used for the cosmic ray muon radiography prototype. Major contributions include:1. Perform theoretical research into working principles of muon radiographyaccording to developments in this area home and abroad, and lay down the structuresand design specifications in line with the research requirements of the circuitcomponent.2. Design the trigger logical circuit component with FPGA properties and LVDSsignal transmission requirements in mind, including power supply design, FPGAdesign, and data interface between the plug-in and the front-end circuits, the interfacebetween the PCB and a computer, and achieve the completion of the plug-in’s PCB design and making.3. Functional modules of the circuit are designed in response to the trigger logicalcircuit‘s functional requirements, using the hardware descriptive language of VerilogHDL. Simulations are carried out on functional modules, and the results show alllogical modules satisfy design requirements.4. Test the proposed plug-in in power supply, serial communication, DAC threshold,functions and delay of the resulting trigger signal. Experimental results demonstratethat the plug-in produces a trigger signal with a width of50ns, and works properly at500kHz. It can achieve programmable delays of S1and S2signals from500ns to810ns with an accuracy of10ns, thereby meeting the demands that the cosmic raymuon radiography prototype imposes for effective muon event selection.The paper develops the trigger logical circuit plug-in of the muon radiographydevices, the module is a6-layer PCB, logical function realized mainly by means of aFPGA chip named EP2C35F484C8N, the module takes LVDS inputs and outputsTTL, by testing each parameter. Tests in parameters of the plug-in justify thefeasibility of the circuit design.