Research Of Readout Method For Energy-resolved Neutron Imaging Instrument At CSNS

The development of manufacturing industry is of great significance to the development of economy.The development history of major powers in the world has strongly proved that the development of manufacturing industry will greatly promote the prosperity of the country and nation.Energy resolved neutron imaging spectrometer is designed according to neutron characteristics,aiming at the requirements of materials,devices,components in the fields of new energy,Emerging materials and precise equipment manufacturing in modern industries,processing and manufacturing,operation and service performance evaluation.The spectrometer will provide scientific data support for solving some bottleneck problems and key scientific and technological problems.Neutrons have the characteristics of fluctuation,uncharged,magnetic moment and strong penetrating ability.They can be used to detect matter by analogy with the well-known X-ray detection principle.Neutrons are a powerful means to study the micro world principle.Neutrons show unique advantages in distinguishing light elements,isotopes and neighboring elements.In addition,the interaction between neutron and sample will not damage the internal structure of the sample,so neutron detection has become an effective means to detect biological samples with activity.The length of neutron wave has advantages for the study of micro structure changes.With the continuous development of neutron source and the continuous improvement of neutron beam intensity,neutron scattering technology has been broadly used in a lot fields,such as microscopic principle of matter,chemical material structure,geological history research,biomedicine and so on.In the past decade,a series of new imaging concepts have made more use of the unique characteristics of neutron radiation to achieve image contrast,which is expected to further expand the potential application of imaging research.Some major technical developments include energy selective(monochromatic)imaging,bragg edge imaging,polarized imaging and resonance absorption imaging.It is worth noting that Bragg edge imaging is an energy selective method,sometimes called energy resolved imaging.Different from other neutron imaging,Bragg edge imaging not only has higher requirements for spatial resolution,but also has higher requirements for temporal resolution due to its energy selective characteristics,which has become the focus of research in recent years.With the improvement of the beam intensity of neutron source,the beam intensity of energy-resolved neutron imaging sample is also increasing.The traditional data readout based on side-by-side structure and two-dimensional cross structure is difficult to meet the demand of high case rate.The application specific integrated circuit data readout scheme based on pixel structure becomes the focus of this paper.According to the characteristics of high temporal resolution and high spatial resolution of energy-resolved neutron imaging spectrometer of China spallation neutron source,the data readout method is studied.Based on the investigation of correlation spectrometer and its readout electronics design,three key problems of high case rate signal conversion,high-speed real-time data processing and high-speed data storage and transmission of neutron imaging detector in energy resolution spectrometer are extracted,and a high-speed distributed real-time data readout method suitable for the characteristics of energy resolution neutron imaging detector is proposed.Timepix3 is used in front-end electronics to read detector signals.The camera with high-density photosensitive unit ensures that the spectrometer system has high spatial resolution.Its high-speed data readout interface and unique event based data readout mechanism guarantee that the spectrometer system has high time resolution.Zynq SoC(System on Chip)series integrates the software programmability of ARM core and the hardware programmability of FPGA,realizes real-time data processing by using the high-speed real-time computing ability of the program logic of SoC,and builds an embedded system based on the processor system of SoC to complete the distributed data upload.The read out electronics introduces white rabbit timing system and neutron pulse identity document system to realize system clock and data synchronization.The function and performance of the electronic prototype circuit are tested,and the performance index of each electronic module meets the design requirements.The high-speed readout method suitable for the characteristics of energy-resolved neutron imaging detector has realized the readout of neutron imaging data with 3×106 n/cm2/s event rate and the best transmission wavelength resolution electronics contribution better than 0.2%.The hardware based real-time multi counting and pixel data processing method realizes the multi counting processing logic,image and energy spectrum real-time statistical logic,which can flexibly configure the multi counting judging conditions,making the processed imaging resolution half.