Time Of Flight Information Extraction In Fission Product Analysis

Time of flight(TOF)measurement is of great significance for nuclear physics experiments.It is widely used in the research of high energy Collider,Large Hadron Collider,Super B plant and future lepton Collider,such as Tevatron,ILC oramuon collider.Which is used to measure the mass of relativistic particles,so it is imperative to study and improve the accuracy of time measurement.In this paper,the flight time measurement system of fission product analysis system is studied,which is divided into three parts: timing discriminator,time digital conversion circuit and timing control circuit.In this paper,based on a large number of time-of-flight measurement literature research in Applied Physics,the composition of time measurement system and the source of time jitter are analyzed.Based on the existing experimental conditions,the research and grading test are carried out.The experiment mainly tests the time performance of timing discrimination and time digital conversion.Based on the principle of constant ratio timing,the timing formula is derived to construct the digital constant ratio timing algorithm.Two groups of discrete data are generated by MATLAB simulation,which meet the requirements of the signal characteristics and signal acquisition parameters of the microchannel board detector.They are used as the test data for timing discrimination.The timing jitter measured in MATLAB is at the ps level,which is suitable for timing discrimination of fast signals.However,due to its signal bandwidth is high,which has certain requirements on the signal acquisition rate.Later,the constant ratio timing circuit is designed and implemented.The timing jitter of the analog constant ratio timing circuit is tested by the signal generator.The measured time jitter is 1.6ns,the timing accuracy is not high,and it is not suitable for high bandwidth fast time signal measurement.The time digital conversion circuit uses the tdc-gpx chip of ACAM company in Germany,and the arm timing control circuit is realized by STM32,the timing control code of arm is written by Keil ?Vision 5,and the TDC chip register is configured to realize the functions of TDC initialization and FIFO reading.The test data is transmitted to the upper computer through ST-Link for data analysis.In order to meet the needs of 8-channel time measurement,I-mode is used to measure and analyze,and the linearity and stability of time measurement are verified.The test results show that the time jitter of single channel is less than 51 ps in the range of 500 ns measurement time,and less than 70 ps in the range of 500 ns to 5 ?s measurement time.