Research On Single Particle Track Imaging Technology And Its Applications In Neutron Spectrum Measurements

The representative parameters of charged particles,including particle types,energy,spatial and temporal distributions,and the interaction with matters,are the main features to be diagnosed in the radiation research area.The detection of neutron and gamma is also achieved by measuring the secondary charged particles produced by their reactions with atoms.Therefore,the measurement accuracy of the charged particles can directly affect,or even determine the results in diagnosis of the neutron radiation field.In order to break through the challenge of accurate diagnosis of neutron energy spectra in low-intensity neutron field fixed with gamma,and at the same time to meet the application requirements of accurate measurement of other weak radiation field,this dissertation studies a novel radiation measurement technique based on the optical imaging of single-particle tracks.Aiming to meet the high diagnostic requirements of radiation measurement system in sensitivity,resolution and other aspects for current applications,a new single-particle track imaging detection system has been developed by studying the technical principle.It mainly consists of a single-particle track scintillating chamber and an optical imaging device,with outstanding performances such as large sensitive area,high spatial resolution,real-time observation and various diagnostic parameters.A series of experimental studies on single-particle track imaging technology have been carried out.Clear track images of single protons,alpha particles and lithium ions were successfully obtained in real time,from which accurate characteristics of experimental Bragg curves,especially the track range and Bragg peak position,were extracted.Based on the track images,high-resolution particle energy spectra were unfolded,and also this new technique was verified with good ability to identify particle types.In addition,track images of low-intensity(<10~5)proton beam have been recorded,and the proton energy resolution of less than 100 keV was also diagnosed by the extracted Bragg peak position distributions.These results establish a solid experimental foundation for the accurate diagnosis of low-intensity neutron energy spectra.To address the difficulty of accurate diagnosis of low-intensity neutron energy spectra,a set of measurement system for neutron energy based on recoil-proton track imaging has been developed.The key performances of the system were analyzed with Monte Carlo simulations to optimize the experimental system.In the DT-fusion neutron measurement,recoil-proton track images were clearly obtained,from which the neutron energy spectrum was unfolded successfully from the track range and the Bragg peak position respectively,demonstrating the feasibility of the novel approach and system for neutron energy.In summary,the single-particle track imaging technology established in this dissertation performs well in many aspects.Compared with the traditional semiconductor detectors,it greatly expands the measurable energy range of charged particles up to hundreds of MeV.Also,its resolution for charged particle energy measurement can be less than 1%,significantly improved compared with the conventional scintillation detectors.Additionally,it can intuitively offer rich information on the features of charged particles,including Bragg Curve distribution,spatial and temporal distributions.Therefore,this is a new detection technology with great value in various important applications,such as medical application research of proton and heavy ion cancer treatment,radiation dose research and fusion research.