Experimental Particle Identification Using CR-39 Based Solid Nuclear Track Detector

With the development of nuclear physics and the application of nuclear technology,particle detection and identification play an important role in academic field.However,it is difficult to detect and identify the particles in the experiments usually,due to multi reaction products and interference ions in nuclear reactions.It is interested to detecting the type,energy,angular distribution,reaction cross section of particles accurately in nuclear physics and nuclear technology application.Alpha particles and protons are produced in many types of complex nuclear reactions,and it is difficult to be identified respectively.Varied methods have been applied to identify them.Among these methods,the method based solid state nuclear track detector(SSNTD)has irreplaceable advantage.CR-39 is one of the SSNTD with high performance and have many advantages of high sensitivity,low detectable threshold,insensitive to gamma rays,beta rays and electrons.This study do a research on the identification of the alpha particles and protons from two aspects: simulation and experiment.Track growth model and interaction theory between particles and media are applied to simulate the profile and the appearance of the track produced by alpha particles and protons on CR-39 SSNTD.The optimal chemical etching condition of 3~8MeV alpha particles and 1~9MeV protons are also calculated respectively.Corresponding to the optimal etching conditions,the diameters and depths of the tracks,and the tracks’ gray-level are also simulated to identify the alpha particles and the proton with same energy,alpha particles with different energies and protons with different energies,the alpha particle and the proton with similar ranges.In order to verify the stimulated method,CR-39 SSNTD are used to measure the alpha particle and proton.The tracks of the alpha particle are analyzed and compared with simulated results,the difference between them is from 0.37% to 9.7%.These results prove the feasibility and validity of the simulated method preliminarily.Each chapter of this paper is described as follows:Chapter Ⅰ : Introduction.This chapter introduced the background and significance of this study.The principle,advantages and disadvantages of various particle identification methods were showed in detail.An overview of the status of studies on CR-39 was introduced.Finally,the content and purpose of this research were presented.Chapter Ⅱ:The Latent Track of Radiation Damage and The Mechanism of Track Growth.The mechanism of tract growth and formation was briefly introduced,and the ranges and energy loss rate of alpha particles and protons in CR-39 were analyzed in detail.Chapter Ⅲ:Etching Kinetic Simulation.In this chapter,the kinetic model of track etching in the etching stage was introduced.The profile and the appearance of the track produced by alpha particles and protons on CR-39 SSNTD were simulated.The influence of etching temperature and etching time on the diameters and depths of tracks were also analyzed.The optimal etching conditions were calculated for 3~8MeV alpha particles and 1~9MeV protons.Profile of tracks of alpha particles and protons with different energies were simulated according to the optimal etching condition.Chapter Ⅳ:Experimental Identification of Alpha particles and Protons.Weighing method was used to measure the bulk etch rate.The measured result of the bulk etch rate was 10.41μm/h at 98℃etching with a 6.25mol/L NaOH solution.It was compared with the theoretical calculation of 14.87 μm/h to make sure that it was conformed to the CR-39 used in the experiment.The radiation source of 241 Am was used to irradiate the CR-39,and then the irradiated CR-39 was etched layer by layer under the etching condition of 6.25mol/L NaOH solution at 98℃ with etching time of 30 min,60min,90 min,120min,150 min,170min,respectively.The tracks of alpha particles were analyzed and compared with simulated results,the difference between them is between 0.37% and 9.7%.By using CR-39 SSNTD to measure 3MeV alpha particles and 3MeV protons,the tracks of them were totally different with etching by 6.25mol/L NaOH solution at 98℃ for 45 min,and thus easily to be identified.Chapter Ⅴ:Preliminary Identification of Alpha particles and Protons.According to the corresponding optimal etching conditions,the diameters and depths of the tracks,and the tracks’ gray-level were also simulated.Based on these,a method is proposed to identify alpha particles and protons with same energy,alpha particles with different energies,protons with different energies,and alpha particles and protons with similar ranges.Chapter Ⅵ : Summary and Prospects.The main work of the study was summarized,and the possible improvement is prospected.