共查询到19条相似文献,搜索用时 515 毫秒
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采用固体径迹法并结合火花自动计数器读径迹数的方式测量弱中子场中的中子引发铀产生的裂变碎片,以此得到中子引发铀产生的裂变率。要获得绝对裂变率,需标定固体径迹火花自动计数器效率。 相似文献
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本文介绍在前冲谱仪中重建带电粒子径迹的一种三维约束方法.用最小二乖法求解x2方程,得出满足x2为最小值时的径迹参数.为了减少计算时间,用二维x线作为计算出发点.用蒙特卡罗数据对本方法进行了检验,并与其它方法所得的结果进行了比较.结果说明这一方法的分辨率和正确性均较好. 相似文献
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快重离子辐照聚合物材料时,由于密集电离激发在其路径上产生几纳米直径的潜径迹,径迹形貌受离子种类、离子能量等多种因素的影响.为了研究电子能损对径迹形成所起的作用,利用1.158GeV 的Fe56离子和 1.755GeV Xe136离子在室温真空环境下辐照叠层聚酰亚胺(PI)薄膜,结合傅里叶转换红外光谱(FTIR)分析技术对辐照引起的化学变化进行了测量.聚酰亚胺官能团的降解及炔基的生成是离子辐照聚合物的主要特征,在注量1×1011到6×1012/cm2范围及较宽的电子能损(dE/dX)e范围 (Fe56 离子:2.2 到 5.2 keV/nm, Xe136 离子:8.6 到 11.3 keV/nm)对官能团的断键率及炔基生成率进行了研究. 红外结果显示在实验涉及的能损范围都有炔基生成,应用径迹饱和模型对实验结果进行拟合,不同能损下的平均损伤径迹半径及炔基生成径迹半径被得到,通过热峰模型对实验结果拟合,给出了离子在聚酰亚胺中产生潜径迹的能损阈值,实验给出的径迹形貌的电子能损效应曲线与热峰模型预言走势基本一致.
关键词:
离子辐照
潜径迹
红外光谱
热峰模型 相似文献
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采用最小绝对值方法对几类物质的冲击波速度D与波后粒子速度u的关系进行了直线拟合,并将其与常用的最小二乘法拟合的结果进行了比较。结果显示:对于实验数据分散性较小的密实材料(金属、离子晶体、氧化物等),两种方法拟合的线性系数一致;而对于实验数据分散性较大的一些疏松材料(包括液体等),两种方法拟合的线性系数有差异。对所有物质,最小绝对值法拟合的平均绝对误差比最小二乘法拟合的要小,因而最小绝对值法较最小二乘法有更高的准确性。同时讨论了导致这两种拟合差异的因素。 相似文献
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蒙特卡罗方法在径迹显微技术中的应用 总被引:1,自引:1,他引:0
径迹显微技术(PTA)是研究硼的晶界偏聚的行之有效的方法.本文运用蒙特卡罗方法建立了径迹固体探测器上蚀坑带宽度与晶界区域硼富集带实际宽度之间的对应关系.模拟计算结果表明,蚀坑带宽度受实际富集带宽度和晶界平面与磨面夹角2个因素影响.蚀坑带宽度随晶界硼富集带宽度的增加与晶界面与探测器平面夹角的减小而增加,利用本文程序计算结果,可根据蚀坑带宽度和晶界平面与磨面夹角更准确的获得实际富集带宽度. 相似文献
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Rajesh Kumar K. P. Eappen A. K. Shukla R. M. Tripathi V. D. Puranik 《Indian Journal of Physics》2009,83(6):839-844
Solid State Nuclear Track Detectors (SSNTD) are commonly used for long term measurements of radon, thoron and progeny concentrations.
In the present study, we compared the optical counting method and the spark counting technique for counting the alpha tracks
on LR 115 track detector films. The paper discusses the various parameters that are innate in the process. More than 300 films
were counted by both optical microscope and spark counter and the results are compared. The overall results show that the
tracks obtained by spark counting are marginally less compared to the optical measurement. A linear fit of the data gives
a slope less that one, which indicates that both the methods are almost in good agreement for counting the tracks when the
track density is low. At higher track densities the spark counter gives an underestimation with respect to actual number of
tracks formed, which could be corrected using a relation obtained between the tracks measured by optical method and spark
counting.
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Lü Qi-Wen 《中国物理C(英文版)》2009,33(8)
The reconstruction algorithm for BESⅢ Muon Counter, MucRecAlg, is developed with the object-oriented language C++ in BESⅢ offline software environment. MucRecAlg consists of the following functions: to find track seeds either from extrapolation of tracks in the main drift chamber or from the fired strips in muon counter, to select fired strips associated to the candidate tracks, to fit the candidate tracks with a linear or quadratic function and to calculate other parameters of the tracks for muon identification. Monte Carlo samples are generated to check the performance of the reconstruction package, such as reconstruction efficiency, muon remaining rate and pion rejection rate, etc. The preliminary results show that the pion rejection rate is around 3%-4% while the muon remaining rate is better than 90% in 0.4-1.6 GeV/c momentum region, which meets the requirement as shown in the design report. 相似文献
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滑雪场的雪道坡度信息不仅是雪场规划和建设所需的必要内容,也是滑雪运动员提高成绩、减少运动损伤的重要数据。传统的手动测量方式费时费力,且雪场的低温环境不利于测量人员长时间作业。为了解决滑雪场的雪道坡度计算问题,提出了一种基于激光雷达点云的雪道坡度自动提取算法。使用投影高程差滤波、聚类分割等算法对雪场点云进行预处理,获取雪道边缘特征数据。提出了一种自适应阈值的拟合算法,用于雪道中线的提取,该算法可根据点云数量信息及坐标信息,自动选择阈值拟合雪道中线,消除了实际应用中部分点云数据稀疏或缺失对中线拟合带来的不利影响。数据处理结果表明,该方法计算所得坡度值与多次手动测量平均值之间的相对误差为2.2%。这一方法对激光雷达在雪场目标上的应用、雪场测绘中雪道坡度计算等具有参考意义。 相似文献
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Nuclear emulsions impregnated with thoriumnitrate solution were exposed to the 15·8 MeV bremsstrahlung of the Tübingen betatron. Fission tracks were identified by ionization and range, and their angular distribution relative to the incomingγ-rays was measured. As the origin of fission was unknown, the distributions obtained extend from 0? to 90? only. All tracks with a dip angle less than 50? were accepted, giving a total of 1726 events. The preponderance of fragment emission under 90? is pronounced even in the distribution of projected angles. After some calculation and correction also the distribution of true, spatial angles could be obtained from the data. Although a three constants formula gave the best fit to the distribution observed, the quadrupole term was found not to be statistically significant. We therefore conclude the angular distribution to be of pure dipole form with an anisotropyα=0·55± 0·12. This is in agreement with previous counter experiments. The anisotropy is interpreted in terms of the A. Bohr model, some of the implications of which are discussed. Extension of the measurements to 180? might be feasible by utilizing the ionization properties of fission tracks near the origin. 相似文献
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V.R. Chechetkin 《Physics letters. A》2013,377(45-48):3312-3316
The main statistical distributions applicable to the analysis of genome architecture and genome tracks are briefly discussed and critically assessed. Although the observed features in distributions of element lengths can be equally well fitted by the different statistical approximations, the interpretation of observed regularities may strongly depend on the chosen scheme. We discuss the possible evolution scenarios and describe the main characteristics obtained with different distributions. The expression for the assessment of levels in hierarchical chromatin folding is derived and the quantitative measure of genome architecture inhomogeneity is suggested. This theory provides the ground for the regular statistical study of genome architecture and genome tracks. 相似文献
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The track association problem is a challenging task in dense target environments due to the existence of furcation tracks, cross tracks and combination tracks. At present, most of the track association algorithms experience a substantial decline in accuracy in processing the above three types of tracks. In response to the defect, a track association algorithm based on the weighted association graph is presented. Information divergence is introduced to construct the weighted association graph. And association quality is acquired based on the weighted idea to reflect the association relationship among tracks. The algorithm solves the association problem with furcation tracks, cross tracks and combination tracks effectively, and improves the performance of association algorithms in dense target environments. The simulation results show the effectiveness and the superiority of the algorithm. 相似文献
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Latent nuclear tracks in polymers can occasionally be doped with fullerene solution. A new technique - ‘Fullerene Tracer Profiling’, FTP - allows us to verify the success of the doping procedure by determining the fullerene depth distribution along the tracks. The basic principle of FTP is described, and first examples are given. Fullerene solution is found to penetrate into ion tracks in polyimide, but not into tracks in polypropylene, or into unirradiated polyimide or polypropylene foils. 相似文献