数学形态学在核径迹图像识别中的应用

固体核径迹是一种常用的放射性方法,而粘连核径迹分割是固体核径迹测量分析中的一个难点.本文采用C 语言编程实现的数学形态学算法对固体核径迹图像进行处理,并在实际中应用.结果显示数学形态学算法能有效分割粘连径迹并能够准确有效地计数.     

基于流域算法的重叠核径迹图像分割方法研究

为克服核径迹图像检测过程中径迹交叠造成图像分析的困难,需将实际径迹图像中交叠在一起的径迹群分离为单个径迹.为此,提出了一种基于先验知识的流域分割算法.首先,设定合理的区域面积阈值Ath,标记并剔除图像中的单个径迹区域,结果记为Ms;然后,设定有效腐蚀次数Eth,对粘连区域进行流域分割,结果记为Mc;最后,取Ms与Mc的并集作为分割最终结果.实验结果表明,该算法分割效果好,分割精度高达90%.     

基于数学形态学重叠核径迹图像分离算法的设计与实现

在实际获取的核径迹图像中,经常会遇到重叠现象,即多个核径迹聚集到一起的情形.这给后续的核径迹识别、计数等处理工作带来了较大的困难,因此需要设计一个有效的算法,能够将这些重叠在一起的核径迹分离为单个的径迹.本文针对二值化后的图像提出了一个基于数学形态学的算法.该方法首先利用腐蚀运算,以确定重叠核径迹最终分离为单个径迹的个数,然后再根据腐蚀后的结果,在原始二值图上寻找分离点,从而有效地将重叠核径迹分割开来.本文描述了算法的设计思想,并通过实验给出了结果.     

α粒子径迹法研究硼在各显微组织结构中的分布

微量硼在钢中的作用与其在钢中存在的形式、结构及微观分布有着极其密切的关系。但是,由于硼的原子序数很小,钢中含量又极微(约几十ppm),因此难以观察和测试。α粒子显微径迹照像技术较圆满地解决了这一问题。我们在研究硼在钢中的作用时利用了这一实验技术并结合我们的具体情况进行了改进,特别是在使α粒子径迹像与显微组织的结合方面作了一些工作并取得了一些新的结果,为深入探索硼在钢中的作用机制提供了新的手段。     

重叠核径迹图像的分割与参数统计算法研究

本工作研究重叠核径迹图像分割和参数统计算法。提出了综合运用Otsu全局阈值法和距离变换，并对距离图像进行了二值化处理，有效地将重叠核径迹分割开。在此基础上完成了核径迹的面积、周长、圆形度和质心等参数的统计。计算机模拟结果表明，整个算法简练，运行效率高，且不需人工干预。     

BESIII硅像素探测器寻迹方法的初步研究

随着BESIII漂移室运行时间的增加,其老化问题日趋严重,各种升级替换方案也在研究过程中。论文对替换方案之一的硅像素探测器(SPT)的基本结构、探测原理和初步模拟工作进行了介绍。阐述了硅像素探测器的径迹重建算法的原理、算法的设计和开发。最后使用不同动量的单粒子径迹模拟事例对算法进行调试,并对匹配效率、重建性能和探测器物质量对算法的影响进行了检验和分析。     

JCOGIN粒子追踪算法优化

本文分析了多种先进蒙特卡罗程序的CSG粒子追踪算法，对JCOGIN粒子追踪模块进行了优化。粒子定位算法采取了边界粒子定位和源粒子位置预估，能减少一定量的粒子定位计算；径迹求交算法采取了安全距离优化和布尔二叉树展开，其中安全距离优化可减少电子输运径迹求交次数，布尔二叉树展开能使布尔体求交算法的时间复杂度降为O（n）。应用4个典型算例测试了优化效果，结果表明，粒子定位算法优化对于一般问题具有一定的优化效果，安全距离优化显著提升了电子输运效率，布尔二叉树展开大幅提升了JMCT对于非规则复杂几何的计算速度。     

1.7AGeV84Kr诱发乳胶核反应慢粒子产生

对1.7AGeV⁸⁴Kr诱发乳胶核反应慢粒子产生进行研究。实验结果表明,黑径迹粒子、灰径迹粒子和重电离粒子平均多重数随碰撞中心度及靶核大小的增加而增加;灰径迹粒子和重电离粒子平均多重数随黑径迹粒子数的增加而增加;重电离粒子平均多重数随灰径迹粒子数的增加而增加,而黑径迹粒子平均多重数随灰径迹粒子数的增加表现出先增加后趋于饱和的趋势;灰径迹粒子平均多重数随重电离粒子数的增加而增加,而黑径迹粒子平均多重数随重电离粒子数的增加表现出先增加后趋于饱和。以上结果均可利用核碰撞几何模型来解释。     

基于MATLAB核径迹图像聚焦算法的研究

为了解决噪声对核径迹图像的参数提取、判别、分类与计数以及数据处理的影响,借助MATLAB软件分析了不同焦距核径迹图像的直方图特征、频谱特征和边缘特征,并确定了Robert算子作为对核径迹图像边缘检测的最好算子.同时,以核径迹图像的总灰度值之和取最大值为核径迹图像聚焦质量的评价标准,并按照这个标准设计了显微镜的自动聚焦算法.     

500A MeV 56Fe诱发乳胶核反应慢粒子产生

本文对500A MeV ⁵⁶Fe诱发乳胶核反应慢粒子产生进行研究。实验结果表明,黑径迹粒子、灰径迹粒子和重电离粒子平均多重数随靶核增大而增加;黑径迹粒子平均多重数与入射能量无关,灰径迹粒子平均多重数随入射能量增加而增加;灰径迹粒子和重电离粒子平均多重数随黑径迹粒子数的增加而增加;重电离粒子平均多重数随灰径迹粒子数的增加而增加,而黑径迹粒子平均多重数随灰径迹粒子数的增加先增加后趋于饱和;灰径迹粒子平均多重数随重电离粒子数的增加而增加,而黑径迹粒子平均多重数随重电离粒子数的增加先增加后趋于饱和。     

核乳胶中质子径迹计算机辅助识别方法研究

为克服核乳胶质子径迹人工判读的缺点,研究了一种计算机辅助识别的方法。该方法中,对由显微镜系统获取的核乳胶图像序列依次经组合式滤波器滤波、多阈值二值化、径迹点筛选、径迹点去冗余处理后识别出图像序列中的径迹点,经径迹重建从获取的径迹点中重建出反冲质子径迹。利用该方法从经14.9 MeV中子束辐照的核乳胶中提取出反冲质子径迹,并将提取的径迹与人工判读方法提取的径迹进行了比较,结果基本一致。该方法将为核乳胶质子径迹自动判读系统的开发和核乳胶应用于脉冲中子束能谱测量实验奠定重要技术基础。     

Computer Analysis of Tracks in Nuclear Emulsion Utilizing Digitized Video Scan

A system has developed to make density measurements on particle tracks in nuclear emulsions. The output signal of a videcon viewing the track through a microscope is digitized to detect developed grains in the emulsion. This digitized information is transferred in real time to a computer which selects grains falling in the track and sums their volumes and computes parameters related to their spatial distribution. Analysis of tracks at arbitrary angles is accomplished by rotating the track image in the focal plane with a Pechan prism and by driving the focal plane through the emulsion while taking data.     

电子能损的潜径迹形成机制及理论模型的新进展

潜径迹是荷能离子与固体相互作用的一个重要效应，可以借助化学蚀刻，电子显微镜，卢瑟福散射和其他方法所显同，通过研究依赖于离子能量和各种靶参数的径迹尺寸的变化可以获得关于微观机制的信息，本文概括地介绍了在电子能损体制下径迹形成的基本现象，观测技术以及所获得的重要的实验结果，评价了描述径迹形成机制的理论模型和最新进展。     

Determination of alpha-particle track depths in CR-39 detector from their cross-sections and replica heights

A challenging task in the application of solid-state nuclear track detectors (SSNTDs) is the measurement of depths of the tracks. One approach involves breaking and polishing the side of SSNTDs to reveal the cross-sections of the tracks for direct measurements. Recently, surface profilometry was used to measure the heights of the replicas of alpha-particle tracks to give the track depths. In the present work, systematic comparisons among the track depths for alpha-particles with normal incidence and different incident energies were made for these two methods. After irradiation, the detectors were etched in a 6.25 N aqueous solution of NaOH at 70 °C. Both long etching time of 15 h (to produce spherical-phase tracks) and short etching time from 1 to 8 h (to produce sharp-phase tracks) were used. Good agreement was achieved between the two methods for spherical-phase tracks but not for sharp-phase tracks. It has been found that the surface profilometry method only works for replicas for spherical-phase tracks. Replicas for sharp-phase tracks are easier to collapse or deform, so the surface profilometry method may not give correct results.     

Projected-length distributions of fission-fragment tracks from U and Th thin film sources in muscovite

Thin films of natural uranium and thorium deposited on muscovite were used as sources of neutron-induced fission fragments. Fragment energy loss in thin-source geometry is negligible. In this way, the observed fragment range results from the interaction of the fragment with the detector material. This characteristic enables the investigation of asymmetric fission and etching, through measurements of projected track length distributions in muscovite micas coupled with thin films. The means and standard deviations of the etchable length distributions of the heavy and light fission-fragment tracks were estimated by fitting a theoretical equation to the experimental data.The light fission-fragment accounts for ∼54% and the heavy fission-fragment for ∼46% of the etchable length of a full fission track. This average partition is the same for tracks from thermal-neutron-induced fission of ²³⁵U and fast-neutron-induced fission of ²³²Th. The mean etchable length of uranium fission tracks is ∼2.5% longer than that of thorium fission tracks. This difference is at the resolution limit of these measurements but correlates with the difference in the mean combined initial kinetic energies of the fission fragments. The mean etchable length of uranium fission tracks in muscovite is ∼5% shorter than their calculated latent track length, supporting earlier estimates of a length deficit of this magnitude. The length deficit and the standard deviation of the etchable length distribution of the light fission-fragment tracks are twice the equivalent values for the heavy fission-fragment tracks. This is interpreted in terms of a v_t-profile (track etch rate) that depends on the mass of the track-forming particle.     

PET薄膜中32S离子径迹的热退火效应

采用径迹蚀刻的方法研究了热处理对聚对苯二甲酸乙二醇酯（PET）薄膜中重离子径迹的热退火效应。使用113.7 MeV的³²S离子在PET薄膜中产生垂直于表面且贯穿薄膜的离子径迹。对薄膜进行局部热处理，加热温度为70～240 ℃，时间为1～300 s。薄膜经过化学蚀刻成核孔膜后使用显微镜观测。结果表明：在相同的热处理时间下，随着热处理温度的升高，PET薄膜中离子径迹的热退火效应愈加明显；在热处理温度不变的情况下，随着热处理时间的增加，退火效应亦愈加明显。     

Optical appearance of alpha particle tracks in CR-39 SSNTD

A ray tracing method based on geometrical optics was used to study the tracks from alpha particles with different energies and with an incident angle of 50°. The transmission operation mode of the microscope is simulated. Considering the distribution of light intensities from the tracks, the mean and the 80% percentile gray levels from real experiments are proposed as quantitative variables to differentiate among tracks. The gray level properties for the same track for different exposures can vary to large extents. We introduce three variables, κ, λ and ε, to make empirical corrections. It is interesting to see that these coefficients are very consistent for the same alpha particle track despite the very different gray level properties. Gray level results have been obtained for tracks from alpha particles with 50° incident angle and different incident energies. However, the track depths cannot be predicted by any one of the coefficients κ, λ and ε. Multivariate analyses can help separate the tracks corresponding to different alpha energies. By using discriminant analysis with κ, λ and ε as independents, effectively all alpha energies can be determined with an accuracy of ±0.5 MeV.     

Selective radiography with etched track detectors

A new technique of selective enhancement and evaluation of radiographic images in etched track detectors was developed. It is based on the image processing of individual image element units – etched tracks – by a track analysis system. A selective radiograph is obtained on the basis of the assessment of the size and optical properties of individual tracks. The computer-generated image, in addition to its selectivity, which enables, for instance, multi-elemental analysis from an autoradiograph, also offers a contrast enhancement for better visual observation and/or evaluation. The applicability of the technique is illustrated by selective imaging of ¹⁰B distribution in a whole body samples of a tumour-bearing mouse.