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首页> 外文学位 >Atomic force microscopy methods for the analysis of high-LET tracks in CR-39 plastic nuclear track detector.
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Atomic force microscopy methods for the analysis of high-LET tracks in CR-39 plastic nuclear track detector.

机译：原子力显微镜法分析CR-39塑料核径迹探测器中的高LET径迹。

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摘要

Scope and Method of Study. Proton- and neutron-induced target fragmentation reactions generate short-range (∼1-10 mum), high-linear energy transfer (LET) heavy nuclear recoil (HNR) particles that contribute to total radiation dose deposited in healthy tissue in patients undergoing proton cancer therapy and to astronauts during spaceflight. Conventional detection using CR-39 plastic nuclear track detector (PNTD) that has been chemically etched for analysis by standard visible light microscopy fails because the required bulk etch, B ≈ 40 mum removes short-range tracks. We have developed a method based on Atomic Force Microscopy (AFM) to directly measure HNR particle tracks in CR-39 PNTD. Novel algorithms using least squares ellipse fitting and estimation of fitting in an iterative process were developed to enable the analysis of nuclear tracks in AFM data. In irradiations conducted at the Loma Linda University Medical Center (LLUMC) Proton Therapy Facility and the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), targets of varying composition, including a number of elemental targets of high Z, were exposed in contact with layers of CR-39 PNTD to beams of 60 MeV, 230 MeV, and 1 GeV protons at doses between 2 and 10 Gy. Chemical etching of the CR-39 PNTD was performed under standard conditions (50°C, 6.25 N NaOH) for 2-4 hours (removed layer B = 0.5-1.0 mum).;Findings and Conclusions. The use of a short duration chemical etch yielded densities of secondary tracks of 105-10 6 cm-2 using the analysis methods presented in this work for accelerator-based experiments. LET spectra were obtained with good statistics between 200 and 1500 keV/mum and the results were consistent with nonelastic nuclear cross sections. Absorbed dose measurements were also completed for selected detectors, ∼7 x 10-10 Gy ion -1 was measured for 230 MeV protons. Additionally our data are consistent with an isotropic HNR particle production mechanism. The semi-automated analysis method developed in this work has demonstrated the capability of analyzing detectors exposed to fluences of 108 cm-2 for detectors exposed on spacecraft. This method should prove to be broadly applicable in future studies of HNR particles.
机译：研究范围和方法。质子和中子诱导的靶片段化反应会产生短程（〜1-10 um），高线性能量转移（LET）重核后坐力（HNR）颗粒，这些颗粒有助于质子患者健康组织中沉积的总辐射剂量癌症治疗以及太空飞行中的宇航员。使用CR-39塑料核径迹检测器（PNTD）进行的常规检测已失败，因为需要进行整体蚀刻，因此必须通过标准的可见光显微镜对其进行化学蚀刻以进行分析。 40毫米消除短距离音轨。我们已经开发了一种基于原子力显微镜（AFM）的方法来直接测量CR-39 PNTD中的HNR粒子轨迹。开发了使用最小二乘椭圆拟合和在迭代过程中进行拟合估计的新型算法，以能够分析AFM数据中的核径迹。在洛马琳达大学医学中心（LLUMC）质子治疗设施和布鲁克海文国家实验室（BNL）的NASA空间辐射实验室（NSRL）进行的辐照中，暴露了各种成分的靶标，包括许多高Z元素靶标与CR-39 PNTD层接触的60 MeV，230 MeV和1 GeV质子束的剂量为2至10 Gy。在标准条件下（50°C，6.25 N NaOH）对CR-39 PNTD进行化学刻蚀2-4小时（去除的B层= 0.5-1.0 mum）。使用这项工作中基于加速器的实验中介绍的分析方法，使用短时化学蚀刻可产生105-10 6 cm-2的次级磁道密度。获得的LET光谱具有良好的统计值，介于200和1500 keV / mum之间，其结果与非弹性核截面一致。对于选定的检测器，还完成了吸收剂量的测量，对230 MeV质子测量了约7 x 10-10 Gy离子-1。另外，我们的数据与各向同性HNR颗粒产生机理是一致的。在这项工作中开发的半自动分析方法已经证明了对于暴露在航天器上的探测器分析暴露于108 cm-2能量通量的探测器的能力。该方法应被证明可广泛用于未来的HNR颗粒研究。

著录项

  • 作者

    Johnson, Carl E., Jr.;

  • 作者单位

    Oklahoma State University.;

  • 授予单位 Oklahoma State University.;
  • 学科 Physics Radiation.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 186 p.
  • 总页数 186
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 原子核物理学、高能物理学;
  • 关键词

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