SGER: Extending Aspects of the CRONUS-Earth Project at the University of Delaware

SGER：特拉华大学 CRONUS-Earth 项目的扩展

• 批准号: 0744568
• 负责人: John Clem
• 金额: --
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0744568&HistoricalAwards=false
• 关键词: SGER; Extending; Aspects; CRONUS; Earth

ABSTRACTThe primary goal of the CRONUS-Earth Project is to better characterize the various uncertainties affecting our ability to utilize observed in situ cosmogenic nuclides as a dating tool. To verify algorithms in models used to predict cosmic-ray fluxes (and hence, cosmogenic nuclide production rates) as a function of latitude and altitude, data from the global network of neutron monitor stations are used as a reference. Therefore, it is critical to determine an accurate response function relating the observed neutron monitor count rates and the cosmogenic nuclide production rate. One of the primary tasks of the University of Delaware group under this project is to determine an accurate detection efficiency of the neutron monitor to ground level cosmic ray air shower particles. During the two-year effort it has been determined that the photonuclear process contributes a significant number of counts in a neutron monitor from gamma rays and e+ and e-. Understanding this additional source of counts in neutron monitors may have significant implications for the altitude dependence of scaling factors. It is critical we continue to investigate the photonuclear Giant Dipole Resonance in lead (the target material in neutron monitor), so that this issue will not delay the progress of the CRONUS-Earth project.Based on our research to date, the count rate from the electromagnetic (EM) component in cosmic rays at 3.3 km (10,000 ft) is expected be roughly ~4 percent of the total. Significantly, the attenuation of the EM component through the atmosphere is considerably different than that of the hadronic component(which is the dominant source of in situ cosmogenic nuclide production). The primary goal of our proposed research is to evaluate this contribution to neutron monitor count rates as a function of altitude and geomagnetic cutoff rigidity. We also will continue investigating the ship environmental effect on the neutron-monitor latitude-survey data (on which cosmogenic nuclide scaling models are based), including angular effects and electronic dead-times. Neglecting these effects could also bias scaling models. The final results from this 2-year continuation of our CRONUS-Earth research will help to improve the current scaling frameworks, and a report of our findings will be published.The Broader Impacts of this proposal is educational opportunities for graduate students. Throughthe implementation a LINUX-based Monte Carlo simulation of particle and nuclear interactionsin the atmosphere and a neutron monitor, this project will involve problem solving using basicprinciples in computing, mathematics and physics.

摘要CRONUS-地球计划的主要目标是更好地描述各种不确定性，这些不确定性影响我们利用观测到的原位宇宙成因核素作为测年工具的能力。为了验证用于预测宇宙射线通量（从而预测宇宙成因核素产生率）随纬度和高度变化的模型中的算法，使用了全球中子监测站网络的数据作为参考。因此，关键是要确定一个准确的响应函数相关的中子监测器计数率和宇宙成因核素生产率。特拉华州大学小组在该项目下的主要任务之一是确定中子监测器对地面宇宙线空气簇射粒子的准确探测效率。在两年的努力中，已经确定，光核过程有助于从伽马射线和e+和e-的中子监测器中的显着数量的计数。了解这一额外的中子监测器的计数源可能有显着的影响高度依赖的比例因子。我们继续研究铅（中子监测器的目标材料）中的光核巨偶极共振是至关重要的，这样这个问题就不会拖延CRONUS-Earth项目的进展。根据我们迄今为止的研究，3.3 km（10，000英尺）处宇宙射线中电磁（EM）分量的计数率预计约为总数的4%。值得注意的是，电磁成分通过大气的衰减与强子成分的衰减有很大的不同（强子成分是原位宇宙成因核素产生的主要来源）。我们提出的研究的主要目标是评估这种贡献的中子监测器计数率作为一个功能的高度和地磁截止刚度。我们还将继续调查船舶环境对中子监测器纬度测量数据（宇宙成因核素定标模型的基础）的影响，包括角度效应和电子死区时间。忽略这些影响也可能使缩放模型产生偏差。我们为期2年的CRONUS-Earth研究的最终结果将有助于改进当前的缩放框架，我们的研究结果报告将被发表。这项提议的更广泛影响是为研究生提供教育机会。除了实施基于Linux的粒子和核在大气中相互作用的蒙特卡罗模拟和中子监测器外，该项目将涉及使用计算，数学和物理学的基本原理解决问题。