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

摘要CRONUS-Earth项目的主要目标是更好地描述各种不确定性，这些不确定性会影响我们利用观测到的宇宙生成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（从而宇宙核素产生率）作为纬度和海拔的函数的模型中的算法，使用了全球中子监测站网络的数据作为参考。因此，确定观测到的中子监测仪计数率和宇宙核素产生率之间的准确响应函数是至关重要的。在这个项目下，特拉华大学小组的主要任务之一是确定中子监测仪对地面宇宙射线空气阵雨粒子的准确探测效率。在两年的努力中，已经确定光子核过程对中子监测仪中伽马射线和e+和e-的计数有很大的贡献。了解中子监测器中这个额外的计数来源可能对比例因子的高度依赖性有重要意义。我们继续研究铅（中子监测器的目标材料）中的光子核巨偶极子共振是至关重要的，这样这个问题就不会延误CRONUS-Earth项目的进展。根据我们迄今为止的研究，宇宙射线中3.3千米（10,000英尺）处的电磁（EM）成分的计数率预计约占总数的4%。值得注意的是，电磁分量通过大气的衰减与强子分量（强子分量是原位宇宙核素产生的主要来源）的衰减有很大不同。我们提出的研究的主要目标是评估这种对中子监测仪计数率的贡献作为海拔高度和地磁截止刚度的函数。我们还将继续研究船舶环境对中子监测纬度测量数据（宇宙核素比例模型的基础）的影响，包括角度效应和电子死区时间。忽略这些影响也会使比例模型产生偏差。我们为期两年的CRONUS-Earth研究的最终结果将有助于改进当前的尺度框架，我们的研究结果将发表一份报告。该提案的更广泛影响是研究生的教育机会。通过实施基于linux的蒙特卡罗模拟粒子和核在大气中的相互作用和中子监测器，该项目将涉及使用计算，数学和物理的基本原理解决问题。

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.