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

克罗诺斯-地球计划的主要目标是更好地描述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各种不确定因素。为了验证用于预测宇宙射线通量(因此，宇宙核素产生率)作为纬度和海拔函数的模型中的算法，使用来自全球中子监测站网络的数据作为参考。因此，确定与观测到的中子监测器计数率和宇宙核素产生率相关的准确响应函数是至关重要的。特拉华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，已经确定光核过程在中子监测器中贡献了大量来自伽马射线以及e+和e-的计数。了解中子监测器中这一额外的计数来源可能会对刻度因子的海拔相关性产生重大影响。继续研究铅(中子监测器的靶材)中的光核巨偶极子共振是至关重要的，这样这个问题才不会阻碍克罗诺斯-地球计划的进展。根据我们迄今的研究，3.3公里(10,000英尺)处宇宙线中电磁(EM)分量的计数率预计约占总数的4%。重要的是，电磁成分在大气中的衰减与强子成分的衰减有很大不同(强子成分是就地产生宇宙核素的主要来源)。我们提议的研究的主要目标是评估这种对中子监测器计数率的贡献作为海拔和地磁截止硬度的函数。我们还将继续调查船舶环境对中子监测纬度测量数据(宇宙成因核素定标模型所基于的数据)的影响，包括角度效应和电子死区时间。忽视这些影响也可能使比例模型产生偏差。这项为期两年的克罗诺斯-地球研究的最终结果将有助于改善目前的规模框架，我们的发现报告将发表。这项提议的更广泛影响是研究生的教育机会。通过实施基于Linux的大气中粒子和核相互作用的蒙特卡罗模拟和中子监测器，该项目将涉及使用计算、数学和物理的基本原理来解决问题。

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.