CAREER: Cosmic Ray Composition across Five Decades in Energy (50 TeV to 5 EeV) with the IceCube Neutrino Observatory

这一奖项的部分资金来自2021年美国救援计划法案(公法117-2)。100多年来，我们一直知道宇宙射线不断地轰炸我们的大气层，影响我们在地球上的日常生活。宇宙射线被认为是在宇宙遥远的地方产生的，在一些最猛烈的观测到的天体物理过程中。然而，关于宇宙射线的产生、加速和在宇宙中传播的过程的关键信息仍然缺乏。然而，已经开发出了候选理论模型，可以对在地球上可观测到的宇宙线参数进行可测试的预测。为了测试这些模型，需要从一个单一的天文台对广泛的能量范围内的宇宙射线的各个元素光谱进行精确和准确的实验测量。这个项目试图在一个重要的能量范围内增进对依赖能量的宇宙线成分的了解，该能量范围将把直接观测方法和间接方法联系起来。直接方法包括以相对较高的精度测量宇宙线粒子的实验。间接方法包括测量宇宙线粒子与南极深处的大气或冰的相互作用的实验。间接方法比直接方法更有可能记录到更多、更高的能量相互作用。这些更高能量的相互作用对于理解宇宙射线的最高能量天体物理来源具有持续的科学兴趣。目前对依赖能量的宇宙线组成的理解具有很大的不确定性，当直接和间接方法能够交叉校准时，这些不确定性将会减少，从而在该领域取得显着进展。该项目还将侧重于与宇宙粒子有关的科学教育，特别是与威斯康星州密尔沃基及其周围历史上代表性不足的群体有关的科学教育。此外，该项目将有助于提高首席研究人员(PI)大学和相关科学合作的跨文化能力(ICC)。该项目将利用南极的三个单独的探测器元件：IceAct(两个最近部署的空气切伦科夫探测器原型)、IceTop(近地表冰内光学传感器)和IceCube(深冰立方千米光学传感器阵列)，目标是测量从~50TeV到~5EEV的50年能量范围内的宇宙射线成分。特别值得注意的是，这项研究将允许相互作用的宇宙射线逐个事件的质量组成，而不是用统计方法处理数据。该提案概述了三个目标，每个目标都导致出版，分成由首席调查员和一名新获得资助的博士后研究员进行的研究的子任务。这项研究涉及新的模拟和开发新的数据分析工具和技术。目标1涉及在初步水平上改进IceAct/IceCube重建、校准和分析，以间接测量能量范围内的宇宙线成分，并使之能够与探测和精确测量宇宙粒子的实验的直接测量进行比较。目标2包括改进PI以前使用IceTop/IceCube在较高能量下的宇宙线组成方面的工作，并提高精度。目标3是使用两种方法确定广泛能量范围内的宇宙线成分：结合目标1和2的结果以及对IceAct/IceTop/IceCube数据和模拟的综合全球分析。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in part under the American Rescue Plan Act of 2021 (Public Law 117-2)For more than 100 years we have known that cosmic rays constantly bombard our atmosphere and affect our daily lives on Earth. Cosmic rays are thought to be produced in the far reaches of the universe in some of the most violent observed astrophysical processes. Yet key information regarding the processes of cosmic ray creation, acceleration, and propagation through the universe is lacking. However, candidate theoretical models have been developed that make testable predictions about cosmic ray parameters that are observable at Earth. To test these models, precise and accurate experimental measurements of the individual elemental spectra of cosmic rays are needed from a single observatory across a wide range in energy. This project seeks to advance knowledge of the energy-dependent cosmic ray composition in an important energy range that will connect direct methods of observation with indirect methods. Direct methods include experiments that measure the cosmic ray particles with a relatively high degree of precision. Indirect methods include experiments that measure the interactions of cosmic ray particles with either the atmosphere or ice deep below the South Pole. Indirect methods are more likely to record many more and much higher energy interactions than direct methods. These higher energy interactions are of continuing scientific interest to understand the highest energy astrophysical sources of the cosmic rays. The current understanding of the energy-dependent cosmic ray composition has large uncertainties that will be reduced when the direct and indirect methods can be cross calibrated resulting in a significant advance in the field. The project will also focus on science education associated with cosmic particles, especially with historically under-represented groups in and around Milwaukee WI. In addition, the project will help improve intercultural competence (ICC) within the Principal Investigator's (PI's) university and within the scientific collaborations involved.The project will utilize three individual detector elements at the South Pole: IceAct (two recently deployed prototype air Cherenkov detectors), IceTop (near surface intra-ice optical sensors), and IceCube (deep ice cubic km array of optical sensors) with a goal to measure the cosmic ray composition over 5 decades of energy from ~50 TeV to ~5 EeV. Of particular technical note, this research will allow for event-by-event mass composition of interacting cosmic rays rather than treating data with a statistical approach. The proposal outlines three objectives, each leading to publication, divided into subtasks of research conducted by the Principal Investigator and a newly supported postdoctoral researcher. The research involves new simulation and the development of new data analytic tools and techniques. Objective 1 involves improving beyond a preliminary level the IceAct / IceCube reconstruction, calibration, and analysis towards an indirect measurement of the cosmic ray composition over the energy range that connects and allows comparisons with direct measurements by experiments that detect and precisely measure the cosmic particles. Objective 2 involves improving the PI's previous work on cosmic ray composition at higher energies using IceTop / IceCube with an increase of precision. Objective 3 is to determine the cosmic ray composition over the broad energy range using two methods: Combining the results of Objectives 1 and 2 and a combined global analysis of IceAct / IceTop / IceCube data and simulation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.