Tackling the mystery of cosmic rays by searching for cosmogenic neutrinos - transforming the ARIANNA pilot program into a discovery instrument

宇宙射线是宇宙中观测到的能量最高的粒子。单个粒子集中的能量超过10^20 eV（~16焦耳），它们的能量比地球上最大的粒子加速器（如欧洲核子研究中心的大型强子对撞机（LHC））所能达到的能量高出7个数量级。对这些超高能宇宙射线（uhecr）的研究使我们得以了解宇宙中最剧烈的现象，如活动星系核或伽马射线爆发，它们可能是超高能宇宙射线的来源。超高能宇宙射线来源的一个关键是宇宙中微子的测量，这些中微子是由宇宙射线与源周围的物质或与CMB光子的相互作用产生的。中微子在宇宙中畅通无阻，通常以亚度的精度指向宇宙射线源，它们的测量将允许在目前激烈争论的不同天体物理场景之间进行严格的区分。相关的中微子能量范围是10^16.5 - 10^20.5 eV，其中中微子的数量是如此罕见，以至于目前的实验（例如冰立方）太小，无法在合理的时间内获得足够的统计数据。ARIANNA高能中微子探测器对这些高能中微子具有足够的灵敏度。ARIANNA高能中微子探测器通过测量冰中的粒子雨通过阿斯卡扬效应产生的无线电发射，以低成本测量南极洲0.5 Teratons的冰。该项目的目标是将ARIANNA试点项目转变为一种发现仪器，有能力首次揭示河外宇宙射线的来源。我将利用我在射电宇宙射线探测方面的经验，提高中微子事件重构能量和角方向的精度和成熟度，因为射电宇宙射线探测的信号与中微子产生的信号非常相似。此外，我将探索不同的方法来识别中微子的味道，包括使用先进的机器学习技术和冰上的tau-中微子敏感天线阵列的构建。所有方法都将在ARIANNA试点项目的数据上进行测试，该项目已经完成，并测量了27亿吨冰。在未来，这些方法可以应用于全尺寸ARIANNA探测器，以有效地搜索宇宙中微子。

Cosmic rays are the most energetic particles observed in the universe. With energies of more than 10^20 eV (~16 Joules) concentrated in a single particle, their energy is seven orders of magnitude larger than the energy achievable in the largest particle accelerators on Earth such as the large hadron collider (LHC) at CERN. The study of these ultra-high-energy cosmic rays (UHECRs) gives access to the most violent phenomena in the universe such as active galactic nuclei or gamma ray bursts which are probable sources of UHECRs.A key to the sources of ultra-high-energy cosmic rays is the measurement of cosmogenic neutrinos that are created by the interactions of cosmic rays with matter surrounding the source or with CMB photons. Neutrinos traverse the universe unimpeded and typically point back to the cosmic-ray source with sub degree accuracy, and their measurement will allow for a stringent discrimination between different astrophysical scenarios which are currently fiercely debated.The relevant neutrino energy range is 10^16.5 – 10^20.5 eV where the amount of neutrinos is so rare that current experiments (e.g. IceCube) are too small to obtain sufficient statistics in reasonable time. Sufficient sensitivity to these high-energy neutrinos can be obtained with the proposed ARIANNA high energy neutrino detector which instruments 0.5 Teratons of ice in Antarctica at low costs by measuring the radio emission created by a particle shower in ice via the Askaryan effect.The goal of this project is to transform the ARIANNA pilot program into a discovery instrument with the capability to reveal the sources of extragalactic cosmic rays for the first time. I will bring my experience with radio-based cosmic ray detection, whose signals are remarkably similar to those generated by neutrinos, to improve the precision and maturity of the reconstructed energy and angular direction of neutrino events. In addition, I will explore different methods to identify the neutrino flavor including the usage of advanced machine learning techniques and the construction of a tau-neutrino sensitive antenna array above the ice. All methods will be tested on data from the ARIANNA pilot program, which is already completed and instruments 2.7 Gigatons of ice. In the future, these methods can be applied to the full-size ARIANNA detector to efficiently search for cosmogenic neutrinos.