Precision Ultra-High Energy Neutrino Astrophysics and New Signatures Enabled by a Complete Treatment of Birefringence in Antarctic Ice

能量大于10^17电子伏特的超高能中微子是快速发展的多信使天体物理学领域中的一个关键缺失部分。它们的发现将被证明是回答最极端天体物理源的性质这一百年问题的关键。使用无线电技术的实验是测量UHE中微子最有希望的实验之一，在自然冰环境中发生的这种事件相互作用导致可检测到的射频信号在千米尺度上传播。该奖项支持俄亥俄州立大学的科学家研究直接影响UHE中微子首次探测的关键冰参数。获奖计划将利用跨学科的方法--横跨中微子天体物理、气候科学、冰川学、遥感、进化计算和天线工程--来解决美国国家科学基金会南极阿蒙森-斯科特南极站的冰双折射特性。本科生研究人员将在跨学科团队中发挥关键作用，包括领导GENETIS项目，以评估双折射对探测UHE中微子的下一代阵列优化设计的影响。此外，通过ASPIRE计划，高中女性将有机会获得第一手研究经验。量化冰层中的双折射参数(其中信号的速度取决于其方向和极化)对于确定在中微子相互作用中发射无线电信号的局部极化是必要的。在冰中产生的信号以两条射线的形式传播，它们以不同的速度传播。如果双折射参数已知，两条射线之间的时间延迟将是源自冰内的信号的明显特征，并提供到事件能量重建所需的相互作用的精确距离的测量。利用部署在南极的阿斯基恩无线电阵列(ARA)进行的脉冲器测量将提供表征冰双折射的最佳拟合深度相关参数。然后，这些参数可以被合并到用于探测UHE中微子的完整冰模型中。将这些信息合并到预期的无线电发射签名中将降低先前的搜索阈值，并加强正在进行的首次探测UHE中微子的搜索。该奖项反映了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。

Ultra-high energy (UHE) neutrinos with energies greater than 10^17 electronvolts are a key missing piece in the rapidly developing field of multi-messenger astrophysics. Their detection will prove essential in answering the century-old question of the nature of the most extreme astrophysical sources. Experiments employing radio techniques are amongst the most promising for measuring UHE neutrinos, where such event interactions occurring in natural ice environments result in detectable radio-frequency signals propagating over kilometer-scale distances. This award supports scientists at the Ohio State University performing research in the study of key ice parameters that directly impact the searches for the first detections of UHE neutrinos. The awarded program will leverage an interdisciplinary approach – spanning neutrino astrophysics, climate science, glaciology, remote sensing, evolutionary computation, and antenna engineering - to address the property of ice birefringence at the NSF’s Amundsen-Scott South Pole Station, Antarctica. Undergraduate researchers will play key roles in the interdisciplinary team, including leading the GENETIS project to assess the impact of birefringence on optimal designs of next-generation arrays for detecting UHE neutrinos. In addition, through the ASPIRE program, high school women will have the opportunity to gain first-hand research experiences. Quantifying the birefringence parameters (where the speed of a signal depends on its direction and polarization) in the ice is necessary to determine the local polarization where a radio signal is emitted in a neutrino interaction. A signal produced in the ice propagates as two rays that travel at different speeds. If the birefringence parameters are known, the time delay between the two rays would be a clear signature of a signal originating from within the ice, and provides a precise measure of the distance to the interaction necessary for the event energy reconstruction. Using pulser measurements taken with the deployed Askaryan Radio Array (ARA) at South Pole will provide the best fit depth-dependent parameters characterizing the ice birefringence. These parameters may then be incorporated into a complete ice model for detection of UHE neutrinos. Folding this information into the expected radio emission signatures will lower previous search thresholds and enhance the on-going search for the first detection of UHE neutrinos.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.