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一个关键的缺失部分。 它们的发现将证明在回答最极端的天体物理来源的性质这个百年问题上是必不可少的。 采用无线电技术的实验是测量UHE中微子最有希望的方法之一，在自然冰环境中发生的这种事件相互作用导致可检测的射频信号在更远的距离上传播。该奖项支持俄亥俄州州立大学的科学家在关键冰参数的研究中进行研究，这些参数直接影响对UHE中微子的首次探测的搜索。 获奖项目将利用跨学科的方法--涵盖中微子天体物理学、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洲阿蒙森-斯科特南极站冰双折射的性质。 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，以评估双折射对下一代用于检测UHE中微子的阵列优化设计的影响。此外，通过ASPIRE计划，高中女生将有机会获得第一手的研究经验。 量化冰中的双折射参数（其中信号的速度取决于其方向和偏振）对于确定中微子相互作用中发射无线电信号的局部偏振是必要的。在冰中产生的信号以两种不同速度的光线传播。 如果双折射参数是已知的，则两条射线之间的时间延迟将是源自冰内的信号的清晰特征，并且提供了事件能量重建所需的相互作用的距离的精确测量。使用在南极部署的阿斯卡里安射电阵列（ARA）进行的脉冲发生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，这些参数可以被纳入一个完整的冰模型，用于检测UHE中微子。将这些信息折叠到预期的无线电发射特征中将降低以前的搜索阈值，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知识价值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.