Search for Tau Neutrinos in IceCube Data

冰立方中微子天文台（ICNO）深埋在南极冰盖中，是世界上最大、最灵敏的高能中微子望远镜。它是一个10亿吨的探测器，利用南极冰作为探测高能大气和天体物理中微子的介质。冰立方观测到的大多数中微子的能量都在预期的大气中微子的能量范围内，这些中微子是由来自银河系附近部分的宇宙射线在广泛的空气阵雨中产生的粒子衰变产生的。这些可以用来测量中微子的基本性质。在更高的能量下，天体物理中微子是高能宇宙的关键探测器。由于其独特的性质，中微子甚至可以逃离密集的区域，不受星系或星系外磁场的偏转，并且可以不受阻碍地穿越充满光子的宇宙。因此，中微子提供了关于强大的宇宙物体的动力学和内部的直接信息，这些物体可能是高能宇宙射线的起源：超新星、黑洞、脉冲星、活动星系核和其他极端的河外现象。该奖项为阿拉巴马大学（UA）小组在冰立方数据中寻找一种特殊类型（“风味”）的中微子，即tau中微子提供资金。Tau中微子来自大气的背景可以忽略不计，它将是天体物理学起源的一个特定标志，同时也为中微子物理学和遥远源的振荡提供了见解。PI将继续通过举办冰立方大师班来加强高中的外展：这是一个为期一天的活动，让高中生有机会使用真实的冰立方数据。PI将基于UA小组的tau中微子研究开发一个新的大师班活动。PI参与了突出冰立方独特位置和科学目标的公共宣传活动。如果天体物理学中的中微子通量是由于宇宙射线在激波中加速而产生的介子衰变，并且假设标准的中微子振荡参数，那么在地球上探测到的中微子应该由等量的电子、μ子和τ中微子组成。然而，在天体物理学的中微子流中，tau中微子还没有被明确地识别出来。该小组将以tau中微子通道的可靠记录为基础，将搜索扩展到更低能量和以前未探索的特征。随着冰立方数据的三年多，能量阈值的降低和信号灵敏度的提高，到资助期结束时可以探测到tau中微子。

Embedded deep in the ice cap at the South Pole, the IceCube Neutrino Observatory (ICNO) is the world's largest and most sensitive high energy neutrino telescope. It is a 1 billion-ton detector using the Antarctic ice as a detection medium for high energy atmospheric and astrophysical neutrinos. Most of the neutrinos observed by IceCube exhibit energies in the range expected for atmospheric neutrinos originating from decays of particles produced in extensive air showers by cosmic rays coming from nearby sectors of the Milky Way Galaxy. These may be used to measure the fundamental properties of neutrinos. At higher energies, astrophysical neutrinos are key probes of the high-energy universe. Because of their unique properties, neutrinos escape even dense regions, are not deflected by galactic or extra-galactic magnetic fields and traverse the photon-filled universe unhindered. Thus, neutrinos provide direct information about the dynamics and interiors of the powerful cosmic objects that may be the origins of high energy cosmic rays: supernovae, black holes, pulsars, active galactic nuclei and other extreme extragalactic phenomena. This award provides funding for the University of Alabama (UA) group to search for a particular type ("flavor") of neutrino, the tau neutrino, in the IceCube data. Tau neutrinos have a negligible background from the atmosphere and would be a certain sign of astrophysical origin as well as offering insight into neutrino physics and oscillation in distant sources.The PI will continue and enhance high school outreach by hosting an IceCube Masterclass: a one day event which gives high school students the chance to work with real IceCube data. The PI will develop a new Masterclass activity based on the UA group's tau neutrino research. The PI participates in public outreach activities that highlight IceCube's unique location and science goals.If the astrophysical neutrino flux arises from pion decay as a result of cosmic ray acceleration in shocks, and assuming standard neutrino oscillation parameters, the detected neutrinos at Earth should consist of equal fractions of electron, muon and tau neutrinos. However, tau neutrinos have yet to be unambiguously identified in the astrophysical neutrino flux. The group will build on a proven track record in the tau neutrino channel and extend the search to lower energies and to previously unexplored signatures. With three more years of IceCube data, lower energy thresholds and increased signal sensitivity, tau neutrinos could be detectable by the end of the funding period.