Detection of ultra high energy cosmic ray neutrinos with ANITA and investigation of future large-scale detectors

中微子是宇宙中第二丰富的基本粒子。它们是由太阳产生的，是为太阳提供动力的核反应的副产品，也是地球上放射性衰变的副产品。它们也是在高层大气中由宇宙线相互作用产生的不稳定粒子的衰变产生的。因此，中微子可以告诉我们一些关于宇宙射线的信息，而我们通常对宇宙射线并不完全了解。宇宙射线是恒星爆炸产生的粒子之一，很可能主要是质子，但也可能是更重的原子核-我们还不知道，了解它们的组成和能量可以让我们洞察不同恒星和星系类型的性质。探测中微子告诉我们宇宙的本质，探测能量最高的中微子告诉我们宇宙中最猛烈(通常也是最罕见)的事件。中微子不带电荷，几乎是质量，所以与周围环境的相互作用非常弱--事实上，如果地球和太阳之间的空间充满了铅，来自太阳的中微子仍然会到达地球--你需要100万倍的铅来阻止中微子！因此，中微子可以从宇宙的最边缘旅行，因此从最早的时候开始，仍然可以到达地球。其他粒子无法做到这一点，因为它们往往会被恒星或行星的磁场弯曲，或者被弥漫宇宙的电磁辐射吸收。这种电磁辐射是大爆炸的残余物，造成了模拟电视画面上1%的干扰，其精确测量刚刚获得2006年诺贝尔物理学奖。中微子可以提供其他粒子无法提供的信息。高能中微子往往比低能中微子更容易被吸收，因此我们不应该看到来自非常遥远来源的极高能中微子。如果我们看到非常高能的中微子(在所谓的GZK截止上方)，那么它们是由一种涉及新物理的机制在本地(靠近我们所在的星系)产生的--要么是一种快速加速粒子的新的奇异方式，要么是来自尚未被检测到的新基本粒子的衰变。试图描述宇宙的大尺度性质和原子内部量子工作的理论被称为大统一理论，它们往往预测新的重的、不稳定的粒子的存在。这些不稳定的粒子在衰变时会产生中微子，因此对超高能中微子的观测可能会从大统一理论或新的天文物理加速机制发出新的物理信号。这项提议首次试图利用这些超高能中微子穿越南极冰层时产生的无线电信号(不完全是无线电1号)来测量它们。我们希望使用NASA配备的Wirth无线电气球天线探测到这个信号，该天线将在2006年底在南极洲上空盘旋一个月，然后在2008年底再次悬停。我们还在寻求设计一种新的大规模探测器，它将位于南极洲的罗斯冰架上，它将是一个永久性的中微子探测器，有望揭示新粒子的存在或来自遥远宇宙的某种奇异秘密。

Neutrinos are the second most abundant fundamental particle in the universe. They are produced by the sun as a by-product of the nuclear reactions powering the sun and on earth from radioactive decays. They are also produced in the upper atmosphere from the decays of the unstable particles that are produced by cosmic ray interactions. Neutrinos can thus tell us something about cosmic rays which in general we do not have a very complete understanding of. Cosmic rays are the particles produced amongst other things by exploding stars and are probably mostly protons but may also be heavier nuclei - we don't know yet and understanding their composition and energy can give us an insight into the nature of different star and galaxy types. Detecting neutrinos tells us about the nature of the universe and detecting the most energetic neutrinos tells us something about the most violent (and generally rarest) events in the universe. Neutrinos carry no charge, are almost massles and so only interact very weakly with their surroundings - indeed if the space between the earth and the sun was filled with lead, the neutrinos from the sun would still get to the earth - you would need a million times that distance of lead to stop the neutrinos ! Neutrinos can therefore travel from the very edges of the universe and thus from the earliest times and still reach the earth. Other particles cannot do this since they tend to get bent away by the magnetic fields of stars or planets or absorbed by the electromagnetic radiation that pervades the universe. This electromagnetic radiation is a remnant of the big bang and responsible for 1% of the interference you get on your analog TV picture and its precise measurement was just awarded the 2006 Nobel Prize in physics. Neutrinos can provide information that other particles cannot. Higher energy neutrinos tend to get absorbed easier than lower energy neutrinos and so we should not see extremely high energy neutrinos from very distant sources. If we see very high energy neutrinos (above the so-called GZK cut-off) then they are being produced locally (close to our own galaxy) by a mechanism that involves new physics - either a new exotic way of accelerating a particle quickly or from the decay of a new fundamental particle that is yet to be detected. The theories that seek to describe the large scale nature of the universe and the quantum workings inside the atom are termed grand unified theories and they tend to predict the existence of new heavy, unstable particles. These unstable particles can produce neutrinos when they decay, so the observation of ultra high energy neutrinos may signal new physics from a grand unified theory or a new astro-physical acceleration mechanism. This proposal is seeking to measure these ultra high energy neutrinos for the first time using the radio signal (not quite radio-1) produced as they traverse through the ice of Antartica. We are hoping to detect this signal using a NASA balloon equipped wirth radio antenna that will hover above the Antartica for a month at the end of 2006 and then again at the end of 2008. We are also seeking to design a new large scale detctor that will sit on Antartica's Ross Ice Shelf that willl be a permanent neutrino detector that will hopefully reveal the existence of new particles or some exotic secret from the distant universe.