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

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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.