Proposal for the continuation of a programme of Neutrino Factory research and development

点击翻译按钮获取中文摘要

The species of particles currently known to physics, the neutrinos, which come in three types: electron, muon, and tau, are probably among the most intriguing but least understood. The neutrinos have tiny masses and interact with matter only very weakly. The results of all particle physics experiments to date have been readily explained by the 'Standard Model' of particle physics, developed in the 1960s: that is, except, for a small set of results from a select few experiments investigating the behaviour of neutrinos. Neutrinos are naturally produced continuously in stars and the earth's atmosphere. Experiments to detect these neutrinos have consistently found fewer neutrinos than are produced. So where did they go? There is evidence that these 'missing' neutrinos have changed or 'oscillated' into different types of neutrino, that are not detected. More recently, experiments involving man-made neutrinos have demonstrated similar neutrino oscillation behaviour. For each particle type in nature, there is a corresponding anti-particle type - the anti-particles together are known as anti-matter. So, for each of the three types of neutrinos, there is a corresponding type of anti-neutrino. Of particular interest is the question of whether the oscillations of anti-neutrinos are the same as those of neutrinos, or do the anti-neutrinos behave differently? This question is believed to be related to the fact that the observable universe today is composed almost entirely of matter, whereas the Big Bang which created the Universe 14 billion years ago, should have created equal amounts of matter and anti-matter. The mystery of where the anti-matter has gone could be explained by a difference in the oscillation behaviour of neutrinos and anti-neutrinos. This question can only be answered by making ultra-sensitive measurements of neutrino oscillations using high-intensity man-made beams of neutrinos. The ultimate goal of the proposed research is to produce the most intense beams of neutrinos ever created by man in a 'Neutrino Factory'. These beams of neutrinos will be directed at various angles through the Earth, to different detectors in several parts of the world, allowing the neutrino oscillations to be measured over different distances. This will allow the properties of the neutrinos to be determined far more precisely than ever before, and will allow us to answer the fundamental question of whether the oscillations of neutrinos and anti-neutrinos are the same or not. This should solve the puzzle of where the anti-matter created at the Big Bang has gone, and therefore help to explain the existence of the universe as we know it today.