A search for sub-dominant neutrino oscillations and measurement of the third neutrino mixing angle, theta13, with the Double Chooz experiment

通过 Double Chooz 实验寻找次主导中微子振荡并测量第三中微子混合角 theta13

• 批准号: PP/E005128/1
• 负责人: Jeffrey Hartnell
• 金额: $ 26.83万
• 依托单位: University of Sussex
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=PP%2FE005128%2F1
• 关键词: search; sub; dominant; neutrino; oscillations

What are neutrinos? Neutrinos are fundamental particles of Nature and despite being one of the most abundant particles in the Universe, the first observation of a neutrino was only 50 years ago. This highly elusive nature of neutrinos comes from the fact that they hardly ever interact with anything around them. Douglas Adams once described the chance of a neutrino interacting as it passes through the Earth as being 'roughly comparable to that of dropping a ball bearing at random from a cruising 747 and hitting, say, an egg sandwich'. Neutrinos weigh at least a 1/4 of a million times less than the electron, which is the next lightest particle and they could be much lighter still. It is widely believed that there are many fascinating facts about neutrinos yet to be discovered. This research proposal is about trying to understand and learn more about the special nature of neutrinos. There are three types of neutrino that have been directly seen but there could be more. In the last decade scientists have made a remarkable discovery: that a neutrino born as one type of neutrino can change in to one or both of the other two types of neutrino. But what's really interesting is that the neutrinos change, and then change back, repeatedly. This changing back and forth has been dubbed neutrino oscillations because it happens regularly like the swinging of the pendulum in a grandfather clock. Furthermore, it turns out that Nature only allows a certain fraction of the neutrinos to undergo these changes at any one time. Whether it's 50% of the neutrinos oscillating back and forth between the three types or just 5%, that is a fundamental parameter of Nature and it is the aim of this research proposal to measure that number. A strong source of neutrinos is a nuclear power station and you can detect the neutrinos from a long way away. The walls of the power station are almost completely transparent to the neutrinos and they pass straight through. You can imagine the neutrinos coming from the power station much like the light coming from inside a glass light bulb: it shines out in all directions. Vast numbers of neutrinos are emitted by the power station: around 1000 billion billion are produced every second. The experiment in this research proposal will be located about 1 km from the power station and it will detect only about one hundred neutrinos out of the billions passing through every 24 hours. If the neutrinos detected in this experiment were found to be changing type then it would be a tremendously important discovery. This is true not only because a fundamental constant of Nature would have been measured for the first time but it would also tell us whether neutrinos might hold the answers to a long outstanding mystery, namely where all the anti-matter in the Universe has gone. The Universe today is filled with matter and very little antimatter. But when it was formed in the Big Bang, equal amounts of matter and antimatter were made. Exactly what happened to all the antimatter is an intriguing puzzle and it is possible that by learning about neutrinos we will find the answer. If this experiment sees neutrinos from the power station oscillating then that will tell us whether it's possible for the behaviour of neutrinos and anti-neutrinos to be different. Thus, through studying neutrinos, we may have the beginnings of an answer to one of the big mysteries of the Universe.

什么是中微子？中微子是自然的基本颗粒，尽管是宇宙中最丰富的颗粒之一，但对中微子的第一个观察到仅50年前。中微子的这种高度难以捉摸的本质源于他们几乎与周围的任何事物相互作用。道格拉斯·亚当斯（Douglas Adams）曾经描述过中微子相互作用的机会，因为它通过地球与“与从巡航的747巡游中随机掉下滚珠轴承大致相当，例如鸡蛋三明治”。中微子的重量至少比电子低100万倍，这是下一个最轻的粒子，它们仍然可以更轻松。人们普遍认为，关于中微子尚未发现的许多有趣的事实。这项研究建议是关于试图了解和进一步了解中微子的特殊性质。有三种类型的中微子可以直接看到，但可能还有更多。在过去的十年中，科学家们做出了一个非凡的发现：一种中微子出生的中微子可以改变为其他两种类型的中微子中的一种或两个中微子。但是真正有趣的是中微子改变，然后反复改变。这种来回的变化被称为中微子振荡，因为它经常发生像祖父时钟中摆动的摇摆一样。此外，事实证明，自然只允许中微子的一定一部分可以在任何时候进行这些变化。无论是在这三种类型之间来回振荡的中微子的50％还是仅5％，这是自然界的基本参数，这是该研究建议的目的衡量该数字。中微子的强大来源是一个核电站，您可以从很长一段路程中检测到中微子。电站的墙壁几乎完全透明了中微子，它们直通。您可以想象，来自发电站的中微子很像来自玻璃灯泡内部的灯光：它朝各个方向发光。电站发出了大量的中微子：每秒生产约100亿亿。该研究建议中的实验将位于距离发电站约1公里的位置，它将仅检测到每24小时通过数十亿美元的中微子。如果发现该实验中检测到的中微子正在改变类型，那么这将是一个非常重要的发现。这不仅是因为自然界的基本常数首次衡量，而且还可以告诉我们，中微子是否可以持有长期杰出的奥秘的答案，即宇宙中所有的反物质都在哪里。当今的宇宙充满了物质，几乎没有反物质。但是，当它在大爆炸中形成时，就制作了相等数量的物质和反物质。正是所有反物质发生的事情都是一个有趣的难题，并且有可能了解中微子，我们会找到答案。如果该实验看到电站的中微子振荡，那么这将告诉我们中微子和抗神经诺氏菌的行为是否有可能与众不同。因此，通过研究中微子，我们可能会开始对宇宙大谜之一的答案。