RA post request re Dave Wark's T2k spokesperson position

在过去的十年里，世界各地的实验已经证明，被称为中微子的粒子具有与粒子物理学标准模型中预期的非常不同的性质。在标准模型中，中微子有三种不同的类型，称为"味道"--电子中微子、μ子中微子和τ中微子--这些味道是不可变的。一旦中微子作为一种味道产生，它就永远不会改变。标准模型中微子也被认为没有静止质量，因此总是以光速运动。我们现在知道，中微子实际上是有质量的，而且中微子的味道可以以一种我们称之为"中微子振荡"的特殊方式混合，即一种味道的中微子束在传播过程中会变成另一种味道。T2K实验将对这些中微子振荡进行前所未有的精确测量，希望能更好地理解这一现象，并试图理解中微子振荡对其他物理领域的影响。特别是，中微子振荡是由三个混合角来描述的，这三个混合角会影响不同的味道如何相互混合，而现有的实验只测量了其中的两个角。T2K的目标是观察第三个角度产生的效应，T2K应该比现有的实验灵敏十倍，现有的实验只对这个角度的大小设定了上限。这第三个角度对物理学家来说特别有趣，因为如果它不为零，它就有可能在中微子振荡中观察到称为CP的对称性的破坏。CP破坏将使中微子的振荡不同于反中微子的振荡，这种效应可能与基础物理学中最大的谜团之一有关-为什么宇宙中的物质比反物质多？这种CP破坏是一个雄心勃勃的设施的目标，称为中微子工厂，但由于第三个角度必须大于零，才能成功测量第三个角度将是中微子振荡物理学的关键一步。T2K的工作原理是在日本东海岸的J-PARC设施中产生一束强大的μ子中微子，然后让它通过日本地下的地面传播到日本西海岸附近的一个名为Super Kamiokande的巨大地下探测器。中微子振荡会使大多数的μ子中微子变味，如果第三个角不为零，它们中的一些会变成电子中微子，这可以在超级神冈中看到。探测器将在J-PARC建造，以测量中微子束在两个设施之间传播之前的特性。联合王国将为J-PARC的这些近距离探测器提供主要元件（以及中微子束线元件）。这些近距离探测器的目的是确保我们知道束中有多少电子中微子（你不能制造纯μ子中微子束，总是有一些污染），以及有多少相互作用可能会欺骗我们认为有电子中微子，而实际上没有。为了进行实验，必须将这些近探测器测量结果与Super Kamiokande的观测结果进行比较，而本赠款中要求的RA将负责英国了解和分析Super Kamiokande数据的工作。

Over the last decade experiments throughout the world have demonstrated that the particles known as neutrinos have very different properties than was expected in the Standard Model of particle physics. In the Standard Model neutrinos come in three different kinds, called 'flavours' - electron, muon, and tau neutrinos - and these flavours are immutable. Once a neutrino is produced as one flavour it never changes. Standard Model neutrinos were also thought to have no rest mass, and therefore to always travel at the speed of light. We now know that neutrinos, in fact, have mass, and that the flavours of neutrinos can mix in a particular way we call 'neutrino oscillations' whereby a beam of one flavour of neutrino will turn into the other flavours as it propagates. The T2K experiment will make new measurements of unprecedented precision of these neutrino oscillations in the hopes of better understanding the phenomenon and also trying to understand the implications of neutrino oscillations for other areas of physics. In particular, neutrino oscillations are described by three mixing angles that effect how the different flavours mix with each other, and existing experiments have only measured two of these angles. It is the goal of T2K to observe effects arising from the third angle, and T2K should be about ten times more sensitive than existing experiments which have only set an upper limit on the size of this angle. This third angle is particularly interesting to physicists, because if it is non-zero it opens the possibility of observing violations of a symmetry called CP in neutrino oscillations. CP violation would make the oscillations of neutrino different from the oscillations of anti-neutrinos, and this effect may be related to one of the biggest mysteries in fundamental physics - why is there more matter than anti-matter in the universe? This CP violation is the target of the longer term plans for an ambitious facility called a Neutrino Factory, but since the third angle must be larger than zero for this to succeed a measurement of this third angle would be a key step forward in neutrino oscillation physics. T2K works by creating a powerful beam of muon neutrinos at the J-PARC facility on Japan's east coast and then allowing it to propagate through the ground underneath Japan to a huge underground detector called Super Kamiokande near Japan's west coast. Neutrino oscillations will make most of these muon neutrinos change flavour, and if the third angle is not zero some of them will turn into electron neutrinos which can be seen in Super Kamiokande. Detectors will be built at J-PARC to measure the properties of the neutrino beam before it propagates between the two facilities. The UK will contribute major elements of these near detectors at J-PARC (as well as elements of the neutrino beamline). The purpose of these near detectors is to make sure that we know how many electron neutrinos were in the beam to start with (you cannot make a pure muon neutrino beam, there is always some contamination) and how many interactions there are that might fool us into thinking there are electron neutrinos when there aren't. In order to perform the experiment these near detector measurements have to be compared to the observations by Super Kamiokande, and the RA requested in this grant would be in charge of the UK work on understanding and analysing the data from Super Kamiokande.