Oxford development work for Compact High-Energy Camera for the Cherenkov Telescope Arrey

宇宙中充满了能量如此之高的粒子，它们以非常接近光速的速度行进。这些粒子在天体物理学的许多领域发挥着重要作用，从恒星的生命周期到星系的演化。这些粒子很难追踪，但可以通过产生伽马射线来揭示它们的存在。像较低能量的X射线一样，伽马射线不会穿透地球大气层，通常使用基于卫星的望远镜来探测它们。然而，在非常高的能量(VHE)下，伽马射线非常少，从航天器上探测它们是不可能的。幸运的是，通过它们在大气中引发的级联产生的蓝光闪光切伦科夫辐射，有可能从地面探测到它们。切伦科夫辐射在大气中发出的光芒比星光弱一万倍，因此需要大镜子来收集它，而且由于闪光的持续时间只有几十亿分之一秒，所以需要超高速相机来记录它们。我们从目前的地面伽马射线望远镜(如Hess)中了解到，有大量的现象需要研究。伽马射线望远镜探测到了超新星爆炸、双星系统、遥远星系中黑洞产生的高能喷流、恒星形成区域和许多其他天体的残骸。这些观测不仅可以帮助我们了解这些物体内部发生的事情，还可以回答与暗物质和时空本身的性质有关的基本物理问题。然而，我们现在已经达到了现有仪器所能完成的极限，因此来自世界25个国家的约800名科学家聚集在一起，建造了一台新的仪器-切伦科夫望远镜阵列(CTA)。CTA将提供比现有仪器更高的灵敏度，并将观测到的伽马射线的能量范围扩大到更低和更高的能量。据预测，已知的VHE发射天体将从130个扩大到1000多个，在天体物理和基础物理研究的关键领域可以期待许多新的发现。为了实现CTA所需的宽能量范围，有必要建造三种不同尺寸的望远镜：直径约5米的小型望远镜(SST)，约12米的中型望远镜(MST)和约23米的大尺寸望远镜(LST)。CTA将由两个望远镜阵列组成，一个在北半球，一个在南半球。北方阵列可能由大约4个LST和大约20个MST组成。南部阵列将包含类似数量的大型和中型望远镜，但增加了约50个SST的广泛阵列，专门用于研究优先从南半球观察到的最高能量现象。SST将探测到有史以来能量最高的光子，能量接近Peta电子伏特，每个光子的能量都是X射线的1万亿倍。CTA目前正处于筹备阶段，我们预计2015年开始建设。目前有11所英国大学参与了CTA。英国集团正集中力量建设SST。我们已经生产了一种创新的双镜SST设计，它将建在巴黎埃菲尔铁塔的视线范围内。在这项提案中，我们请求资金来做几件事。首先，我们要搭建并测试一台双镜SST相机的样机，以及一个标定系统。其次，我们将利用我们在计算机模拟方面的专业知识来优化SST的设计和整体阵列布局。第三，我们将为CTA开发数据分析技术，以确保英国科学家能够在第一台望远镜开始运行后立即分析CTA的数据。最后，几名英国团队成员在CTA担任领导角色，我们正在申请资金支持这些人，使我们能够出差参加相关会议。

The Universe is full of particles with such high-energies that they are travelling at very close to the speed of light. These particles play a significant role in many areas of astrophysics, from the life-cycles of stars to the evolution of galaxies. These particles are hard to trace, but can reveal their presence by producing gamma rays. Like their lower-energy cousins, X-rays, gamma rays do not penetrate the Earth's atmosphere and usually satellite-based telescopes are used to detect them. However, at very high energies (VHE) there are very few gamma rays, and detecting them from spacecraft becomes impossible. Luckily, it is possible to detect them from the ground via the flashes of blue light, Cherenkov radiation, produced by the cascades they initiate in the atmosphere. The glow from Cherenkov radiation in the atmosphere is 10,000 times fainter than starlight, so large mirrors are required to collect it, and because the flashes last only a few billionths of a second, ultra-fast cameras are needed to record them.We know from current ground-based gamma-ray telescopes such as HESS that there is a wealth of phenomena to be studied. VHE gamma ray telescopes have detected the remains of supernova explosions, binary star systems, highly energetic jets produced by black holes in distant galaxies, star formation regions, and many other objects. These observations can help us to understand not only what is going on inside these objects, but also answer fundamental physics questions relating to the nature of dark matter and of space-time itself. However, we have now reached the limit of what can be done with current instruments, and so ~800 scientists from 25 countries around the world have come together to build a new instrument - the Cherenkov Telescope Array (CTA). CTA will offer a dramatic increase in sensitivity over current instruments, and extends the energy range of the gamma rays observed to both lower and higher energies. It is predicted that the catalogue of known VHE emitting objects will expand from the 130 known to over 1000, and we can expect many new discoveries in key areas of astrophysics and fundamental physics research.To achieve the wide energy range we require of CTA, it is necessary to build telescopes of three different sizes: ~5 m diameter small-sized telescopes (SSTs), ~12 m medium-sized telescopes (MSTs) and ~23 m large-sized telescope (LST). CTA will consist of two arrays of telescopes, one in the northern hemisphere and one in the southern hemisphere. The northern array will likely consist of 4 or so LSTs, and around 20 MSTs. The southern array will contain similar numbers of large and medium telescopes, but add to them an extensive array of ~50 SSTs, specifically to investigate the highest- energy phenomena which can be observed preferentially from the southern hemisphere. The SSTs will detect the highest energy photons ever seen, with energies approach a peta-electronvolt, each a thousand billion times more energetic than an X-ray. CTA is currently in its preparatory phase, and we expect construction to start in 2015.There are currently 11 UK universities involved in CTA. The UK groups are concentrating their efforts on the construction of the SSTs. We have already produced an innovative dual-mirror SST design, which will be built in sight of the Eiffel Tower in Paris. In this proposal we request funds to do several things. Firstly, we want to build and test a prototype dual-mirror SST camera, together with a calibration system. Secondly, we will use our expertise in computer simulations to optimise the design of the SSTs and the overall array layout. Thirdly, we will develop data analysis techniques for CTA, to ensure that UK scientists are able to analyse the data from CTA as soon as the first telescopes start operation. Finally, several UK team members have leadership roles in CTA and we are requesting funds to support these people and enable us to travel to the relevant meetings.