Capital funding for CTA-UK programme

宇宙中充满了能量极高的粒子，它们的运动速度非常接近光速。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。这些粒子的路径很难追踪，但它们可以通过产生伽马射线来揭示它们的存在。和低能射线x射线一样，伽马射线不能穿透地球大气层，通常用卫星望远镜来探测。然而，在非常高的能量（VHE）下，伽马射线是非常罕见的，用宇宙飞船探测到它们是不可能的——它们击中一个合理大小的卫星的机会太小了。幸运的是，我们可以从地面上观察到它们，通过蓝光的闪光，切伦科夫辐射，它们在大气中相互作用时产生。切伦科夫辐射的光芒比星光微弱1万倍，所以需要望远镜来观察它，而且由于闪光只持续几十亿分之一秒，所以需要超高速相机来记录它们。从目前的地面伽玛射线望远镜，如HESS，我们知道有大量的现象可以用伽玛射线来研究。VHE伽马射线望远镜已经探测到超新星爆炸的遗迹、双星系统、遥远星系中黑洞产生的高能粒子喷流、恒星形成区和许多其他物体。这些观测不仅可以帮助我们了解这些物体内部发生了什么，还可以回答与暗物质和时空本身的本质有关的基本物理学问题。然而，我们现在已经达到了现有仪器的极限，因此来自全球29个国家的约1000名科学家聚集在一起建造了一种新仪器——切伦科夫望远镜阵列（CTA）。CTA将大大提高现有仪器的灵敏度，并将观测到的伽马射线范围扩展到低能量和高能量。据预测，已知的VHE发射天体的目录将从已知的130个扩展到1000多个，我们可以期待在天体物理学和基础物理研究的关键领域有许多新的发现。为了实现我们对CTA的宽能量范围要求，需要建造三种不同尺寸的望远镜：直径4米的小型望远镜（SSTs）、12米的中型望远镜（MSTs）和23米的大型望远镜（LSTs）。CTA将由两个望远镜阵列组成，一个在北半球，一个在南半球。北阵将包括4个lst和20个mst。南部阵列将包含类似数量的大型和中型望远镜，但增加了70个sst的广泛阵列，专门用于研究可以优先从南半球观测到的最高能量现象。SSTs将探测到有史以来最高能量的光子，其能量接近1千兆电子伏特，每个光子的能量是x射线的1万亿倍。CTA望远镜的原型目前正在生产中，预计将于2016年开始全面建设。目前有11所英国大学参与了CTA。英国各集团正把精力集中在建造sst上。我们已经生产了一种创新的双镜SST设计，现在正在巴黎埃菲尔铁塔的视线内建造。在本提案中，我们请求资金进一步开发我们为该望远镜设计的相机，并支持英国工业开发它所需的反射镜。

The Universe is full of particles with such high energies that they are travelling at very close to the speed of light. Theseparticles play a significant role in many areas of astrophysics, from the life-cycles of stars to the evolution of galaxies.The paths of these particles are hard to trace, but they 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 detectthem. However, at very high energies (VHE), gamma rays are extremely rare, and detecting them using spacecraft becomesimpossible - the chance they would hit a reasonably sized satellite is just too small. Luckily, it is possible to observe them from the ground via the flashes of blue light, Cherenkov radiation, they produce when they interact in the atmosphere. The glow of this Cherenkov radiation is 10,000 times fainter than starlight, so telescopes are needed to observe 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 bestudied using gamma rays. VHE gamma ray telescopes have detected the remains of supernova explosions, binary star systems, highly energetic jets of particles produced by black holes in distant galaxies, star formation regions, and many other objects. Theseobservations can help us to understand not only what is going on inside these objects, but also answer fundamental physics 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 about 1000 scientists from 29 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 extend the 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: 4 m diameter small-sized telescopes (SSTs), 12 m medium-sized telescopes (MSTs) and 23 m large-sized telescopes (LSTs). CTA will consist of two arrays of telescopes, one in the northern hemisphere and one in the southern hemisphere. The northern array will consist of 4 LSTs and 20 MSTs. The southern array will contain similar numbers of large and medium sized telescopes, but add to them an extensive array of 70 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 approaching a peta-electronvolt, each a thousand billion times more energetic than an X-ray. Production of prototype CTA telescopes in now underway, with full-scale construction of the arrays expected to start in 2016.There are currently 11 UK universities involved in CTA. The UK groups are concentrating their efforts on the construction ofthe SSTs. We have already produced an innovative dual-mirror SST design, which is now being built in sight of the Eiffel Tower inParis. In this proposal we request funds to further develop the camera we have designed for this telescope and to support development by UK industry of the mirrors needed for it.