CTA Pre-production Phase Extension 2020

宇宙中充满了能量巨大的粒子，它们以非常接近光速的速度运动。它们在很多方面影响着宇宙，影响着恒星的生命周期和星系的演化。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。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，在极高能量（VHE）下，伽马射线非常少，用航天器探测它们是不可能的。幸运的是，在地面上可以通过它们在大气中相互作用时产生的蓝光（切伦科夫辐射）来观察它们。大气中切伦科夫辐射发出的光比星光微弱1万倍，所以需要大型镜子来收集它，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需要研究。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射流、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问题。然而，我们已经达到了现有仪器的极限，因此来自世界33个国家的1640多名科学家和工程师聚集在一起建造了一种新的仪器——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的能量范围扩展到更低和更高的值。据预测，已知的VHE发射物体的目录将从目前已知的大约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学的关键领域有许多新的发现。为了实现CTA的能量覆盖，需要三种不同尺寸的望远镜：小型（直径~4米）、中型（12米）和大型（23米）望远镜（分别为SSTs、MSTs和LSTs）。CTA将在北半球和南半球设置阵列。北阵将包括4个lst和25个mst。南部阵列将在其4个lst和25个mst的基础上增加一个由70个sst组成的广泛阵列，以研究主要在南部天空可见的最高能量现象。我们预计CTA南部地区的第一批望远镜将于2021年开始建造。目前有12所英国大学和实验室参与了CTA。开发硬件的四个英国小组正在集中精力建造sst，我们之前为其开发了紧凑型高能相机（CHEC）。最近，CHEC和意大利应科院的望远镜结构从三个竞争的SST设计中被选中，作为最终SST设计的基础。在2020年的资助期内，我们将利用从CHEC学到的经验，为SST设计和生产最终的生产摄像机。这将涉及对CHEC设计进行必要的更改，以提高可制造性、操作、维护和可靠性，最大限度地提高性能，并降低成本。2020年将进行的研究工作包括：机械设计修改、冷却改进、新的窗户和盖子设计、更新传感器、降低功耗和改进电子元件。我们也会准备AIV设备，为生产做准备。这将得到正在进行的相机软件和模拟开发的支持。我们将扩大外联活动，包括天文馆展览和英国科学会议，并加强项目管理和产品保证，为生产做好准备。

The Universe is full of particles with energies so great that they are travelling at very close to the speed of light. They affect the Universe in many ways, influencing the life cycles of stars and 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 so few gamma rays that detecting them using spacecraft becomes impossible. Luckily, it is possible to observe them from the ground via the flashes of blue light, Cherenkov radiation, produced when they interact 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 reached the limit of what can be done with current instruments, and so over 1640 scientists and engineers from 33 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 energy range of the gamma rays observed to both lower and higher values. It is predicted that the catalogue of known VHE emitting objects will expand from the roughly 130 known now to over 1000, and we can expect many new discoveries in key areas of astrophysics and fundamental physics. To achieve the energy coverage of CTA, telescopes of three different sizes are needed: Small (~4 m diameter), Medium (12 m) and Large (23 m) Sized Telescopes (SSTs, MSTs and LSTs, respectively). CTA will have arrays in the northern and southern hemispheres. The northern array will consist of 4 LSTs and 25 MSTs. The southern array will add to its 4 LSTs and 25 MSTs an extensive array of 70 SSTs, to investigate the highest energy phenomena, visible mainly in the southern sky. We expect construction of the first telescopes on the CTA southern site to begin in 2021.There are currently 12 UK universities and Laboratories involved in CTA. The four UK groups developing the hardware are concentrating their efforts on the construction of the SSTs for which we previously developed the Compact High Energy Camera (CHEC). CHEC has been recently selected along with the Italian ASTRI telescope structure, from the three competing SST designs, as the basis for the final SST design. During the 2020 funding period we will use the lessons learned from CHEC to design and produce a final production-ready camera for SST. This will involve making essential changes from the CHEC design to improve manufacturability, operation, maintenance and reliability, maximise performance, and cut costs. The research work to be undertaken in 2020 includes: mechanical design modifications, improvements to cooling, a new window and lid design, updated sensors, reduced power consumption, and improvements to electronics components. We will also prepare AIV facilities in preparation for production. This will be supported by ongoing camera software and simulations development. We will expand outreach activities to include a planetarium show and UK science meeting and enhance project management and product assurance in readiness for production.