The DiRAC 2.5x Facility

天文学、核物理和粒子物理学界的物理学家们都专注于理解宇宙在非常基础的层面上是如何运作的。他们工作的距离尺度变化了50个数量级，从大型强子对撞机实验探测的最小距离，原子核深处，到太空中发现的最大尺度星系团。然而，科学挑战是通过诸如宇宙是如何开始的以及它是如何演变的问题联系在一起的。宇宙的基本组成和结构是什么，它们是如何相互作用的？进步需要新的天文观测和实验数据，但也需要新的理论见解。理论理解越来越多地来自大规模计算，这使我们能够非常准确地用数据来面对我们理论的后果，或者让我们能够详细地询问数据，以提取对我们理论有影响的信息。这些计算测试了我们拥有的最快的计算机，并推动了这一领域的技术边界。他们还提供了一个良好的环境，培养学生在国家的最先进的技术，代码优化和数据挖掘和可视化。DiRAC 2 HPC设施自2012年以来一直在运行，为STFC支持的粒子物理，天文学，宇宙学和核物理的所有领域的理论研究提供计算资源。它是一个高生产力的设施，每年在国际同行评审期刊上发表250多篇论文。然而，DiRAC 2硬件现在至少有5年的历史，因此存在重大故障风险。任何一项DiRAC 2服务的丢失都将对依赖它来提供科学研究的研究社区产生潜在的灾难性影响。DiRAC 2.5x项目所需资金的主要目的是更换达勒姆、爱丁堡和莱斯特老化的DiRAC 2硬件，同时利用最近的硬件进步来提供一些新功能（例如使用闪存的i/o加速）作为拟议DiRAC 3服务的原型。DiRAC 2.5x建立在DiRAC HPC设施的成功基础上，并将在2018年期间提供支持STFC支持的所有科学领域的尖端研究所需的资源。虽然需要资金来“保持照明”，但科学计划将继续保持世界领先。将从这项投资中受益的项目包括：（一）根据第一原理对基本粒子的性质进行晶格量子色动力学计算;（二）通过提高对涉及物质基本成分（称为夸克）的罕见过程的理论预测的准确性，提高欧洲核子研究中心大型强子对撞机实验发现新物理学的潜力;（iii）模拟产生引力波的成对黑洞的合并，例如LIGO集团最近发现的引力波;（iv）迄今为止对宇宙中星系的形成和演化进行的最逼真的模拟;（v）气体在超大质量黑洞上的吸积，这是从物质中提取能量的最有效方法，也是驱动星系形成和演化的引擎;（vi）利用欧洲航天局GAIA卫星的新数据校准我们银河系的新模型;（七）太阳内部和行星内部的详细模拟;（八）星团中恒星的形成-这将首次有可能跟踪质量比太阳大许多倍的恒星的形成。

hysicists across the astronomy, nuclear and particle physics communities are focussed on understanding how the Universe works at a very fundamental level. The distance scales with which they work vary by 50 orders of magnitude from the smallest distances probed by experiments at the Large Hadron Collider, deep within the atomic nucleus, to the largest scale galaxy clusters discovered out in space. The Science challenges, however, are linked through questions such as: How did the Universe begin and how is it evolving? and What are the fundamental constituents and fabric of the Universe and how do they interact?Progress requires new astronomical observations and experimental data but also new theoretical insights. Theoretical understanding comes increasingly from large-scale computations that allow us to confront the consequences of our theories very accurately with the data or allow us to interrogate the data in detail to extract information that has impact on our theories. These computations test the fastest computers that we have and push the boundaries of technology in this sector. They also provide an excellent environment for training students in state-of-the-art techniques for code optimisation and data mining and visualisation. The DiRAC2 HPC facility has been operating since 2012, providing computing resources for theoretical researchin all areas of particle physics, astronomy, cosmology and nuclear physics supported by STFC. It is a highly productivefacility, generating more than 250 papers annually in international, peer-reviewed journals. However, the DiRAC2 hardware is now at least 5 years old and is therefore at significant risk of failure. The loss of any one of the DiRAC2 serviceswould have a potentially disastrous impact on the research communities which rely on it to deliver their scientific research. The main purpose of the requested funding for the DiRAC2.5x project is to replace the ageing DiRAC2 hardware at Durham, Edinburgh and Leicesterwhile taking advantage of recent hardware advances to provide some new capabilities (e.g. i/o acceleration using flash storage) as prototypes forthe proposed DiRAC3 services. DiRAC2.5x builds on the success of the DiRAC HPC facility and will provide the resources needed to support cutting-edge research during 2018 in all areas of science supported by STFC. While the funding is required to "keep the lights on", the science programme will continue to beworld-leading. Examples of the projects which will benefit from this investment include:(i) lattice quantum chromodynamics (QCD) calculations of the properties of fundamental particles from first principles;(ii) improving the potential of experiments at CERN's Large Hadron Collider for discovery of new physics by increasing the accuracy of theoretical predictions for rare processes involving the fundamental constituents of matter known as quarks; (iii) simulations of the merger of pairs of black holes which generate gravitational waves such as those recently discovered by the LIGO consortium;(iv) the most realistic simulations to date of the formation and evolution of galaxies in the Universe;(v) the accretion of gas onto supermassive black holes, the most efficient means of extracting energy from matter and the engine which drives galaxy formation and evolution;(vi) new models of our own Milky Way galaxy calibrated using new data from the European Space Agency's GAIA satellite;(vii) detailed simulations of the interior of the sun and of planetary interiors;(viii) the formation of stars in clusters - for the first time it will be possible to follow the formation of stars many times more massive than the sun.