The DiRAC 2.5x Facility

天文学、核物理学和粒子物理学领域的物理学家都致力于从非常基本的层面上理解宇宙的运作方式。从原子核深处的大型强子对撞机实验探测到的最小距离，到在太空中发现的最大规模的星系团，他们工作的距离尺度相差50个数量级。然而，科学挑战通过以下问题联系在一起：宇宙是如何开始的，它是如何演变的？宇宙的基本组成和结构是什么？它们是如何相互作用的？要取得进展，不仅需要新的天文观测和实验数据，还需要新的理论见解。对理论的理解越来越多地来自大规模计算，这些计算使我们能够非常准确地用数据来面对我们理论的后果，或者允许我们详细询问数据，以提取对我们的理论产生影响的信息。这些计算测试了我们拥有的最快的计算机，并推动了该领域的技术界限。它们还为培训学生学习最先进的代码优化、数据挖掘和可视化技术提供了一个极好的环境。DiRAC2 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、宇宙学和核物理所有领域的理论研究提供计算资源。它是一个高生产率的机构，每年在国际同行评议的期刊上发表超过250篇论文。然而，DiRAC2硬件现在至少已有5年的历史，因此面临着极大的故障风险。失去任何一项DiRAC2服务，都将对依赖它进行科学研究的研究界产生潜在的灾难性影响。为DiRAC2.5x项目申请资金的主要目的是更换老化的DiRAC2，同时利用最近的硬件进步提供一些新的能力(例如，使用闪存加速I/O)，作为拟议的DiRAC3服务的原型。DIRAC2.5x建立在DIRAC HPC设施的成功基础上，并将在2018年提供所需资源，以支持STFC支持的所有科学领域的尖端研究。虽然需要资金来“保持灯火通明”，但该科学计划将继续处于世界领先地位。将从这项投资中受益的项目的例子包括：(I)格子量子色动力学(QCD)从第一原理计算基本粒子的性质；(Ii)通过提高对涉及夸克物质的基本成分的罕见过程的理论预测的准确性，改善欧洲核子研究中心的大型强子对撞机实验发现新物理的潜力；(Iii)模拟产生引力波的两个黑洞的合并，如LIGO财团最近发现的那些；(Iv)迄今为止对宇宙中星系形成和演化的最现实模拟；(V)超大质量黑洞吸收气体，这是从物质中提取能量的最有效手段，也是驱动星系形成和演化的引擎；(Vi)我们所在的银河系的新模型，使用欧洲航天局的GAIA卫星的新数据进行了校准；(Vii)对太阳内部和行星内部的详细模拟；()恒星以星团形式形成--首次有可能跟踪质量比太阳大许多倍的恒星的形成过程。

Physicists 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 research in all areas of particle physics, astronomy, cosmology and nuclear physics supported by STFC. It is a highly productive facility, 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 services would 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 while taking advantage of recent hardware advances to provide some new capabilities (e.g. i/o acceleration using flash storage) as prototypes for the 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 be world-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.