AN Underground Belayed In-Shaft experiment to search for long-lived particles using LHC service shafts at CERN

基本粒子物理标准模型（SM）是最深刻、最完整、最准确的科学理论，已经通过了几十年的实验测试。然而，它无法回答许多基本问题。这些问题包括：-暗物质的性质，它贡献了宇宙总质量的80%，-来自核反应的中微子的谜题，例如SM预测核反应是无质量的，但在实验中已知其质量非常小，尽管不是零质量，物质-反物质不对称的起源之谜，这将解释为什么我们所知道的宇宙是由物质而不是反物质组成的，等等。许多提出的理论方案都解决了这些基本问题，预测了新的、电中性的粒子，它们的寿命很长，可以通过典型的对撞机实验来探测，比如欧洲核子研究中心的大型强子对撞机（LHC）上的ATLAS或CMS。然而，对于这种电中性的、质量超过1千兆电子伏（GeV）的长寿命粒子，也就是比氢原子质量更大的粒子，存在着一个惊人的间隙不敏感。这种灵敏度差距在寿命中跨越了几个数量级，这意味着衰变长度从100米到大爆炸核合成界的1亿米，相当合理地假设粒子在大型强子对撞机中产生时以光速运动。该提案旨在及时缩小目前对长寿命粒子的灵敏度差距，并且比具有竞争灵敏度的提案成本低一个数量级，从而对该领域产生变革性影响。这可以通过在欧洲核子研究中心的大型强子对撞机（LHC）上安装现有的ATLAS实验服务轴来实现。预计的探测器结构，一个地下保护的井下搜索实验（ANUBIS），将由许多跟踪站组成，固定在轴内并固定在其墙壁上，用具有出色定时能力的专用跟踪探测器测量大约15,000 m^3。对于质量在1 GeV以上的电中性长寿命粒子，每个粒子的寿命比目前运行的和批准的未来实验增加了1000倍。为了经济有效地应对这一挑战，ANUBIS的跟踪站将采用下一代探测器，使用电阻板室（RPC）技术，我将在拟议的FLF项目中开发该技术，使用ANUBIS的低成本，大规模规格。除了上述雄心勃勃的研究计划之外，另一个重要目标是扩大现有ATLAS探测器的全部潜力，以便在短时间内搜索长寿命粒子。我将在拟议的FLF项目中开发的探测器技术，使用低成本，大规模规格的ANUBIS，是使用基于自然发生的宇宙射线的介子断层扫描建筑物，桥梁和其他大型基础设施的理想候选。宇宙射线层析成像与现有的方法相比具有重要的优势，这些方法的深度和分辨率有限（雷达），价格昂贵且存在严重的健康和安全风险（x射线），甚至令人望而却步（破坏性方法）。初步研究揭示了广泛的应用，考虑到1950-70年代建造的大量老化建筑和基础设施的结构完整性存在问题。以安全的方式延长现有结构的使用时间，可以大大减少人类的环境足迹，再加上节省大量费用，将极大地造福社会。FLF提案的主要目标之一是实现宇宙射线断层扫描的全尺寸演示原型，包括现场测试，中期目标是商业化。

The Standard Model of Elementary Particle Physics (SM) is the deepest, mostcomplete and accurate scientific theory and has passed decades of experimentaltests. Yet, it cannot answer many fundamental questions. These include:- the nature of Dark Matter, which contributes 80% of the total mass in the Universe, - the puzzle of neutrino particles from e.g. nuclear reactions that are predicted to be massless by the SM but are experimentally known to have a very small albeit non-zero mass, and - the riddle of the origin of the matter-antimatter asymmetry that would explain why the Universe -- as we know it -- is composed of matter rather than antimatter,- etc.Many proposed theoretical scenarios that address these fundamental questionspredict new, electrically neutral particles with long lifetimes on the scalethat can be probed by typical collider experiments like ATLAS or CMS at theLarge Hadron Collider (LHC) of CERN. Yet, there is a striking gap insensitivity for such long-lived particles that are electrically neutral andhave a mass above 1 Gigaelectronvolt (GeV), i.e., are more massive than ahydrogen atom. This sensitivity gap spans several orders of magnitude in thelifetimes, which translates into decay lengths from 100 m and up to theBig-Bang nucleosynthesis bound of 100,000,000 m, quite reasonably assuming theparticles move at the speed of light when produced at the LHC.This proposal aims to close the present gap in sensitivity to long-livedparticles in a timely manner and at up to one order of magnitude lower coststhan proposals with competing sensitivity, resulting in a transformative impacton the field. This can be achieved by instrumenting the existing service shaftsof the ATLAS experiment at the Large Hadron Collider (LHC) of CERN. Theforeseen detector structure, AN Underground Belayed In-Shaft search experiment(ANUBIS), will consist of a number of tracking stations belayed into the shaftand affixed to its walls, instrumenting approximately 15,000 m^3 with dedicatedtracking detectors with excellent timing capability. For scenarios withelectrically neutral long-lived particles with masses above 1 GeV, the lifetimereach is increased by a factor of up to 1,000 compared to currently operatingand approved future experiments. To master this challenge cost-effectively,the tracking stations of ANUBIS will employ the next generation of detectorsusing the resistive plate chamber (RPC) technology that I will develop in theproposed FLF project using the low-cost, large-scale specifications of ANUBIS. In addition to the ambitious research programme above, another importantobjective is to expand the full potential of the existing ATLAS detector tosearch for long-lived particles on a short time scale. The detector technology that I will develop in the proposed FLF project usingthe low-cost, large-scale specifications of ANUBIS is an ideal candidate forthe scanning of buildings, bridges, and other large-scale infrastructure usingmuon tomography based on naturally occurring cosmic rays. Cosmic ray tomographyprovides crucial advantages over currently available approaches that sufferfrom a limited depth reach and resolution (radar), are expensive and carrysignificant health and safety risks (X-ray), or even prohibitive (destructivemethods). Preliminary research reveals a wide range of applications, given thelarge number of ageing buildings and infrastructure constructed in the 1950-70swith questionable structural integrity. The environmental human footprint canbe dramatically reduced by using existing structures for longer in a safemanner, which, combined with substantial cost savings, will enormously benefitour society. One of the main goals of the FLF proposal is to realise afull-scale demonstrator prototype for cosmic ray tomography including fieldtests, with an intermediate-term goal of commercialisation.