Fundamental Symmetry Tests with Trapped Antihydrogen: ALPHA at CERN/AD

这笔拨款将支持加拿大对基于cern的ALPHA协作的科学计划的贡献。ALPHA的目标是尽可能精确地测量反氢原子的性质，并将它们与普通氢原子的性质进行比较。这些比较可以作为物质和反物质之间基本对称性的测试，并有望揭示一些物理学中尚未解决的最大问题。ALPHA合作项目由来自7个国家15个机构的约50名科学家组成。其中超过三分之一的人来自加拿大的研究实验室和大学（统称为ALPHA-Canada），并将得到这笔资金的支持。自2005年ALPHA合作成立以来，ALPHA- canada一直由NSERC资助，并在ALPHA的许多最重要的成就中发挥了主导作用。由NSERC资助推动的早期高调里程碑的例子包括：中性反物质的稳定（Nature 2010）和长期（Nature Physics 2011）捕获，微波光谱原理证明（Nature 2012）和电荷中性测试（Nature Communications 2014和Nature 2016）。在最近的三年资助周期中，我们在反氢物理领域取得了显著进展。特别是，新设备（ALPHA-2）的建造和调试使我们能够从所谓的“原理证明”演示过渡到精确物理的健壮程序。自我们上次向NSERC提交SAP项目拨款申请（2016年10月）以来，取得的科学里程碑的例子包括：观察激光诱导的反氢中的双光子1S-2S跃迁（Nature 2017），以及随后对该跃迁频率的2万亿分之一测量（Nature 2018）；对反氢的地面超精细光谱的观测（Nature 2017），以及随后对该转变频率的百万分之九的测量（Nature，正在审查中）；观察反氢中的1S-2P Lyman-alpha跃迁（Nature 2018），以及随后对精细结构和Lamb位移的测量（Nature，正在审查中）；反氢的激光冷却和随后的激光冷却反氢的1S-2S光谱（手稿正在准备中）。除此之外，我们还开发并建造了另一种反氢装置：ALPHA-g。ALPHA-g的目的是使实验能够探测反氢和地球之间的引力相互作用，从而在反物质领域首次直接测试爱因斯坦的等效原理。ALPHA-Canada已经、正在并将在ALPHA-g计划的大多数方面发挥主导作用。在此申请中，我们要求资助一个令人兴奋的、高度可见的三年活动计划，该计划将显著推进反氢原子精确基本对称测试的前沿。

This grant will support Canadian contributions to the scientific program of the CERN-based ALPHA Collaboration. The goal of ALPHA is to measure properties of the antihydrogen atom to the highest precision possible, and to compare them to those of the ordinary hydrogen atom. These comparisons serve as tests of fundamental symmetries between matter and antimatter, and are expected to shed light on issues that rank amongst some of the greatest unsolved problems in physics. The ALPHA Collaboration comprises approximately 50 scientists from 15 institutions in 7 countries. More than a third of those individuals come from Canadian research laboratories and universities (collectively called ALPHA-Canada), and will be supported by this grant. ALPHA-Canada has been funded by NSERC continuously since the ALPHA Collaboration was formed in 2005, and has played leading roles in many of ALPHA's most significant accomplishments. Examples of earlier high-profile milestones driven by NSERC funding include: stable (Nature 2010) and long term (Nature Physics 2011) trapping of neutral antimatter, proof of principle microwave spectroscopy (Nature 2012), and tests of charge neutrality (Nature Communications 2014 and Nature 2016). During the tenure of our most recent three-year funding cycle, we dramatically advanced the field of antihydrogen physics. In particular, construction and commissioning of a new apparatus (ALPHA-2) enabled us to transition from what one might call "proof-of-principle" demonstrations to a robust program of precision physics. Examples of scientific milestones attained since our last SAP Project Grant application was submitted to NSERC (October 2016) include: observation of laser-induced two-photon 1S-2S transitions in antihydrogen (Nature 2017), and a subsequent 2 part-per-trillion measurement of the frequency of that transition (Nature 2018); observation of the ground hyperfine spectrum of antihydrogen (Nature 2017), and a subsequent 9 part-per-million measurement of the frequency of that transition (Nature, under review); observation of the 1S-2P Lyman-alpha transition in antihydrogen (Nature 2018), and a subsequent measurement of the fine structure and Lamb shift (Nature, under review); and laser-cooling of antihydrogen and subsequent 1S-2S spectroscopy of laser-cooled antihydrogen (manuscripts under preparation). Further to this, we have developed and constructed yet another antihydrogen apparatus: ALPHA-g. The purpose of ALPHA-g is to enable experiments that will probe the gravitational interaction between antihydrogen and the Earth, yielding a first direct test of Einstein's Equivalence Principle in the antimatter sector. ALPHA-Canada has, is, and will play leading roles most aspects of the ALPHA-g program. In this application, we request funding to support and exciting and highly visible three-year program of activities that will significantly advance the frontiers of precision fundamental symmetry tests with antihydrogen atoms.