Precision Experiments with Antihydrogen

反氢精密实验

• 批准号: EP/V00137X/1
• 负责人: Niels Madsen
• 金额: $ 447.55万
• 依托单位: Swansea University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FV00137X%2F1
• 关键词: Precision; Experiments; Antihydrogen

The observation that the particulate Universe is currently comprised mostly of matter seems unequivocal, as does the assertion that at its birth, the Universe contained equal amounts of matter and antimatter. Just why this imbalance, or asymmetry, has evolved is currently not understood, and indeed it is one of the central questions of physics beyond what is known as the Standard Model. The conventional approach to experimentally explore symmetry in fundamental physics is to study particle collisions at ever-higher kinetic energies, in an effort to reproduce conditions further back towards the beginning of the Universe (the Big Bang). It is becoming increasingly clear, though, that such investigations can be complemented and enriched via small scale experiments, for instance in setting limits on particle electric dipole moments, with novel dark matter searches and, as here, in precision comparisons of the properties of matter and antimatter.We have chosen to bring the powerful toolbox developed via the physics of atom trapping and cooling and atomic spectroscopy to bear on this problem. In short, we create, capture and then cool antihydrogen atoms before studying their properties and behaviour. In one set of experiments (ALPHA-III, which will be devoted to spectroscopic investigations) we intend to systematically probe the transition between the ground state of the anti-atom and its first excited state using a technique known as two-photon Doppler-free spectroscopy. We hope to determine its frequency with a precision similar to that currently achieved for the hydrogen atom, for which it is known to a staggering 14 decimal places. This will deliver a very direct test of symmetry. We have already measured the same transition in antihydrogen to 12 decimal places and we are now aiming for the hydrogen precision. Additionally, we intend to determine fundamental constants in anti-atoms, such as the anti-Rydberg constant and the antiproton charge radius, by combining the ground-to-first excited state work with spectroscopic measurements of additional transitions.In our second major experimental avenue, so-called ALPHA-g, we will analyse the trajectories of antihydrogen atoms as they leave a purpose-built atom trap whose magnetic fields have been carefully tailored to enhance experimental sensitivity to the gravitational behaviour of the anti-atom. We expect to make the first determination of the acceleration of antimatter due to gravity. Eventually we hope to extract the value of g for antihydrogen to an accuracy of 1% or better. Interest in the behaviour of gravity on (anti-)atomic systems stems in part from another puzzle of modern physics, namely that our theory of gravity (Einstein's General Relativity) is incompatible with currently accepted quantum field theories. And whilst the equivalence principle dictates that all objects, irrespective of their content (e.g., in this context independently of whether they are comprised of matter or antimatter), should fall with the same acceleration towards the Earth, testing the (classical) theory of gravity on quantum objects is of fundamental interest. Electrically neutral antimatter-systems are preferable, since they are immune to the influence of electric fields, which can swamp the effects of gravity for charged particles, and antihydrogen is particularly suitable, since it can now be trapped and cooled.Thus, our two-pronged attack on symmetry and gravity by exploring the physics of antihydrogen promises the development of new insights into nature. Our ability to pin down the properties and behaviour of anti-objects is unprecedented, and we aim to further develop this with the work set out in this proposal. Any difference between matter and antimatter, however small, will have profound consequences for our understanding of physics and the laws of nature.

微粒宇宙目前主要由物质组成的观察结果似乎是明确的，正如宇宙诞生时包含等量的物质和反物质的断言一样。为什么这种不平衡或不对称会进化，目前还不清楚，事实上，它是物理学的核心问题之一，超越了所谓的标准模型。在实验上探索基础物理学对称性的传统方法是研究更高动能的粒子碰撞，努力重现宇宙起源（大爆炸）的条件。然而，越来越清楚的是，这样的研究可以通过小规模的实验来补充和丰富，例如，设定粒子电偶极矩的限制，用新的暗物质搜索，以及像这里一样，精确比较物质和反物质的性质。我们选择利用原子捕获、冷却和原子光谱学等物理技术开发的强大工具箱来解决这个问题。简而言之，在研究反氢原子的性质和行为之前，我们先创造、捕获并冷却它们。在一组实验（ALPHA-III，将专门用于光谱研究）中，我们打算使用一种称为双光子无多普勒光谱的技术系统地探测反原子基态和第一激发态之间的转变。我们希望以类似于目前对氢原子所达到的精度来确定它的频率，对氢原子的频率已知到令人震惊的小数点后14位。这将提供一个非常直接的对称测试。我们已经在反氢中测量了同样的跃迁，到小数点后12位，我们现在的目标是氢的精度。此外，我们打算通过结合从地到第一激发态的工作和额外跃迁的光谱测量来确定反原子中的基本常数，如反里德伯常数和反质子电荷半径。在我们的第二个主要实验途径，即所谓的ALPHA-g中，我们将分析反氢原子离开一个专门建造的原子陷阱时的轨迹，该陷阱的磁场经过精心设计，以提高对反原子引力行为的实验灵敏度。我们期望第一次确定反物质因重力而加速。最终，我们希望将反氢的g值提取到1%或更高的精度。对（反）原子系统的引力行为的兴趣部分源于现代物理学的另一个难题，即我们的引力理论（爱因斯坦的广义相对论）与目前公认的量子场论不相容。虽然等效原理规定，所有物体，无论其内容如何（例如，在这种情况下，无论它们是由物质还是反物质组成），都应该以相同的加速度落向地球，但在量子物体上测试（经典的）引力理论具有根本的意义。电中性的反物质系统是更可取的，因为它们不受电场的影响，电场可以淹没带电粒子的重力效应，而反氢特别合适，因为它现在可以被捕获和冷却。因此，我们通过探索反氢的物理性质，对对称性和引力进行双管齐下的研究，有望对自然产生新的见解。我们确定反物体的性质和行为的能力是前所未有的，我们的目标是通过本提案中列出的工作进一步发展这一点。物质和反物质之间的任何差异，无论多么微小，都会对我们对物理学和自然规律的理解产生深远的影响。

项目成果

On the formation of antihydrogen beams using travelling optical lattices

利用行进光学晶格形成反氢束

• DOI: 10.1088/1367-2630/ac0b7b
• 发表时间: 2021
• 期刊: New Journal of Physics
• 影响因子: 3.3
• 作者: Madsen N

Design and performance of a novel low energy multispecies beamline for an antihydrogen experiment

• DOI: 10.1103/physrevaccelbeams.26.040101
• 发表时间: 2023-04-21
• 期刊: PHYSICAL REVIEW ACCELERATORS AND BEAMS
• 影响因子: 1.7
• 作者: Baker, C. J.;Bertsche, W.;Wurtele, J. S.
• 通讯作者: Wurtele, J. S.

Measurements of Penning-Malmberg trap patch potentials and associated performance degradation

• DOI: 10.1103/physrevresearch.6.l012008
• 发表时间: 2024-01
• 期刊: Physical Review Research
• 影响因子: 4.2
• 作者: C. J. Baker;W. Bertsche;A. Capra;C. L. Cesar;M. Charlton;A. Christensen;R. Collister;A. Cridland Mathad;S. Eriksson;A. Evans;N. Evetts;J. Fajans;T. Friesen;M. Fujiwara;D. Gill;P. Grandemange;P. Granum;J. Hangst;M. Hayden;D. Hodgkinson;E. Hunter;C. A. Isaac;M. A. Johnson;J. Jones;S. A. Jones;S. Jonsell;A. Khramov;L. Kurchaninov;H. Landsberger;N. Madsen;D. Maxwell;J. McKenna;S. Menary;T. Momose;P. Mullan;J. Munich;K. Olchanski;A. Olin;J. Peszka;A. Powell;P. Pusa;C. Rasmussen;F. Robicheaux;R. Sacramento;M. Sameed;E. Sarid;D. M. Silveira;C. So;G. Stutter;T. Tharp;R. Thompson;C. Torkzaban;D. P. van der Werf;E. Ward;J. Wurtele