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Physics with Trapped Antihydrogen

俘获反氢物理学

基本信息

批准号：
EP/L014718/1
负责人：
Mike Charlton
金额：
$ 75.24万
依托单位：
Swansea University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FL014718%2F1
关键词：
Physics Trapped Antihydrogen

项目摘要

Understanding the origin and evolution of our Universe has been at the heart of scientific endeavour for centuries. Recent decades have seen major advances, as physics and cosmology have combined to produce the beginnings of a coherent picture. Our Universe seems to have been born in a cataclysmic event called the Big Bang, and has continuously evolved over the 13-14 billion years since then. Though much of the visible Universe can be explained, there are still many profound mysteries, including the existence of antimatter, and its fate.Simply put, antimatter is an enigma. Whilst the symmetry of the laws of physics, and in particular quantum mechanics, predict its existence on a more-or-less equal footing to matter, the Universe appears to be composed only of the latter. Addressing this conundrum is one of the great challenges of basic science. As the Universe cooled after the Big Bang it appears that all the antimatter vanished, but leaving a tiny excess (one part in a billion) of matter from which the entire material Universe is created. The problem is we don't understand how this came to be. There are asymmetries in the behaviour of matter and antimatter, but they are too small by many orders of magnitude to account for the existence of matter in the Universe. One way to address this problem, and the way we have chosen, is to study antihydrogen - an atom that the Universe never got the chance to make - and compare its properties with those of hydrogen. Recently, we have made great progress. We are now able to gently mix antiprotons and positrons to create some antihydrogen atoms with low enough kinetic energies to be held in a magnetic minimum neutral atom trap that is only 0.54 K deep. This trap is formed by magnetic fields from a complicated coil arrangement that forms the field minimum in the centre of the antihydrogen production region. Antihydrogen, like hydrogen, has a tiny magnetic moment - think of the orbiting positron as a tiny current loop - such that the energy levels shift in an applied magnetic field. Those atoms whose potential energy increases in the field will prefer to sit at the magnetic field minimum, and may be trapped. We have been able to confine anti-atoms for 15 minutes or more if required, so we are sure that they are in their ground state.In a landmark experiment we have performed the first ever study of an anti-atom by bombarding the trapped antihydrogen with microwave radiation. The frequency of the microwaves was tuned to a resonant transition that forced the anti-atoms into a quantum state that could not be held in the trap. The result was that the trap was emptied of the antihydrogen - but only when the microwave frequency was set appropriately. We were able to tell that our trap had been emptied, and also spot the annihilations as the antihydrogen hit the trap walls. We are currently re-building our apparatus to improve this experiment, and also to use lasers to address the spectrum of antihydrogen. Although this capability has great opportunities, there is much work to be done before the properties of hydrogen and antihydrogen can be compared with precision. In this project we will start in this direction. If any differences are found, we will have discovered new physics, and perhaps come some way along the road to discovering the fate of antimatter in the early Universe.

几个世纪以来，了解宇宙的起源和演化一直是科学研究的核心。近几十年来，随着物理学和宇宙学的结合产生了一幅连贯图景的开端，我们看到了重大进展。我们的宇宙似乎诞生于一次被称为大爆炸的灾难性事件中，并在此后的130 - 140亿年里不断进化。尽管可见宇宙的大部分都可以解释，但仍有许多深奥的谜团，包括反物质的存在及其命运。简单地说，反物质是一个谜。虽然物理定律的对称性，特别是量子力学，预言了它与物质的存在或多或少是平等的，但宇宙似乎只由后者组成。解决这个难题是基础科学面临的巨大挑战之一。随着宇宙在大爆炸后冷却，似乎所有的反物质都消失了，但留下了一小部分多余的物质（十亿分之一），整个物质宇宙就是由这些物质形成的。问题是我们不明白这是怎么来的。物质和反物质的行为是不对称的，但它们太小了许多数量级，不足以解释宇宙中物质的存在。解决这个问题的一种方法，也是我们选择的方法，是研究反氢——一种宇宙从未有机会制造的原子——并将其性质与氢的性质进行比较。最近，我们取得了很大的进展。我们现在能够温和地混合反质子和正电子来产生一些反氢原子，它们的动能足够低，可以被保存在只有0.54 K深的磁性最小中性原子阱中。这个陷阱是由一个复杂的线圈排列形成的磁场形成的，这个线圈在反氢产生区域的中心形成了最小的磁场。反氢，像氢一样，有一个微小的磁矩——把轨道上的正电子想象成一个微小的电流环——这样在外加磁场中能级就会发生变化。那些在磁场中势能增加的原子会倾向于坐在磁场最小的位置，并可能被困住。如果需要的话，我们已经能够将反原子限制在15分钟或更长时间内，所以我们确信它们处于基态。在一项具有里程碑意义的实验中，我们首次对反原子进行了研究，方法是用微波辐射轰击被捕获的反氢原子。微波的频率被调谐到共振跃迁，迫使反原子进入一种不能被困在陷阱里的量子态。结果是，只有在适当设置微波频率的情况下，陷阱才会被清空反氢。我们能够判断出我们的陷阱已经被清空，并且还能发现反氢撞击陷阱壁时发生的湮灭。我们目前正在重建我们的设备，以改进这个实验，并使用激光来处理反氢的光谱。虽然这种能力有很大的机会，但在氢和反氢的性质可以与精度相比较之前，还有很多工作要做。在这个项目中，我们将从这个方向开始。如果发现任何差异，我们将发现新的物理学，也许在发现早期宇宙中反物质的命运的道路上走了一段路。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Antihydrogen accumulation for fundamental symmetry tests.

DOI：
10.1038/s41467-017-00760-9
发表时间：
2017-09-25
期刊：
Nature communications
影响因子：
16.6
作者：
Ahmadi M;Alves BXR;Baker CJ;Bertsche W;Butler E;Capra A;Carruth C;Cesar CL;Charlton M;Cohen S;Collister R;Eriksson S;Evans A;Evetts N;Fajans J;Friesen T;Fujiwara MC;Gill DR;Gutierrez A;Hangst JS;Hardy WN;Hayden ME;Isaac CA;Ishida A;Johnson MA;Jones SA;Jonsell S;Kurchaninov L;Madsen N;Mathers M;Maxwell D;McKenna JTK;Menary S;Michan JM;Momose T;Munich JJ;Nolan P;Olchanski K;Olin A;Pusa P;Rasmussen CØ;Robicheaux F;Sacramento RL;Sameed M;Sarid E;Silveira DM;Stracka S;Stutter G;So C;Tharp TD;Thompson JE;Thompson RI;van der Werf DP;Wurtele JS
通讯作者：
Wurtele JS

An experimental limit on the charge of antihydrogen.

DOI：
10.1038/ncomms4955
发表时间：
2014-06-03
期刊：
Nature communications
影响因子：
16.6
作者：
Amole C;Ashkezari MD;Baquero-Ruiz M;Bertsche W;Butler E;Capra A;Cesar CL;Charlton M;Eriksson S;Fajans J;Friesen T;Fujiwara MC;Gill DR;Gutierrez A;Hangst JS;Hardy WN;Hayden ME;Isaac CA;Jonsell S;Kurchaninov L;Little A;Madsen N;McKenna JT;Menary S;Napoli SC;Nolan P;Olchanski K;Olin A;Povilus A;Pusa P;Rasmussen CØ;Robicheaux F;Sarid E;Silveira DM;So C;Tharp TD;Thompson RI;van der Werf DP;Vendeiro Z;Wurtele JS;Zhmoginov AI;Charman AE
通讯作者：
Charman AE

Limit on the electric charge of antihydrogen

反氢电荷的限制