Next generation measurement of the electron electric dipole moment with heavy molecules.

重分子电子电偶极矩的下一代测量。

• 批准号: PP/D00425X/1
• 负责人: Jonathan Hudson
• 金额: $ 54.72万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=PP%2FD00425X%2F1
• 关键词: Next; generation; measurement; electron; electric

I'm doing research into the relationship between matter and antimatter. This relationship is one of the biggest mysteries in physics today. But before I get on to explaining why it's such a big mystery, I should explain a little about what antimatter is. All of the matter around us is made up of protons, neutrons and electrons. These subatomic particles combine together to make atoms, the elements, and then these atoms combine together to make everything we see around us, solid, liquid and gas. But this isn't the end of the subatomic story. As we've looked more carefully we've discovered that as well as protons, neutrons and electrons there are many more, much more elusive, subatomic particles. We've found these particles in odd places: in cosmic ray showers, some kinds of nuclear decays, and in the remnants of atoms that have been smashed in particle colliders. Physicists have tried to explain how these particles relate to one another, to bring order to the particle zoo. And they've been spectacularly succesful, coming up with a theory that is called the Standard Model. This Standard Model brings order to the hundreds of subatomic particles that we've discovered, sorting them into families with regular patterns, predicting their properties with incredible accuracy. It's one of the great triumphes of twentieth century physics. Now I can explain what antimatter is. One of the most striking features of the Standard Model is that it arranges the particles into pairs. Every particle has a partner with the opposite electrical charge called an anti-particle. These anti-particles are what we call antimatter. The Standard Model predicts that these anti-particles should obey all the same rules that normal particles do. Experiments have confirmed this, that particles and antiparticles behave in a very symmetric way. What goes for one goes for the other. This is the big mystery! If matter and antimatter obey just the same laws, if particles of matter and antimatter come in pairs, then where's all the antimatter? We would expect that there should be just as much of it as there is normal matter. But there's not. The whole world is made almost entirely of normal matter, with only tiny traces of antimatter. Astronomers have looked right to the edge of the visible universe and even then they see just matter, no great stashes of anitmatter. What happened to all the antimatter? It's this question that we are trying to answer. We hope to answer it by searching for tiny differences between the behaviour of matter and antimatter. Could these tiny differences be responsible for the near extinction of antimatter over the billions of years that the universe has been evolving? We've decided to study electrons. We can think of the electron as a little ball of electrical charge. What we do is measure whether this ball is round or not. Now, this might sound completely unrelated to the question of antimatter, but it's not. We have very strong evidence that tells us that unless electrons are _perfectly_ round, the matter and antimatter _can't_ behave in exactly the same way. So by making a very careful measurement of the electron's shape we can infer something about the nature of antimatter. All without having to make or use any actual antimatter - I think this is very elegant! So far we've checked the roundness of the electron to an incredible degree of precision: the equivalent would be measuring the diameter of the earth to better than the width of one human hair. And so far, we've seen no evidence of non-roundness. What we're planning on doing in the next few years is using some of the latest developments in atomic and molecular physics to make our experiment 1000 times more precise. With this increased precision we think we might be able to see a tiny deviation from perfect roundness and hopefully explain the mystery of the antimatter.

我在研究物质和反物质之间的关系。这种关系是当今物理学中最大的谜团之一。但在我解释为什么它是一个如此大的谜团之前，我应该解释一下什么是反物质。我们周围的所有物质都是由质子、中子和电子组成的。这些亚原子粒子联合收割机结合在一起形成原子，元素，然后这些原子联合收割机结合在一起形成我们周围的一切，固体，液体和气体。但这并不是亚原子故事的结束。当我们更仔细地观察时，我们发现除了质子、中子和电子之外，还有更多、更难以捉摸的亚原子粒子。我们在一些奇怪的地方发现了这些粒子：在宇宙射线簇射中，在某些核衰变中，在粒子对撞机中被粉碎的原子残余物中。物理学家试图解释这些粒子是如何相互关联的，以便为粒子动物园带来秩序。他们非常成功，提出了一个理论，叫做标准模型。这个标准模型为我们发现的数百种亚原子粒子带来了秩序，将它们按规则模式分类，以令人难以置信的准确度预测它们的属性。这是世纪物理学的伟大成就之一。现在我可以解释什么是反物质了。标准模型最显著的特征之一是它将粒子成对排列。每个粒子都有一个带相反电荷的伙伴，称为反粒子。这些反粒子就是我们所说的反物质。标准模型预测，这些反粒子应该遵守与正常粒子相同的规则。实验已经证实了这一点，即粒子和反粒子的行为是非常对称的。对一方有利的事对另一方也有利。这是最大的谜团！如果物质和反物质遵循同样的定律，如果物质和反物质的粒子成对出现，那么所有的反物质在哪里？我们可以预期，它的数量应该和正常物质一样多。但是没有。整个世界几乎完全由正常物质组成，只有微量的反物质。天文学家们已经看到了可见宇宙的边缘，即使这样，他们也只看到了物质，没有大量的反物质。所有的反物质都去哪了？这是我们试图回答的问题。我们希望通过寻找物质和反物质行为之间的微小差异来回答这个问题。这些微小的差异可能是宇宙进化数十亿年来反物质几乎灭绝的原因吗？我们决定研究电子。我们可以把电子看作一个带电的小球。我们所做的是测量这个球是否是圆的。现在，这听起来可能与反物质的问题完全无关，但事实并非如此。我们有非常有力的证据告诉我们，除非电子是完美的圆形，否则物质和反物质的行为不可能完全相同。所以通过仔细测量电子的形状，我们可以推断出反物质的性质。所有这些都不需要制造或使用任何实际的反物质-我认为这是非常优雅的！到目前为止，我们已经以令人难以置信的精度检查了电子的圆度：相当于测量地球的直径，比人类头发的宽度还要好。到目前为止，我们还没有看到非圆的证据。在接下来的几年里，我们计划使用原子和分子物理学的最新发展，使我们的实验精确1000倍。随着精确度的提高，我们认为我们可能能够看到与完美圆形的微小偏差，并有望解释反物质的奥秘。

项目成果

Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell

冷缓冲气体池中 YbF 分子的扩散、热化和光泵浦

• DOI: 10.1103/physreva.83.023418
• 发表时间: 2011
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Skoff S

Pulsed beams as field probes for precision measurement

脉冲束作为现场探针进行精密测量

• DOI: 10.1103/physreva.76.033410
• 发表时间: 2007
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Hudson J

Stochastic multi-channel lock-in detection

随机多通道锁定检测

• DOI: 10.1088/1367-2630/16/1/013005
• 发表时间: 2014
• 期刊: New Journal of Physics
• 影响因子: 3.3
• 作者: Hudson J

A robust floating nanoammeter.

坚固的浮动纳安表。

• DOI: 10.1063/1.3036985
• 发表时间: 2008
• 期刊: The Review of scientific instruments
• 作者: Sauer BE

Doppler-free laser spectroscopy of buffer-gas-cooled molecular radicals

缓冲气体冷却分子自由基的无多普勒激光光谱

• DOI: 10.1088/1367-2630/11/12/123026
• 发表时间: 2009
• 期刊: New Journal of Physics
• 影响因子: 3.3
• 作者: Skoff S