Search for the electric dipole moment of the neutron

电偶极矩（EDM）测量是粒子物理标准模型（SM）之外最重要的物理学研究之一。EDM是一个基本系统的属性，它在SM中是被禁止的，但应该存在于描述SM之外的物理的大多数可能模型中。在能量分辨率为10-22 eV的情况下，寻找该参数的实验是有史以来最精确的测量之一。由于其相对简单的组成，中子的电火花加工是一个非常突出的系统，已经排除或限制了许多新的物理模型。在我们的新实验中，我们的目标是获得比目前技术水平更好的灵敏度。在慢中子物理schwerpunktprogram中，我们已经准备了一种仪器，以提高灵敏度来测量中子的EDM。该装置是同类设备中的第一个，为控制最关键的系统效应提供了独特的可能性。虽然该仪器放置在frm - 2，但它是便携式和模块化建造的，这也是考虑到在frm - 2的UCN源的长时间延迟。2016年春天，劳-朗格万研究所（ILL）向国际呼吁在目前最强的UCN源的增强版本上进行旗舰实验。我们的设备赢得了这场比赛，这使我们能够执行一个高度竞争的实验，通过结合最好的系统控制和最强的现有UCN源。我们的目标是在本提案中对低10-27 ecm制度的灵敏度提高一个数量级以上。我们的项目计划以最有效的方式使用SPP项目的投资：我们计划(i)调整我们的设备以适应伊利诺伊大学新的UCN源。我们计划只对现有的硬件做一些小的调整；（ii）将电火花加工设备的部分硬件从第二阶段移至第二阶段，将其安装在新的波束位置，并在新的环境中操作；（iii）用UCN表征仪器的性能，并进行电火花加工测量。（iv）与此同时，我们继续在TUM的外部磁屏蔽进行研发，准备，测试和教育目的。保持在TUM这样的环境下工作的能力是很重要的，我们对提案中列出的具体项目有明确的关注，我们的长期合作伙伴PTB也在本周提交了一份提案，这与我们的提案密切相关。我们知道我们不会在这个项目中完成EDM运行，但我们可以在这个提案的范围内实际地进行竞争性测量。以这一建议为基础的长期战略还涉及卢瑟福实验室提供的硬件的重大可能更新，从而为同时涉及ILL和FRM-II的长期战略提供各种选择。

Electric dipole moments (EDM) measurements are among the most important searches for physics beyond the standard model of particle physics (SM). An EDM is a property of a fundamental system, which is forbidden in the SM, but should be present in most possible models describing physics beyond the SM. With an energy resolution of 10-22 eV, the experiments searching for this parameter are among the most precise measurements ever performed. Due to its comparably simple composition, the EDM of the neutron is a very prominent system and has already ruled out or restricted many new-physics models. With our new experiment we aim to achieve a significantly better sensitivity compared to the state of the art.Within the Schwerpunktprogramm on slow neutron physics, we have prepared an apparatus to measure the EDM of the neutron with enhanced sensitivity. The apparatus is the first of its kind, providing a unique possibility to control the most critical systematic effects. Although the apparatus is placed at the FRM-II, it has been built portable and modular, also in view of the long delays of the UCN source at the FRM-II.In spring 2016, the Institut Laue-Langevin (ILL) made an international call for a flagship-experiment at the enhanced version of the currently strongest existing UCN source. Our apparatus won this competition, which enables us to perform a highly competitive experiment, by combining the best control of systematics with the strongest existing UCN source. We aim for a more-than-one order of magnitude improvement of the sensitivity to the low 10-27 ecm regime within this proposal.Our project plans to use the investments from the SPP program in the most efficient way: we plan to (i) adapt our apparatus for the new UCN source at ILL. We plan to make only minor adaptations to the existing hardware; (ii) move part of the hardware of the EDM apparatus from FRM-II to ILL, set it up at the new beam position and operate it in the new environment; (iii) characterize the performance of the apparatus with UCN and perform EDM measurements. (iv) In parallel we continue to work at TUM with the outer magnetic shield for R&D, preparation, test and education purpose. Maintaining the capability for work in such an environment at TUM is important and we have a well-defined focus on specific items listed in the proposal, enhanced by our long-term partner PTB, who submit a proposal also in this week, which is closely linked to our proposal.We are aware that we will not finish the EDM runs within this project, but we can realistically perform a competitive measurement within the scope of this proposal. The long-term strategy, which is based on this proposal, also involves major possible updates of the hardware, provided by Rutherford Lab, enabling various options for a long-term strategy involving ILL and FRM-II simultaneously.