The search for the electric dipole moment of the neutron with the PanEDM experiment - continuation proposal

PanEDM的目标是在第一阶段测量中子的电偶极矩，预计灵敏度高达dn = 2x10-27 ecm，使用格勒诺布尔Laue-Langevin研究所（ILL）的超级太阳超冷中子源（UCN）。在之前的DFG项目中，我们可以将实验移至il并在源端进行设置，调整其硬件以适应源端的特定需求并重新调试其组件。UCN源装置现在接近完成，放置在光束位置，并在现场进行低温调试。随着最后一批组件的插入，预计将于2021年在ILL即将到来的（第三个）反应堆周期开始生产UCN。虽然PanEDM项目的最终目标是灵敏度远远超过10-27 ecm，但该提案涵盖了实验的第一阶段：在这里，我们使用了过去十年建造的设备，该设备部署了拉姆齐的分离振荡场技术和室温下的两个UCN陷阱。在这个项目的过程中，源将分阶段升级，最终目标是直接提供极化UCN。因此，UCN的数量也将大量增加。这反过来又要求PanEDM设备不断进步，以适应不断变化的条件。因此，在没有SuperSUN的情况下，在反应堆循环之间的休息期间，更新的组件将被实施和测试，并且反应堆循环用于表征设备并获取EDM数据。在项目的几个方面中，有一个是对磁场特性的改进，以保证在一期无共磁仪的情况下，其性能是足够的，磁强学也将相应加强。此外，我们将PanEDM设备委托给UCN。随着SuperSUN在2021年投入使用，我们计划在现场测试UCN光学器件和探测器，并在与光源共享空间可用后安装高压单元。我们将进行实际的电火花加工测量并进行分析。我们还开发新的表面和组件来推进PanEDM：随着更好的解决方案的出现，我们不断升级现有的运输和存储解决方案，例如含氟聚合物涂层，我们还将开发和实施涂层和组件，以匹配SuperSUN提供的硬光谱与磁存储。最后，提出了超导极化磁体的设计要求。这将大大提高PanEDM的性能，因为减少了由于去极化、箔传输和表面相互作用造成的传输和传输损失。最重要的是，它需要与来自SuperSUN的硬光谱与磁存储相匹配，在那里，箔偏振器中的磁场不再足够。我们的项目还用于教育学生进行nEDM测量，并保持TUM UCN物理领域的专业知识，因为慕尼黑FRM-II反应堆的UCN源在未来几年内将无法使用。

PanEDM aims to measure the electric dipole moment of the neutron with a projected sensitivity of up to dn = 2x10-27 ecm in its first stage, using the SuperSUN source of ultra-cold neutrons (UCN) at the Institute Laue-Langevin (ILL) in Grenoble. In a preceding DFG project we could move the experiment to ILL and set it up at the source, adapt its hardware to the specific needs of the source and re-commission its components. The UCN source installation is now close to completion, placed at the beam position and cryogenically commissioned at the site. With last components currently being inserted, begin of UCN production is expected in the oncoming (third) reactor cycle at ILL in 2021. While the PanEDM project ultimately targets for a sensitivity well beyond 10-27 ecm, this proposal covers the first phase of the experiment: Here we use an apparatus built over the last decade, which deploys Ramsey’s technique of separated oscillating fields and two UCN traps at room temperature. In the course of this project, the source will be upgraded in stages during, with the goal to ultimately provide polarized UCN directly. With this, also the number of UCN will be massively increased. This in turn requires the PanEDM apparatus to be continuously advanced to match the varying conditions. Thus, during breaks between reactor cycles updated components will be implemented and tested without SuperSUN, and the reactor cycles are used to characterize the apparatus and take EDM data. Among the aspects of the project is the improvement of magnetic field characterization to guarantee that the performance is sufficient for no co-magnetometer in phase I. Also, magnetometry will be enhanced accordingly. Further, we commission the PanEDM apparatus with UCN. With SuperSUN being operational in 2021, we plan to test the UCN optics and detectors in situ, install the HV unit after the shared space with the source becomes available. We will carry out actual EDM measurements and perform analysis. We also develop new surfaces and components to advance PanEDM: While we are continuously upgrading existing solutions for transport and storage as better solutions become available, e.g. fluoropolymer coatings, we will also develop and implement coatings and components to match the harder spectrum delivered by SuperSUN with magnetic storage. Finally, a superconducting polarizer magnet is requested. This will significantly enhance the performance of PanEDM due to the reduction of transport and transmission losses due to depolarization and foil transmission and surface interactions. Most importantly it is needed to match the harder spectrum from SuperSUN with magnetic storage, where the magnetic field in foil polarizers is not sufficient any more. Our project also serves for the education of students for nEDM measurements and to maintain expertise in the field of UCN physics at TUM, as the UCN source at the FRM-II reactor in Munich will not be available for another few years.