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

PanEDM的目标是测量中子的电偶极矩，其第一阶段的灵敏度高达dn = 2x 10 -27 ecm，使用格勒诺布尔劳厄-朗之万研究所（ILL）的SuperSUN超冷中子源（UCN）。在之前的DFG项目中，我们可以将实验转移到ILL并在源代码处进行设置，使其硬件适应源代码的特定需求并重新调试其组件。UCN源安装现已接近完成，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，UCN的生产预计将于2021年在ILL即将到来的（第三）反应堆循环中开始。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Ramsey的分离振荡场技术和两个室温下的UCN陷阱。在这个项目的过程中，源将在期间分阶段升级，目标是最终直接提供极化UCN。因此，UCN的数量也将大幅增加。这又要求PanEDM设备连续前进以匹配变化的条件。因此，在反应堆循环之间的间歇期间，将在没有SuperSUN的情况下实施和测试更新的组件，并且反应堆循环用于表征装置并获取EDM数据。该项目的一个方面是改进磁场特性，以保证性能足以在第一阶段不使用共磁强计。此外，磁力测定也将相应加强。此外，我们委托PanEDM设备与UCN。随着超级太阳在2021年投入运行，我们计划在原地测试UCN光学器件和探测器，并在与源共享的空间可用后安装HV单元。我们将进行实际的EDM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提供的更硬的光谱与磁存储。最后，要求超导极化磁体。这将显着提高PanEDM的性能，由于减少的传输和传输损耗，由于去极化和箔传输和表面相互作用。最重要的是，需要将SuperSUN的更硬光谱与磁存储相匹配，其中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在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.