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

PanEDM的目标是利用格勒诺布尔劳厄-朗之万研究所(ILL)的SuperSUN超冷中子源，在第一级测量中子的电偶极矩，预计灵敏度高达dN=2x10-27ecm。在前面的DFG项目中，我们可以将实验转移到ILL，并在源上设置它，使其硬件适应源的特定需求，并重新调试其组件。UCN源安装现已接近完成，已放置在束流位置，并在现场进行了低温调试。随着最后一个部件目前正在插入，UCN的生产预计将在即将到来的(第三个)反应堆周期中开始，该反应堆将于2021年在ILL。虽然PanEDM项目最终的目标是灵敏度远远超过10-27ECM，但该提议涵盖了实验的第一阶段：在这里，我们使用了过去十年制造的设备，该设备采用了Ramsey的分离振荡场和室温下两个UCN陷阱的技术。在这个项目的过程中，信号源将在期间分阶段进行升级，目标是最终直接提供极化UCN。有了这一点，UCN的数量也将大幅增加。这进而需要不断地推进PanEDM设备以匹配变化的条件。因此，在反应堆周期之间的中断期间，将在没有SuperSUN的情况下实施和测试更新的部件，并使用反应堆周期来表征设备和获取EDM数据。该项目的其中一个方面是改进磁场特性，以保证在第一阶段没有共磁力仪的情况下性能足够。此外，磁力测量将相应地得到增强。此外，我们还与UCN一起调试了PANEDM设备。随着SuperSUN在2021年投入使用，我们计划在现场测试UCN光学元件和探测器，并在与源共享空间可用后安装HV单元。我们将进行实际的EDM测量和分析。我们还开发新的表面和组件来推动PanEDM：随着更好的解决方案问世，我们正在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提供的具有磁存储的更硬频谱。最后，需要一个超导偏振器磁铁。这将显著提高全息电火花加工的性能，因为它减少了由于去极化和箔片传输和表面相互作用造成的传输和传输损耗。最重要的是，它需要匹配来自SuperSUN的更难的光谱和磁存储，在那里，箔片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，并在TUM保持UCN物理领域的专业知识，因为慕尼黑FRM-II反应堆的UCN源几年后才能使用。

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.