Precision field characterization for the next generation measurement of the neutron EDM

在这个方案中，我们计划实现一个磁场测量系统的下一代测量中子的电偶极矩（EDM）的灵敏度为10-28 ecm。该系统将用于两个目的：（i）在安装期间和每个组件在其最终位置之后，离线表征磁稳定环境内的磁场线圈和组件的各种磁场。这对于EDM腔室部件、UCN光学器件和真空腔室内的硬件尤为重要。的污染的大小的品质因数是最大的1 pT在3厘米的距离内的组件，从而引起几何相位效应。目标（ii）是在线EDM测量期间的磁场测量。这里，每个传感器在100 fT水平上的长期性能和在10-4 rad倾斜水平上的场方向分辨率是必要的。这有助于在实验操作时使用矢量信息跟踪来自大的和小的局部源的梯度形状的变化。由于所有其他原位（共同）磁力计仅提供平均信息，这对于理解系统效应至关重要。为此，我们使用全光学Cs磁力计系统进行了测试，该系统非常适合在线和离线原位测量，而不会因感应RF或磁化硬件组件而产生噪声。在这个项目中，我们想在3个后续阶段为这两个目标开发一套这样的探头。第1阶段是进一步优化传感器及其操作模式，第2阶段是在现场安装更大的传感器组，用于离线和在线现场映射以及调试，第3阶段是针对其他系统的操作、表征和测试。

In this proposal we plan to realize a magnetic field measurement system for a next generation measurement of the neutron's electric dipole moment (EDM) with a sensitivity of 10-28 ecm. The system will be deployed for two purposes: (i) characterization of all kinds of fields from field coils and components inside the magnetically stabilized environment offline during installation and after of each component at their final location. This is in particular important for the EDM chamber parts, UCN optics and hardware inside the vacuum chamber. The figure of merit for the magnitude of contaminations is maximum 1 pT at 3 cm distance for inner components, giving rise to geometric phase effects. Goal (ii) is the measurement of magnetic fields during the EDM measurement online. Here, the long-term performance on a 100 fT level per sensor and the resolution of field direction on the 10-4 rad tilt-level is necessary. This helps to track changes of the shape of gradients from large and small localized sources using vector information while the experiment is operating. As all other in-situ (co-)magnetometers only provide averaged information, this is critical for the understanding of systematic effects. For this purpose we made tests with a fully optical Cs magnetometer system that is perfectly suitable for in-situ measurements online and offline without producing noise due to induced RF or magnetized hardware components. Within this project we would like to develop a set of such probes for both goals in 3 subsequent stages. Stage 1 is further optimization of sensors and their operation modes, stage 2 is the installation of a larger set of sensors on site for offline and online field mapping with commissioning and stage 3 is the operation, characterization and test against other systems.