Magnetometry at the fTesla-scale for neutron EDM experiments

新型中子EDM实验，如Paul Scherrer研究所（PSI）的国际中子EDM合作或FRM-II的nEDM合作，旨在达到≈10-28 e∙cm的测量灵敏度，与目前中子EDM的上限dn< 3x10-26 e∙cm相比，提高了两个数量级。为了实现这一雄心勃勃的目标，需要在200秒的典型拉姆齐周期内达到fTesla灵敏度水平的磁强计。在本提案中，我们集中于现有的3He磁力计的调试和运行，该磁力计基于对气态，核极化3He样品的自由自旋进动的检测，并且应该能够在ft水平上监测磁场波动并纠正几何相位引起的假nEDM效应。这些假效应设定了目前的系统极限dn，假值≈10-26 ecm，这是由相对论性e场与现有磁场梯度的相互作用造成的，引起了与模拟nEDM的电场线性的频移。

Novel neutron EDM experiments, like the international neutron EDM collaboration at the Paul Scherrer Institute (PSI) or the nEDM collaboration at FRM-II aim to reach a measurement sensitivity of ≈10-28 e∙cm, a two orders of magnitude improvement compared to the present upper limit of dn< 3x10-26 e∙cm for the neutron EDM. In order to reach this ambitious goal, magnetometry reaching the fTesla sensitivity level during a typical Ramsey cycle of 200 s is demanded. In this proposal we concentrate on the commissioning and operation of an existing 3He magnetometer which is based on the detection of free spin-precession of gaseous, nuclear polarized 3He samples and which should be able to monitor magnetic field fluctuations at the fT-level and to correct geometric phase induced false nEDM effects. These false effects set the present systematic limit of dn, false ≈10-26 ecm and result from the interplay of the relativistic xE-field with existing magnetic field gradients causing a frequency shift linear to the electric field mimicking an nEDM.