Magnetometry at the fTesla-scale for neutron EDM experiments using a co-habiting Xenon magnetometer based on free spin precession

新型中子EDM实验，如Paul Scherrer研究所（PSI）的国际中子EDM合作，旨在达到≈10-28 ecm的测量灵敏度，与目前中子电偶极矩（nEDM）的上限dn < 3 × 10-26 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200s的典型拉姆齐周期内达到1 fT灵敏度水平的磁强计。在这个建议中，我们集中在氙磁强计的发展，应该能够监测和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≈10±26ecm，是由众所周知的vxe场与磁场梯度的相互作用产生的，并产生了与电场线性的频移，模拟了nEDM。这种频移可以用分离振荡场的拉姆齐方法来测量。自旋极化氙由光泵浦产生，在nEDM光谱仪的超冷中子（UCN）存储体积内监测核自旋（共居原子氙磁强计）的自由进动。

Novel neutron EDM experiments, like the international neutron EDM collaboration at the Paul Scherrer Institute (PSI) aim to reach a measurement sensitivity of ≈ 10-28 ecm, a two orders of magnitude improvement compared to the present upper limit of dn < 3 x 10-26 e∙cm for the neutron electric dipole moment (nEDM). In order to reach this ambitious goal, magnetometry reaching the 1 fT sensitivity level during a typical Ramsey cycle of 200s is demanded. In this proposal we concentrate on the development of a Xenon magnetometer which should be able to monitor and correct geometric phase induced false nEDM effects. These false effects, which set the present systematic limit of dn, false ≈ 10-26ecm, result from the interaction of the well known vxE-field with magnetic field gradients and produce a frequency shift linear to the electric field mimicking an nEDM. This frequency shift can be measured using the Ramsey method of separated oscillatory fields. Spin-polarized Xenon is produced by optical pumping and the free precession of nuclear spins (co-habiting atomic Xenon magnetometer) is monitored within the ultracold neutron (UCN) storage volume of the nEDM spectrometer.