Development of 3He magnetometer for ultra-sensitive measurements of high magnetic fields in Penning traps

高精度的质量测量现在的目标是达到一个相对质量的不确定度优于10-11的基本相互作用和对称性的测试。通常在潘宁阱中通过测量存储离子的自由空间回旋频率来确定质量，假设磁场以类似的精度已知。然而，标准的核磁共振方法无法以如此高的精度测量磁场。我们的方法（建议）是基于测量的自由感应衰变的气体，核自旋极化3 He后，共振射频脉冲激发。其要点是在大于4特斯拉的典型潘宁阱场中，可以得到核自旋极化~ 3 He的几分钟的相干自旋进动时间。从测量的拉莫尔频率（> 100 MHz），可以确定样品自旋上的局部磁场，精度优于10-11。这种装置可以小型化，以适合旁边的潘宁陷阱，允许超灵敏的磁场监测和测量磁场梯度（梯度计）。3 He气体是自旋极化原位使用一种新的，非标准的变体的亚稳态交换光泵浦。

High precision mass measurements nowadays aim to reach a relative mass uncertainty better than 10-11 for tests of fundamental interactions and symmetries. The mass is usually determined in Penning traps via the measurement of the free-space cyclotron frequency of the stored ions assuming the magnetic field is known with similar accuracy. Standard nuclear magnetic resonance methods, however, fail to measure the field with such high accuracy. Our approach (proposal) is based on the measurement of the free induction decay of gaseous, nuclear spin-polarized 3He after a resonant radio-frequency pulse excitation. The essential point is that coherent spin-precession times of several minutes for nuclear spin-polarized 3He can be obtained in typical Penning trap fields of > 4 Tesla. From the measured Larmor frequency (> 100 MHz) the local magnetic field across the sample spins can be determined to an accuracy of better than 10-11. Such a device can be miniaturized to fit next to a Penning trap that allows ultra-sensitive magnetic field monitoring and measurements of magnetic field gradients (gradiometer). The 3He gas is spin-polarized in-situ using a new, non-standard variant of the metastability exchange optical pumping.