Pickup coil optimization for polarized He-3 system

摘要

Not only can polarized He-3 gas work as neutron spin filters (NSF) but also search for spin-dependent new interactions beyond the standard model. For both cases, the relative polarization of the spin polarized noble gas needs to be measured precisely. Various NMR techniques are applied practically to monitor the He-3 cell's polarization. In this work, we tried to optimize the pickup coil for the spin exchange optical pump (SEOP) based He-3 system. By optimizing the signal-to-noise ratio (SNR), we found that the coil should be wound by thin wire for a higher number of turns. The optimized sizes of the pickup coils depend on the detailed configurations. For a spherical He-3 cell with radius a, we found the optimized coil radius is , where d is the coil to cell surface distance. For a cylindrical He-3 cell with height h, for the configurations where the coils were placed either along or perpendicular to the longitudinal axis of the target cell, we derived the optimized sizes for the specific configurations. We believe these results are practically useful for designing pickup coils of polarized He-3 systems.