Measurement of the sign of the magnetic moment for unstable nuclei using newly developed rotating radio-frequency field system

Abstract Nuclear magnetic moment (μ) measurements provide useful information on nuclear structures. For unstable nuclei, nuclear magnetic resonance (NMR) of in-beam polarized nuclei with beta asymmetry detection (β-NMR) is a powerful method to determine μ. In this method, the sign of μ can be determined using rotating radio-frequency (RF) fields. In this article, we developed a new system to apply rotating RF fields that can produce almost complete circular rotation, compared to that in previous systems. Using this system, we successfully determined the sign of μ for 29P and 25Al. For both nuclei, the sign of μ is positive, which is consistent with the predictions of the single particle shell model. This article details the new rotating RF field system.