Search

We report on the operation of co-located ${}^{129}$Xe and ${}^{131}$Xe nuclear spin masers with an external feedback scheme, and discuss the use of ${}^{131}$Xe as a comagnetometer in measurements of the ${}^{129}$Xe spin precession frequency. By applying a correction based on the observed change in the ${}^{131}$Xe frequency, the frequency instability due to magnetic field and cell temperature drifts are eliminated by two orders of magnitude. The frequency precision of 6.2 $\mu$Hz is obtained for a 10$^4$ s averaging time, suggesting the possibility of future improvement to $\approx$ 1 nHz by improving the signal-to-noise ratio of the observation., Comment: 8 pages, 5 figures

Exotic nuclei are characterized by a number of neutrons (or protons) in excess relative to stable nuclei. Their shell structure, which represents single-particle motion in a nucleus, may vary due to nuclear force and excess neutrons, in a phenomenon called shell evolution. This effect could be counterbalanced by collective modes causing deformations of the nuclear surface. Here, we study the interplay between shell evolution and shape deformation by focusing on the magnetic moment of an isomeric state of the neutron-rich nucleus 75Cu. We measure the magnetic moment using highly spin-controlled rare-isotope beams and achieving large spin alignment via a two-step reaction scheme that incorporates an angular-momentum-selecting nucleon removal. By combining our experiments with numerical simulations of many-fermion correlations, we find that the low-lying states in 75Cu are, to a large extent, of single-particle nature on top of a correlated 74Ni core. We elucidate the crucial role of shell evolution even in the presence of the collective mode, and within the same framework, we consider whether and how the double magicity of the 78Ni nucleus is restored, which is also of keen interest from the perspective of nucleosynthesis in explosive stellar processes., 10 pages, 4 figures

We search for 129Xe EDM by using an active nuclear spin maser. In this experiment, the amplitude of the maser oscillation signal is one of the most important parameters that eventually determine the frequency precision. The amplitude is proportional to the ratio of the transverse spin relaxation time T 2 to the effective longitudinal spin relaxation time $T_{1}^{\ast }$ . In particular, for a spin maser of 3He (a co-magnetometer) for which $T_{1}^{\ast }$ typically reaches ∼50 h, a long T 2 is needed. T 2 depends on the homogeneity of the magnetic field which is applied with coils in order to keep the spins under precession. In the present report, we discuss on the design and construction of a new coil which provided a root-mean square (rms) field gradient of less than 5.0 μG/cm. The result of the field measurement has shown that the field gradient in the cell fulfills the target condition $\sqrt {\langle {(\nabla B_{z})^{2}} \rangle }

Co-magnetometry enables the elimination of systematic errors arising from the long-term drift in the magnetic field, and is essential for a precision measurement of spin precession frequency in experiments searching for electric dipole moment (EDM). $^{131}$Xe nuclear spin maser shows great promise as a co-magnetometer in a Xe EDM experiment, because the systematic error originating from the Xe-Rb interaction, which virtually limits the sensitivity in a case of a $^3$He co-magnetometer, will be cancelled out. The performance of a cell which contains both $^{129}$Xe and $^{131}$Xe was investigated. In the best cell among those fabricated this time, the signal-to-noise ratio in a free induction decay experiment turned out to be large enough for the operation as co-existing $^{129}$Xe-$^{131}$Xe masers.