Masato Tsuchiya

Search for electric dipole moment in 129Xe atom using a nuclear spin oscillator

We aim to measure the electric dipole moment (EDM) of a diamagnetic atom 129Xe using an optical-detection nuclear spin maser technique. The relation of EDM in a diamagnetic atom to nuclear Schiff moment and fundamental sources generating it is discussed, and the present status for the development of our experimental setup is presented.

Nuclear Spin Maser at Highly Stabilized Low Magnetic Field and Search for Atomic EDM

A nuclear spin maser is operated at a low static field through an active feedback scheme based on an optical nuclear spin detection and succeeding spin control by a transverse field application. The frequency stability of this optical‐coupling spin maser is improved by installation of a low‐noise current source for a solenoid magnet producing a static magnetic field in the maser operation. Experimental devices for application of the maser to EDM experiment are being developed.

Development of co-located 129 Xe and 131 Xe nuclear spin masers with external feedback scheme

We report on the operation of co-located Xe and Xe nuclear spin masers with an external feedback scheme, and discuss the use of Xe as a comagnetometer in measurements of the Xe spin precession frequency. By applying a correction based on the observed change in the 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 μHz is obtained for a 10 s averaging time, suggesting the possibility of future improvement to ≈ 1 nHz by improving the signal-to-noise ratio of the observation.

Magnetic field stabilization for Xe-129 EDM search experiment

Magnetic field stabilization is a crucial condition parameter for many kinds of ultra-high precision measurements such as a search for an electric dipole moment (EDM). The instability of magnetic field strength often arises from the drift of current flow in a solenoid coil to generate the magnetic field. For our EDM search experiment with maser oscillating diamagnetic 129Xe atoms, we have developed a new stabilized current source based on a feedback system which is devised to correct the amount of current flow measured precisely with high-precision digital multimeter and standard resistor. Using this new current source, we have successfully reduced the drifts of coil current by at least a factor of 100 compared to commercially available current sources.

Magnetic Field Stabilization for 129Xe EDM Search Experiment

Magnetic field stabilization is a crucial condition parameter for many kinds of ultra-high precision measurements such as a search for an electric dipole moment (EDM). The instability of magnetic field strength often arises from the drift of current flow in a solenoid coil to generate the magnetic field. For our EDM search experiment with maser oscillating diamagnetic 129Xe atoms, we have developed a new stabilized current source based on a feedback system which is devised to correct the amount of current flow measured precisely with high-precision digital multimeter and standard resistor. Using this new current source, we have successfully reduced the drifts of coil current by at least a factor of 100 compared to commercially available current sources.

Production of spin-aligned RI beam via two-step fragmentation with dispersion matching

To produce a radioactive-isotope (RI) beam with high spin alignment, we have developed a novel method, the two-step projectile-fragmentation (PF) method, that employs momentum-dispersion matching. An on-line experiment to produce 32A1 from 48Ca via 33A1 was performed at RIKEN RI Beam Factory. In the experiment, we succeeded in producing approximately 8% spin alignment in an RI beam of 32A1. In this paper, we focus on evaluating the magnitude of spin alignment realized in one-nucleon removal from 33A1.

Search for an EDM in diamagnetic atom 129Xe with nuclear spin maser technique

Present status of the development of a nuclear spin maser for a 129Xe atomic EDM search is reported. We studied the frequency behavior of the spin maser presently under operation, and found that the drift in the frequency is correlated with the maser amplitude drift. Also, a high-voltage application system for the 129Xe precession cell was constructed. The leakage current measured is at present on the level of nA when a high voltage of 10 kV was applied, and is a subject of improvement to be achieved in near future.

Magnetic Field Stabilization for129Xe EDM Search Experiment

Magnetic field stabilization is a crucial condition parameter for many kinds of ultra-high precision measurements such as a search for an electric dipole moment (EDM). The instability of magnetic field strength often arises from the drift of current flow in a solenoid coil to generate the magnetic field. For our EDM search experiment with maser oscillating diamagnetic 129Xe atoms, we have developed a new stabilized current source based on a feedback system which is devised to correct the amount of current flow measured precisely with high-precision digital multimeter and standard resistor. Using this new current source, we have successfully reduced the drifts of coil current by at least a factor of 100 compared to commercially available current sources.

Development of high-sensitivity NMOR magnetometry for an EDM experiment

Developments are in progress aiming at the search for a permanent Electric Dipole Moment (EDM) in 129Xe atom using a low-frequency nuclear spin maser. In the EDM experiment, drifts in the applied static magnetic field in a long time scale are the dominating source of errors in frequency determination. The stability of the applied field and its monitoring by use of a high sensitivity magnetometer are thus the indispensable part of the EDM experiment. We are developing a magnetometer based on the Nonlinear Magneto-Optical Rotation (NMOR) effect in Rb atom. The sharp response to the magnetic field in this apparatus relies on a long relaxation time of the atomic spin alignment induced by linearly polarized laser light, and thus the suppression of the atomic decoherence should be essential for its sensitivity. Coating the inner walls of the cell with an antirelaxation layer, introducing a buffer gas in the cell and cancelling the transverse magnetic field should be effective in preventing atoms from depolarization. We obtained several NMOR spectra for Rb in cylindrical cells in such attempts. Up to now a sensitivity of ?B=1.5 ? 10?5 G has been attained in the present setup.

Search for an Electric Dipole Moment in 129Xe Atom with Nuclear Spin Oscillator Technique

Development of a nuclear spin oscillator intended for the experimental search for an electric dipole moment in 129Xe atom is reported. The spin oscillation is brought about by polarizing 129Xe nuclear spins by spin exchange with optically polarized Rb atoms, detecting the spin precession through the transmission of a circularly polarized laser light, and applying a feedback field according to the detected spins. Until present, a frequency precision, in a measurement time of T = 45,000 s, of δν = 5.2 nHz has been achieved.