M. Wada

Cyclotron ion guide for energetic radioactive nuclear ions

A new ion guide, with an additional function having an infinite gas thickness by using a strong magnetic field, is proposed, which enables us to stop energetic radioactive nuclear ions in He gas. The stopped singly charged ions, guided in a dc field with a focusing force generated by an rf field in the gas, are extracted with a SPIG (sextupole rf ion guide) of a focusing device for a spectroscopic study of radioactive nuclei.

Laser-Microwave Double-Resonance Spectroscopy of Laser-Cooled ^9Be^+ Ions in a Weak Magnetic Field for Studying Unstable Be Isotopes

Laser-microwave double-resonance spectroscopy of laser-cooled 9 Be + ions in a linear Paul trap has been performed aiming at the development of both highly sensitive and precise methods to be applied to the unstable isotopes. By the alternative irradiation of laser and microwave radiationxa0(pulsed-wave method), high accuracy of 4×10 -7 was obtained in the measurement of the ground-state magnetic-dipole hyperfine constant ( A ) of 9 Be + ion in a weak magnetic field. By the continuous-wave method, high sensitive detection of the microwave resonance was demonstrated. These methods can be complementarily applied to the measurements of unknown hyperfine constants of the unstable isotopes for studying the hyperfine anomaly.

Laser-microwave spectroscopy of the hyperfine structure of 9Be for the investigation of unstable Be isotopes

Abstract For an investigation concerning the nuclear magnetic moments and their distributions in the nuclei of 7,11Be, an experimental project using laser-microwave double resonance spectroscopy for trapped ions is under progress at INS. Laser cooled ion crystals consisting of a few 9Be+ ions were observed and the ground state hyperfine splitting of 9Be+ was measured with a precision of 10−5. Experiments on the unstable isotope 7Be have been started.

Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-of-flight mass spectrograph

Abstract High-precision mass measurements of Cu 63 , Zn 64 − 66 , Ga 65 , Ge 65 − 67 , As 67 , Br 78 , 81 , Rb 80 , and Sr 79 were performed utilizing a multireflection time-of-flight mass spectrograph combined with the gas-filled recoil ion separator GARIS-II. In the case of Ga 65 , a mass uncertainty of 2.1xa0keV, corresponding to a relative precision of δm/mxa0=xa03.5xa0×xa010−8, was obtained and the mass value is in excellent agreement with the 2016 Atomic Mass Evaluation. For Ge 67 and Br 81 , where masses were previously deduced through indirect measurements, discrepancies with literature values were found. The feasibility of using this device for mass measurements of more neutron-deficient nuclei, which have significant impact on the rp-process pathway, is discussed.

A Laser-Microwave Double Resonance for Unstable Nuclear Ions

We report the results of laser-microwave double resonance spectroscopy of laser cooled 9Be+ ions trapped in a linear rf trap. The microwave transition frequency between the sublevels of the 9Be+ ground state hyperfine structure in a weak magnetic field was measured with a precision of 5 × 10−6. This experiment has been carried out as a first step of our project to study the hyperfine anomaly of unstable nuclear ions at INS.

Improving wide-band mass measurements in a multi-reflection time-of-flight mass spectrograph by usage of a concomitant measurement scheme

Abstract We introduce a new concomitant referencing mode for operating a multi-reflection time-of-flight mass spectrograph (MRTOF-MS), wherein the reference and analyte ions are interleaved on a cycle by cycle basis. Using this mode, we demonstrate an improved technique for performing wide bandwidth mass measurements via MRTOF-MS. This new technique offers a simplified analysis and high accuracy.

Status of the laser-microwave spectroscopy experiment for the hyperfine structure of 7Be

In order to investigate the nuclear magnetic moments and the magnetization distributions in the unstable nuclei of 7,11Be, laser-microwave spectroscopy experiments using an ion-trap are under progress at IPNS, KEK-Tanashi. Status of the experiment for the first unstable isotope 7Be is reported.