NSCL Directory Profile

Kei Minamisono
Research Staff Physicist and Adjunct Professor of Physics
Experimental Nuclear Physics
PhD, Physics, Osaka University, 1999
Joined NSCL in October 2004
Phone(517) 908-7145
Fax(517) 353-5967
Photograph of Kei Minamisono

Selected Publications:
Collinear laser spectroscopy on the ground state and an excited state in neutral 55Mn, A. K. Klose, K. Minamisono, and P. F. Mantica, Phys. Rev. A, in press.

Commissioning of the Collinear Laser Spectroscopy System in the BECOLA Facility at NSCL, K. Minamisono et al., Nucl. Instrum. Methods A 709, 85 (2013).

Low Energy Test of SCC in beta Decays of Spin Aligned 20F and 20Na, K. Minamisono et al., Phys. Rev. C 84, 055501 (2011).

Doubly-Magic Nature of 56Ni: Measurement of the Ground State Nuclear Magnetic Dipole Moment of 55Ni, J. S. Berryman et al., Phys. Rev. C 79, 064305 (2009).

Quadrupole moment of Neutron-Deficient 20, 21Na, K. Minamisono et al., Phys. Lett. B 672, 120 (2009).
One of my current research interests as an experimentalist is to determine some of the fundamental ground-state properties, the magnetism and shapes, of radioactive isotopes away from the beta stability line, and towards the nucleon drip lines in the nuclear chart. The nuclear magnetic-dipole moment arises from orbital angular momentum and intrinsic spin and sensitive to the valence-nucleon configuration in a nucleus. The nuclear-quadrupole moment and charge radius represent the charge distribution inside the nucleus and sensitive to the shape and deformation.

Laser assisted techniques are used in the experiment; the collinear laser spectroscopy with bunched beams and beta-ray detecting Nuclear Magnetic Resonance technique. Laser light and ion beam are co-propagated through the interaction region and resulting resonant fluorescence and/or nuclear polarization is detected. High precision/resolution laser systems and a detection system with great sensitivity are required to resolve hyperfine structure of low production-rate radioactive isotopes.

I am also interested in testing the time reversal (T) invariance in the light quark system. The T invariance is essential as a complementary symmetry to the CP symmetry, which is thought to have played a crucial role in producing the excess of matter over antimatter early in the history of the universe, which cannot be explained in the Standard Model. A specific nucleus that enhances such symmetry breaking effect is carefully selected to perform beta-decay correlation measurements with spin polarized/aligned nuclei.

Such studies can be realized at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL. Both laser-hyperfine-structure measurements and atomic/nuclear spin manipulation to produce polarization will be performed for rare isotopes at low-production rates. BECOLA has been online since the summer 2013 and will explore, as an initial experimental project, nuclear structure of radioactive isotopes of the first row transition elements, which are only available at NSCL.

Hyperfine structures and isotope shifts of stable and radioactive potassium isotopes are shown for D1 and D2 transitions. Relative shift of centroids of the resonance structures from that of 39K is the isotope shift, from which charge radius can be extracted. The hyperfine structure (splittings) of each spectrum corresponds to the isotope’s nuclear moments i.e. magnetic and quadrupole moments.