S. Matsuki

Manipulating ionization path in a Stark map: Stringent schemes for the selective field ionization in highly excited Rb Rydberg

We have developed a quite stringent method in selectivity to ionize the low angular-momentum (l) states which lie below and above the adjacent manifold in highly excited Rb Rydberg atoms. The method fully exploits the pulsed field-ionization characteristics of the manifold states in high slew-rate regime: Specifically the low l state below (above) the adjacent manifold is firstly transferred to the lowest (highest) state in the manifold via the adiabatic transition at the first avoided crossing in low slew-rate regime, and then the atoms are driven to a high electric field for ionization in high slew-rate regime. These extreme states of the manifold are ionized at quite different fields due to the tunneling process, resulting in thus the stringent selectivity. Two manipulation schemes to realize this method actually are demonstrated here experimentally.

The 2+2 and 4+1 states of the even isotopes 78–86Kr excited in the inelastic scattering of 51.9 MeV protons

Abstract The 2 + 2 and 4 + 1 states of the even isotopes 78–86 Kr have been studied by the inelastic scattering of protons. The B (E2;0 + g → 2 + 2 ) values of these isotopes are roughly equal, where as the B (E4; + g → 4 + 1 ) values decrease to a minimum at 82 Kr and then increase with neutron number. Comparison of the experimental results with current theoretical models implies an abrupt change of structure between 78–82 Kr and 84–86 Kr.

CARRACK II — a new large-scale experiment to search for axions with Rydberg-atom cavity detector

Abstract Based on the performance of the Rydberg-atom cavity detector now running, a new large-scale apparatus to search for axions over a wide range of mass is under construction. The system detail and the aimed search area are presented.

Systematic study of the (d, p) reaction with 56 MeV polarized deuterons

Abstract Differential cross sections and vector analyzing powers were measured for the (d, p) reaction with 56 MeV polarized deuterons. The investigation covered the transitions to the single-particle states of the 1p. 2s, 1d. 2p, 1f, 3s, 2d and 1g shells. The analyzing powers showed a j -dependence which depended on the number of nodes in the radial wave function of the transferred neutron. DWBA and adiabatic model calculations were carried out. The DWBA calculations reproduced the experimental cross sections and analyzing powers for the stripping to the j > states. The adiabatic model did not necessarily improve the fits to the data for these transitions. As for the j transitions, on the other hand, the DWBA calculations could not reproduce the experimental angular distributions, while the adiabatic model calculations improved the agreement with the experimental data.

Splitting of low-lying octupole vibrational strength in 76,78,80,82Kr

Abstract Two low-lying octupole states of 78,80,82Kr, which were previously observed in inelastic proton scattering to share the low-lying octupole vibrational strength, were found to be strongly excited in the (p,t) reaction. Characteristics of these states and a comparison with the IBM model strongly suggest that the splittings in the lighter isotopes 76,78,80,82Kr are due to a coupling of the octupole vibration to the quadrupole degree of freedom.

Study of 112Cd via high-resolution (d, d′) and (p, p′) reactions and IBA model calculations

Abstract High-resolution inelastic-scattering measurements on 112 Cd with polarized deuterons (20 MeV) and polarized protons (16 and 65 MeV) provide complete spectroscopic information. Transition moments are obtained from the angular distributions of the cross section and analyzing power in a coupled-channel reaction analysis. The results are compared with interacting boson model predictions aiming to describe intruder states, quadrupole-hexadecapole and quadrupole-octupole excitations.

The Rydberg-Atom-Cavity Axion Search

We report on the present progress in development of the dark matter axion search experiment with Rydberg-atom-cavity detectors in Kyoto, CARRACK I and CARRACK II. The axion search has been performed with CARRACK I in the 8% mass range around 10µeV, and CARRACK II is now ready for the search in the wide range 2µeV – 50µeV. We have also developed quantum theoretical calculations on the axion-photon-atom system in the resonant cavity in order to estimate precisely the detection sensitivity for the axion signal. Some essential features on the axion-photon-atom interaction are clarified, which provide the optimum experimental setup for the axion search.

Direct detection of galactic axions with Rydberg atoms in an inhibited cavity regime

Abstract A new scheme to detect galactic axions directly with Rydberg atoms is proposed and discussed. Rydberg atoms are excited from the lower to the upper fine-structure states by absorbing the axions in an inhibited (non-resonant) cavity regime. The weak transition rate in axion absorption could be enormously enhanced due to the huge occupation number of the axions if the axions constitute our galactic halo, while the transition rate in photon absorption could be strongly suppressed in a cooled, inhibited cavity regime. Thus it would be possible to get a good signal-to-noise ratio for axion hunting.

Level structure of 80,82Sr via the 78,80Kr(α, 2nγ) reactions

Abstract The level structure of 80,82 Sr was studied with in-beam γ-ray spectroscopy via the 78,80 Kr(α, 2nγ) 80,82 Sr reactions at E α = 28.7 MeV. From the angular distributions and γ-γ coincidence measurements, the ground-state band up to (10 + ) and some other states were observed in both nuclei. The deduced levels are compared with current theoretical models. The observed level structure in neutron deficient Sr isotopes indicates a transition from spherical to deformed as neutron number decreases from 50 to 40.

A precision measurement of the hyperfine structure of87Sr

The ground state hyperfine splitting of87Sr+ was measured with a precision of 1×10−8. The experiments were performed with an RF ion trap connected to an ISOL (isotope separator on-line), where all the possible transitions between Zeeman sublevels were observed by a laser-microwave double resonance method. The magnetic dipole hyperfine constant was determined to beA=−1 000 473.673 (11) kHz.