[en] Catalytic activity of an YBaCuO superconducting oxide for the H₂-D₂ exchange reaction has been measured around its Tc with an ultra-high vacuum apparatus. The oxide was crushed with a hammer in vacuum after evacuation of the apparatus (10^-10 Torr). With decreasing the reaction temperature, the first order reaction constant k decreased, but abruptly increased at just below the Tc (Tc, end = 85 K) followed by further decrease in the activity. Since the H₂-D₂ exchange reaction over 3d-transition metal oxides has been though to relate to their 3d_x2-y2 orbitals, the Cu3d_x2-y2 orbital of the YBaCuO oxide must mainly contribute to the superconduction of the oxide

[en] A preliminary result of the solar axion search experiment at the University of Tokyo is presented. We searched for axions which could be produced in the solar core by exploiting the axion helioscope. The helioscope consists of a superconducting magnet with field strength of 4 Tesla over 2.3 meters. From the absence of the axion signal we set a 95% confidence level upper limit on the axion coupling to two photons g_aγγ < 6.0 x 10^-10GeV^-1 for the axion mass m_a < 0.03 eV. This is the first solar axion search experiment whose sensitivity to g_aγγ exceeds the limit inferred from the solar age consideration

[en] We have been developing a stable and accurate high-voltage monitor. Since it uses a ceramic material as the capacitive divider, the monitoring capacitance becomes quite stable against temperature change, or change in setup configuration, or mechanical stress applied to the monitor port through the input lead. In order to verify the safety margin for the maximum operating voltage, we will test on the high-voltage breakdown threshold of the ceramics disk of various materials. This paper reports design details of the high-voltage test equipment, and preparation of the ceramic samples. (author)

[en] Lattice oxygen atoms of terbium oxide have been revealed to play an important role in the oxidation of carbon monoxide by using temperature-programmed desorption (TPD) and ₁₈O-tracer techniques. TPD spectra of oxygen from TbO_x were observed as functions of oxygen absorption temperature, pressure, and time. Two main peaks [α(approx.500₀C) and ß(approx.730₀C)] were observed in the TPD spectra of oxygen from the oxide between 25 and 820₀C, while a small additional peak α' [approx.550₀C] was also observed under certain conditions. The total amount of oxygen desorbed from TbO_1.81 between 25 and 820₀C corresponded to 17% of oxygen atoms in the oxide. When the oxide was allowed an exposure to CO at 320₀C, the α peak intensity was decreased by the formation of CO² from CO. However, when a gas mixture of CO and O² was introduced, the α peak oxygen atoms were not apparently removed by CO although CO² was formed. The most of carbon dioxide formed was composed of C₁₆O², when the terbium oxide was exposed to a mixture of CO and ₁₈O² at 320₀C. On the bases of these findings, it was concluded that the lattice oxygen atoms in TbO_1.81 participated catalytically in the oxidation of carbon monoxide

[en] By shaking a magnetic trap spatially, trapped cold Rb atoms are either heated or further cooled, depending on the shaking frequency. The atom temperature as a function of shaking frequency exhibits a dispersion-shaped resonance, which is caused by frequency selective energy absorption due to the anharmonicity of the trap potential. Selective heating of high-energy atoms enhances their loss, which can result in cooling rather than heating of a trapped atomic cloud

No abstract available

[en] We have succeeded in simultaneously trapping a fermion and boson isotope pair of ytterbium (Yb) in a far off-resonant trap (FORT). We have found evidence of elastic cross collisions between fermions and bosons, and performed a successful sympathetic cooling of the fermions. We could also enhance the loading of the fermions ¹⁷¹Yb in the crossing region in a crossed FORT via cross collisions between the fermions ¹⁷¹Yb and the bosons ¹⁷⁴Yb

[en] We could recently achieve the Bose Einstein condensation (BEC) of Yb atoms. Yb differs from most of the elements that have previously been condensed, because it is a two-electron atom with the singlet S ground state. Furthermore the Bosonic isotopes of Yb, like 174Yb which we succeeded to condensate, has no nuclear spin, so that the ground state is completely spin-less state and hence insensitive to magnetic fields. Thus a new type of atom could join the group of atoms for BEC studies. We would like to report how we could achieve the BEC of Yb atoms

[en] We report the photoassociation spectroscopy of laser-cooled ytterbium atoms in an optical trap. We observed more than 90 photoassociation resonances of vibrational levels in the Σ_u⁺¹ state, including 80 consecutive series, up to 490 GHz detuning with respect to the atomic resonance. From the resonance frequencies we derived the atomic radiative lifetime of the (6s6p) P₁¹ state to be 5.464±0.005 ns, which is about 2 orders of magnitude improvement over previous results. We also observed line broadening of resonances, which is ascribed to the predissociation to the triplet states, and estimated the transition probability to be 0.2. Furthermore, we observed the decrease of the photoassociation signal intensity, from which the scattering length is estimated to be equal to or less than 3 nm

No abstract available