XMM-Newton Observation of the Cluster of Galaxies Abell 1650

We present the nonuniform distribution of temperature and abundance in the angular extent of 10'(1.4 Mpc) in A1650 observed by XMM-Newton. Spectral analysis was carried out in 19 systematically-subdivided regions, and in 15 specified regions referred to the hardness ratio (HR) map. The value of HR, defined as the ratio of counts in the 1.6-10 keV band to those in the 0.8-1.6 keV, is an indicator to investigate the spatial variation of spectral features. The temperature and abundance were obtained to be 4-6 keV and 0.2-0.5 solar value with average values of 5.62+0.05-0.07 keV and 0.36+0.02-0.01 solar value within a radius of 5', respectively. The redshift was derived to be 8.01+0.02-0.02x10^-2 against an optical value of 8.45x10^-2. It turned out that cool regions with a temperature of around 4 keV and a scalelength of a few 100 kpc are patchily distributed in the outer envelope. This temperature structure could be explained by the infalling of groups of galaxies into the cluster main body. More than 30 point sources were found around A1650 in the FOV of 30'. The spectrum of the Galactic diffuse emission was obtained in the outskirts of A1650.Comment: 9 pages, 12 figures; Published on PAS

All-Optical Formation of Quantum Degenerate Mixtures

We report the realization of quantum degenerate mixed gases of ytterbium (Yb) isotopes using all-optical methods. We have succeeded in cooling attractively interacting 176Yb atoms via sympathetic cooling down to below the Bose-Einstein transition temperature, coexisting with a stable condensate of 174Yb atoms with a repulsive interaction. We have observed a rapid atom loss in 176Yb atoms after cooling down below the transition temperature, which indicates the collapse of a 176Yb condensate. The sympathetic cooling technique has been applied to cool a 173Yb-174Yb Fermi-Bose mixture to the quantum degenerate regime.Comment: 4 pages, 3 figure

Bose-Einstein condensate in gases of rare atomic species

We report on the successful extension of production of Bose-Einstein Condensate (BEC) to rare species. Despite its low natural abundance of 0.13%, $^{168}$Yb is directly evaporatively cooled down to BEC. Our successful demonstration encourages attempts to obtain quantum gases of radioactive atoms, which extends the possibility of quantum many-body physics and precision measurement. Moreover, a stable binary mixture of $^{168}$Yb BEC and $^{174}$Yb BEC is successfully formed.Comment: 5 pages, 3 figures. Accepted for Phys. Rev.

Bose-Einstein Condensation of an Ytterbium Isotope

We report the observation of a Bose Einstein condensate in a bosonic isotope of ytterbium (170Yb). More than 10^6 atoms are trapped in a crossed optical dipole trap and cooled by evaporation. Condensates of approximately 10^4 atoms have been obtained. From an expansion of the condensate, we have extracted the scattering length a=3.6(9) nm.Comment: 4 pages, 3 figure

Resonant Control of Interaction Between Different Electronic States

We observe a magnetic Feshbach resonance in a collision between the ground and metastable states of two-electron atoms of ytterbium (Yb). We measure the on-site interaction of doubly-occupied sites of an atomic Mott insulator state in a three-dimensional optical lattice as a collisional frequency shift in a high-resolution laser spectroscopy. The observed spectra are well fitted by a simple theoretical formula, in which two particles with an s-wave contact interaction are confined in a harmonic trap. This analysis reveals a wide variation of the interaction with a resonance behavior around a magnetic field of about 1.1 Gauss for the energetically lowest magnetic sublevel of ${}^{170}$Yb, as well as around 360 mG for the energetically highest magnetic sublevel of ${}^{174}$Yb. The observed Feshbach resonance can only be induced by an anisotropic inter-atomic interaction. This novel scheme will open the door to a variety of study using two-electron atoms with tunable interaction.Comment: 5 pages, 5 figure