9,292 research outputs found

    Velocity-selective sublevel resonance of atoms with an array of current-carrying wires

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    Resonance transitions between the Zeeman sublevels of optically-polarized Rb atoms traveling through a spatially periodic magnetic field are investigated in a radio-frequency (rf) range of sub-MHz. The atomic motion induces the resonance when the Zeeman splitting is equal to the frequency at which the moving atoms feel the magnetic field oscillating. Additional temporal oscillation of the spatially periodic field splits a motion-induced resonance peak into two by an amount of this oscillation frequency. At higher oscillation frequencies, it is more suitable to consider that the resonance is mainly driven by the temporal field oscillation, with its velocity-dependence or Doppler shift caused by the atomic motion through the periodic field. A theoretical description of motion-induced resonance is also given, with emphasis on the translational energy change associated with the internal transition.Comment: 7 pages, 3 figures, final versio

    Ground-state electric quadrupole moment of 31Al

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    Ground-state electric quadrupole moment of 31Al (I =5/2+, T_1/2 = 644(25) ms) has been measured by means of the beta-NMR spectroscopy using a spin-polarized 31Al beam produced in the projectile fragmentation reaction. The obtained Q moment, |Q_exp(31Al)| = 112(32)emb, are in agreement with conventional shell model calculations within the sd valence space. Previous result on the magnetic moment also supports the validity of the sd model in this isotope, and thus it is concluded that 31Al is located outside of the island of inversion.Comment: 5 page

    Searching for ΜΌ→Μτ\nu_\mu \to \nu_\tau Oscillations with Extragalactic Neutrinos

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    We propose a novel approach for studying ΜΌ→Μτ\nu_\mu \to \nu_\tau oscillations with extragalactic neutrinos. Active Galactic Nuclei and Gamma Ray Bursts are believed to be sources of ultrahigh energy muon neutrinos. With distances of 100 Mpc or more, they provide an unusually long baseline for possible detection of ΜΌ→Μτ\nu_\mu \to \nu_\tau with mixing parameters Δm2\Delta m^2 down to 10−1710^{-17}eV2^2, many orders of magnitude below the current accelerator experiments. By solving the coupled transport equations, we show that high-energy Μτ\nu_\tau's, as they propagate through the earth, cascade down in energy, producing the enhancement of the incoming Μτ\nu_\tau flux in the low energy region, in contrast to the high-energy ΜΌ\nu_\mu's, which get absorbed. For an AGN quasar model we find the Μτ\nu_\tau flux to be a factor of 2 to 2.5 larger than the incoming flux in the energy range between 10210^2 GeV and 10410^4 GeV, while for a GRB fireball model, the enhancement is 10%-27% in the same energy range and for zero nadir angle. This enhancement decreases with larger nadir angle, thus providing a novel way to search for Μτ\nu_\tau appearance by measuring the angular dependence of the muons. To illustrate how the cascade effect and the Μτ\nu_\tau final flux depend on the steepness of the incoming Μτ\nu_\tau, we show the energy and angular distributions for several generic cases of the incoming tau neutrino flux, FÎœ0∌E−nF_\nu^0 \sim E^{-n} for n=1,2 and 3.6. We show that for the incoming flux that is not too steep, the signal for the appearance of high-energy Μτ\nu_\tau is the enhanced production of lower energy ÎŒ\mu and their distinctive angular dependence, due to the contribution from the τ\tau decay into ÎŒ\mu just below the detector.Comment: 11 pages, including 4 color figure

    Classification of Light-Induced Desorption of Alkali Atoms in Glass Cells Used in Atomic Physics Experiments

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    We attempt to provide physical interpretations of light-induced desorption phenomena that have recently been observed for alkali atoms on glass surfaces of alkali vapor cells used in atomic physics experiments. We find that the observed desorption phenomena are closely related to recent studies in surface science, and can probably be understood in the context of these results. If classified in terms of the photon-energy dependence, the coverage and the bonding state of the alkali adsorbates, the phenomena fall into two categories: It appears very likely that the neutralization of isolated ionic adsorbates by photo-excited electron transfer from the substrate is the origin of the desorption induced by ultraviolet light in ultrahigh vacuum cells. The desorption observed in low temperature cells, on the other hand, which is resonantly dependent on photon energy in the visible light range, is quite similar to light-induced desorption stimulated by localized electronic excitation on metallic aggregates. More detailed studies of light-induced desorption events from surfaces well characterized with respect to alkali coverage-dependent ionicity and aggregate morphology appear highly desirable for the development of more efficient alkali atom sources suitable to improve a variety of atomic physics experiments.Comment: 6 pages, 1 figure; minor corrections made, published in e-Journal of Surface Science and Nanotechnology at http://www.jstage.jst.go.jp/article/ejssnt/4/0/4_63/_articl

    The HST Cosmos Project: Contribution from the Subaru Telescope

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    The Cosmic Evolution Survey (COSMOS) is a Hubble Space Telescope (HST) treasury project.The COSMOS aims to perform a 2 square degree imaging survey of an equatorial field in II(F814W) band, using the Advanced Camera for Surveys (ACS). Such a wide field survey, combined with ground-based photometric and spectroscopic data, is essential to understand the interplay between large scale structure, evolution and formation of galaxies and dark matter. In 2004, we have obtained high-quality, broad band images of the COSMOS field (B,V,râ€Č,iâ€Č,B, V, r^\prime, i^\prime, and zâ€Č z^\prime) using Suprime-Cam on the Subaru Telescope, and we have started our new optical multi-band program, COSMOS-21 in 2005. Here, we present a brief summary of the current status of the COSMOS project together with contributions from the Subaru Telescope. Our future Subaru program, COSMOS-21, is also discussed briefly.Comment: 4 pages, 3 figures, to appear in the Proceedings of the 6th East Asian Meeting on Astronomy, JKAS, 39, in pres
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