325 research outputs found

    Observation of Three-dimensional Long-range Order in Smaller Ion Coulomb Crystals in an rf Trap

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    Three-dimensional long-range ordered structures in smaller and near-spherically symmetric Coulomb crystals of ^{40}Ca^+ ions confined in a linear rf Paul trap have been observed when the number of ions exceeds ~1000 ions. This result is unexpected from ground state molecular dynamics (MD) simulations, but found to be in agreement with MD simulations of metastable ion configurations. Previously, three-dimensional long-range ordered structures have only been reported in Penning traps in systems of ~50,000 ions or more.Comment: 5 pages; 4 figures; to appear in Phys. Rev. Lett.; changed content

    Deep rest-frame far-UV spectroscopy of the giant Lyman-alpha emitter 'Himiko'

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    We present deep 10h VLT/XSHOOTER spectroscopy for an extraordinarily luminous and extended Lya emitter at z=6.595 referred to as Himiko and first discussed by Ouchi et al. (2009), with the purpose of constraining the mechanisms powering its strong emission. Complementary to the spectrum, we discuss NIR imaging data from the CANDELS survey. We find neither for HeII nor any metal line a significant excess, with 3 sigma upper limits of 6.8, 3.1, and 5.8x10^{-18} erg/s/cm^2 for CIV λ\lambda1549, HeII λ\lambda1640, CIII] λ\lambda1909, respectively, assuming apertures with 200 km/s widths and offset by -250 km/s w.r.t to the peak Lya redshift. These limits provide strong evidence that an AGN is not a major contribution to Himiko's Lya flux. Strong conclusions about the presence of PopIII star-formation or gravitational cooling radiation are not possible based on the obtained HeII upper limit. Our Lya spectrum confirms both spatial extent and flux (8.8+/-0.5x10^{-17} erg/s/cm^2) of previous measurements. In addition, we can unambiguously exclude any remaining chance of it being a lower redshift interloper by significantly detecting a continuum redwards of Lya, while being undetected bluewards

    An ion ring in a linear multipole trap for optical frequency metrology

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    A ring crystal of ions trapped in a linear multipole trap is studied as a basis for an optical frequency standard. The equilibrium conditions and cooling possibilities are discussed through an analytical model and molecular dynamics simulations. A configuration which reduces the frequency sensitivity to the fluctuations of the number of trapped ions is proposed. The systematic shifts for the electric quadrupole transition of calcium ions are evaluated for this ring configuration. This study shows that a ring of 10 or 20 ions allows to reach a short term stability better than for a single ion without introducing limiting long term fluctuations

    Sensing RF fields with a distant stand-alone Rydberg-atomic receiver

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    We combine a rubidium vapour cell with a corner-cube prism reflector to form a passive RF receiver, allowing the detection of microwave signals at a location distant from the active components required for atomic sensing. This compact receiver has no electrical components and is optically linked to the active base station by a pair of free-space laser beams that establish an electromagnetically induced transparency scenario in the atomic vapour. Microwave signals at the receiver location are imprinted onto an optical signal which is detected at the base station. Our stand-alone receiver architecture adds important flexibility to Rydberg-atom based sensing technologies, which are currently subject to significant attention. We demonstrate a ~20 m link with no particular effort and foresee significant future prospects of achieving a much larger separation between receiver and base station

    Risk analysis of a distillation unit

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    A risk analysis of a batch distillation unit is de-scribed. The analysis has been carried out at several stages during plant design, construction, and operation. The costs, quality, and benefits is using the methods are described

    The scaling relations of early--type galaxies in clusters I. Surface photometry in seven nearby clusters

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    This is the first paper of a series investigating the scaling relations of early-type galaxies in clusters. Here we illustrate the multi-band imagery and the image reduction and calibration procedures relative to the whole sample of 22 clusters at 0.05 < z < 0.25. We also present the detailed surface photometry of 312 early-type galaxies in 7 clusters in the first redshift bin, z~0.025-0.075. We give for each galaxy the complete set of luminosity and geometrical profiles, and and a number of global, photometric and morphological parameters. They have been evaluated taking into account the effects of seeing. Internal consistency checks and comparisons with data in the literature confirm the quality of our analysis. These data, together with the spectroscopic ones presented in the second paper of the series, will provide the local calibration of the scaling relations.Comment: 36 pages, 13 figures, 7 tables, accepted for publication in A&

    Non-Destructive Probing of Rabi Oscillations on the Cesium Clock Transition near the Standard Quantum Limit

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    We report on non-destructive observation of Rabi oscillations on the Cs clock transition. The internal atomic state evolution of a dipole-trapped ensemble of cold atoms is inferred from the phase shift of a probe laser beam as measured using a Mach-Zehnder interferometer. We describe a single color as well as a two-color probing scheme. Using the latter, measurements of the collective pseudo-spin projection of atoms in a superposition of the clock states are performed and the observed spin fluctuations are shown to be close to the standard quantum limit.Comment: 4 pages, 4 figures, accepted for publication in Physical Review Letter

    The scaling relation of early-type galaxies in clusters. II: Spectroscopic data for galaxies in eight nearby clusters

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    AIMS: We present in this work low and intermediate resolution spectroscopic data collected for 152 early type galaxies in 8 nearby clusters with z \leq 0.10. METHODS: We use low resolution data to produce the redshift and the K-correction for every individual galaxy, as well as to give their overall spectral energy distribution, and some spectral indicators, including the 4000\AA break, the Mg2_2 strength, and the NaD equivalent width.We have also obtained higher resolution data for early type galaxies in three of the clusters, to determine their central velocity dispersion. RESULTS: The effect of the resolution on the measured parameters is discussed. CONCLUSIONS: New accurate systemic redshift and velocity dispersion is presented for four of the surveyed clusters, A98, A3125, A3330, and DC2103-39. We have found that the K-correction values for E/S0 bright galaxies in a given nearby clusters are very similar. We also find that the distribution of the line indicators significantly differ from cluster to cluster.Comment: 16 pages, 9 figures, Accepted in A&
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