Search results for "SCOPE"
showing 10 items of 2420 documents
Spin scattering and spin-polarized hybrid interface states at a metal-organic interface
2011
Spin scattering at the interface formed between metallic Fe and Cu-phthalocyanine molecules is investigated by spin-polarized scanning tunneling spectroscopy and spin-resolved photoemission. The results are interpreted using first-principles electronic structure theory. The combination of experimental and theoretical techniques allows us to shed light on the role of hybrid interface states for the spin scattering. We show that Cu-phthalocyanine acts, via hybrid interface states, as a local spin filter up to room temperature both below and above the Fermi energy, ${E}_{\mathrm{F}}$. At the same time, the molecule behaves as a featureless scattering barrier in a region of about 1 eV around ${…
Spatial distribution and statistical properties of small-scale convective vortex-like motions in a quiet-Sun region
2011
High-resolution observations of a quiet Sun internetwork region taken with the Solar 1-m Swedish Telescope in La Palma are analyzed. We determine the location of small-scale vortex motions in the solar photospheric region by computing the horizontal proper motions of small-scale structures on time series of images. These plasma convectively-driven swirl motions are associated to: (1) downdrafts (that have been commonly explained as corresponding to sites where the plasma is cooled down and hence returned to the interior below the visible photospheric level), and (2) horizontal velocity vectors converging into a central point. The sink cores are proved to be the final destination of passive …
ESTREMO/WFXRT: Extreme phySics in the TRansient and Evolving COsmos
2006
We present a mission designed to address two main themes of the ESA Cosmic Vision Programme: the Evolution of the Universe and its Violent phenomena. ESTREMO/WFXRT is based on innovative instrumental and observational approaches, out of the mainstream of observatories of progressively increasing area, i.e.: Observing with fast reaction transient sources, like GRB, at their brightest levels, thus allowing high resolution spectroscopy. Observing and surveying through a X-ray telescope with a wide field of view and with high sensitivity extended sources, like cluster and Warm Hot Intragalactic Medium (WHIM). ESTREMO/WFXRT will rely on two cosmological probes: GRB and large scale X-ray structur…
A Study of Gravitational Lens Chromaticity using Ground-based Narrow Band Photometry
2011
We present observations of wavelength-dependent flux ratios for four gravitational lens systems (SDSS~J1650+4251, HE~0435$-$1223, FBQ 0951+2635, and Q~0142$-$100) obtained with the Nordic Optical Telescope. The use of narrowband photometry, as well as the excellent seeing conditions during the observations, allows us to study their chromatic behavior. For SDSS~J1650+4251, we determine the extinction curve of the dust in the $z_L=0.58$ lens galaxy and find that the 2175 \AA \ feature is absent. In the case of HE~0435$-$1223, we clearly detect chromatic microlensing. This allows us to estimate the wavelength-dependent size of the accretion disk. We find an R-band disk size of $r^{R}_s=13\pm5$…
New limits on Early Dark Energy from the South Pole Telescope
2011
We present new limits on early dark energy (EDE) from the cosmic microwave background (CMB) using data from the WMAP satellite on large angular scales and South Pole Telescope (SPT) on small angular scales. We find a strong upper limit on the EDE density of Omega_e < 0.018 at 95% confidence, a factor of three improvement over WMAP data alone. We show that adding lower-redshift probes of the expansion rate to the CMB data improves constraints on the dark energy equation of state, but not the EDE density. We also explain how the small-scale CMB temperature anisotropy constrains EDE.
Dark matter scattering on electrons: Accurate calculations of atomic excitations and implications for the DAMA signal
2016
We revisit the WIMP-type dark matter scattering on electrons that results in atomic ionization and can manifest itself in a variety of existing direct-detection experiments. Unlike the WIMP-nucleon scattering, where current experiments probe typical interaction strengths much smaller than the Fermi constant, the scattering on electrons requires a much stronger interaction to be detectable, which in turn requires new light force carriers. We account for such new forces explicitly, by introducing a mediator particle with scalar or vector couplings to dark matter and to electrons. We then perform state-of-the-art numerical calculations of atomic ionization relevant to the existing experiments.…
LONG-TERM MONITORING, TIME DELAY, AND MICROLENSING IN THE GRAVITATIONAL LENS SYSTEM Q0142-100
2013
We present twelve years of monitoring of the gravitational lens Q0142-100 from the Teide Observatory. The data, taken from 1999 to 2010, comprise 105 observing nights with the IAC80 telescope. The application of the delta2-method to the dataset leads to a value of the time delay between both components of the system of 72+/-22 days (68 per cent confidence level), consistent within the uncertainties with the latest previous results. With this value in mind a possible microlensing event is detected in Q0142-100.
A measurement of the tau lifetime
1993
The tau lepton lifetime is measured using four different methods with the DELPHI detector. Three measurements using one prong decays are combined, accounting for correlations, resulting in tau(tau) = 298 +/- 7 (stat.) +/- 4 (syst.) fs while the decay length distribution of three prong decays gives tau(tau) = 298 +/- 13 (stat.) +/- 5 (syst.) fs. The combined result is tau(tau) = 298 +/- 7 fs. The ratio of the Fermi coupling constant from tau decay relative to that from muon decay is found to be 0.985 +/- 0.013, compatible with lepton universality.
CONSTRUCTION OF METASTABLE STATES IN QUANTUM ELECTRODYNAMICS
2004
In this paper, we construct metastable states of atoms interacting with the quantized radiation field. These states emerge from the excited bound states of the non-interacting system. We prove that these states obey an exponential time-decay law. In detail, we show that their decay is given by an exponential function in time, predicted by Fermi's Golden Rule, plus a small remainder term. The latter is proportional to the (4+β)th power of the coupling constant and decays algebraically in time. As a result, though it is small, it dominates the decay for large times. A central point of the paper is that our remainder term is significantly smaller than the one previously obtained in [1] and as…
Calibration and Simulation of the GRB trigger detector of the Ultra Fast Flash Observatory
2013
The UFFO (Ultra-Fast Flash Observatory) is a GRB detector on board the Lomonosov satellite, to be launched in 2013. The GRB trigger is provided by an X-ray detector, called UBAT (UFFO Burst Alarm & Trigger Telescope), which detects X-rays from the GRB and then triggers to determine the direction of the GRB and then alerts the Slewing Mirror Telescope (SMT) to turn in the direction of the GRB and record the optical photon fluxes. This report details the calibration of the two components: the MAPMTs and the YSO crystals and simulations of the UBAT. The results shows that this design can observe a GRB within a field of view of ±35° and can trigger in a time scale as short as 0.2 – 1.0 s af…