3,913 research outputs found

    The KATRIN Experiment

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    The KArlsruhe TRitium Neutrino mass experiment, KATRIN, aims to search for the mass of the electron neutrino with a sensitivity of 0.2 eV/c^2 (90% C.L.) and a detection limit of 0.35 eV/c^2 (5 sigma). Both a positive or a negative result will have far reaching implications for cosmology and the standard model of particle physics and will give new input for astroparticle physics and cosmology. The major components of KATRIN are being set up at the Karlsruhe Institut of Technology in Karlsruhe, Germany, and test measurements of the individual components have started. Data taking with tritium is scheduled to start in 2012.Comment: 3 pages, 1 figure, proceedings of the TAUP 2009 International Conference on Topics in Astroparticle and Underground Physics, to be published in Journal of Physics, Conference Serie

    Status of Nucleon Resonances with Masses M<MN+MπM<M_N+M_{\pi}

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    We discuss different interpretations of peaks observed a few years ago by Tatischeff et al. in missing mass spectra of the reaction pp>pi+pXpp->pi^+pX, which were declared as new exited nucleon states with small masses. A study of the possible production of such states in the process γp>pi+N>pi++γγn\gamma p->pi^+N^*->pi^+ +\gamma\gamma n by analyzing the invariant mass spectrum of γγn\gamma\gamma n is proposed. It is shown that the data, obtained recently at MAMI-B, can allow to analyze this process and to get information about an existence of exited nucleon states with small masses.Comment: 4 pages, 2 figures, LaTeX with ws-p8-50x6-00.cls. Talk presented at the NSTAR2001 Workshop, Mainz, Germany, March 7-10, 200

    Dark states of single NV centers in diamond unraveled by single shot NMR

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    The nitrogen-vacancy (NV) center in diamond is supposed to be a building block for quantum computing and nanometer scale metrology at ambient conditions. Therefore, precise knowledge of its quantum states is crucial. Here, we experimentally show that under usual operating conditions the NV exists in an equilibrium of two charge states (70% in the expected negative (NV-) and 30% in the neutral one (NV0)). Projective quantum non-demolition measurement of the nitrogen nuclear spin enables the detection even of the additional, optically inactive state. The nuclear spin can be coherently driven also in NV0 (T1 ~ 90 ms and T2 ~ 6 micro-s).Comment: 4 pages, 3 figure

    Variable accretion as a mechanism for brightness variations in T Tau S

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    (Note: this is a shortened version of the original A&A-style structured abstract). The physical nature of the strong photometric variability of T Tau Sa, the more massive member of the Southern "infrared companion" to T Tau, has long been debated. Intrinsic luminosity variations due to variable accretion were originally proposed but later challenged in favor of apparent fluctuations due to time-variable foreground extinction. In this paper we use the timescale of the variability as a diagnostic for the underlying physical mechanism. Because the IR emission emerging from Sa is dominantly thermal emission from circumstellar dust at <=1500K, we can derive a minimum size of the region responsible for the time-variable emission. In the context of the variable foreground extinction scenario, this region must be (un-) covered within the variability timescale, which implies a minimum velocity for the obscuring foreground material. If this velocity supercedes the local Kepler velocity we can reject foreground extinction as a valid variability mechanism. The variable accretion scenario allows for shorter variability timescales since the variations in luminosity occur on much smaller scales, essentially at the surface of the star, and the disk surface can react almost instantly on the changing irradiation with a higher or lower dust temperature and according brightness. We have detected substantial variations at long wavelengths in T Tau S: +26% within four days at 12.8 micron. We show that this short-term variability cannot be due to variable extinction and instead must be due to variable accretion. Using a radiative transfer model of the Sa disk we show that variable accretion can in principle also account for the much larger (several magnitude) variations observed on timescales of several years. For the long-term variability, however, also variable foreground extinction is a viable mechanism.Comment: 15 pages, 8 figures, Accepted for publication in Astronomy and Astrophysic

    Van der Waals bond lengths and electronic spectral shifts of the benzene---Kr and benzene---Xe complexes

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    Rotationally resolved UV-spectra are presented for the 610 bands of benzene---Kr and benzene---Xe complexes yielding precise rotational constants and van der Waals bond lengths for the ground and excited vibronic state, and electronic band shifts. These value complement the previously published data for the other rare gases and the various quantities have now been determined for all the benzene—rare gas complexes. Measured values of the bond length were used to calculate the band shifts from recent theoretical predictions. They are compared with the experimental values of this work

    Identification of SH Δv=1\Delta v=1 ro-vibrational lines in R And

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    We report the identification of SH Δv=1\Delta v=1 ro-vibrational lines in the published high-resolution infrared spectrum of the S-type star, R And. This is the first astronomical detection of this molecule. The lines show inverse P-Cygni profiles, indicating infall motion of the molecular layer due to stellar pulsation. A simple spherical shell model with a constant infall velocity is adopted to determine the condition of the layer. It is found that a single excitation temperature of 2200 K reproduces the observed line intensities satisfactory. SH is located in a layer from 1.0 to ~1.1 stellar radii, which is moving inward with a velocity of 9 km s-1. These results are consistent with the previous measurements of CO Δv=3\Delta v=3 transitions. The estimated molecular abundance SH/H is 1x10^-7, consistent with a thermal equilibrium calculation.Comment: 10 pages, 2 figures. Accepted for publication in ApJ Letter

    The depression in visual impairment trial (DEPVIT): trial design and protocol

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    &lt;b&gt;Background&lt;/b&gt; The prevalence of depression in people with a visual disability is high but screening for depression and referral for treatment is not yet an integral part of visual rehabilitation service provision. One reason for this may be that there is no good evidence about the effectiveness of treatments in this patient group. This study is the first to evaluate the effect of depression treatments on people with a visual impairment and co morbid depression.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Methods/design&lt;/b&gt; The study is an exploratory, multicentre, individually randomised waiting list controlled trial. Participants will be randomised to receive Problem Solving Therapy (PST), a ‘referral to the GP’ requesting treatment according to the NICE’s ‘stepped care’ recommendations or the waiting list arm of the trial. The primary outcome measure is change (from randomisation) in depressive symptoms as measured by the Beck’s Depression Inventory (BDI-II) at 6 months. Secondary outcomes include change in depressive symptoms at 3 months, change in visual function as measured with the near vision subscale of the VFQ-48 and 7 item NEI-VFQ at 3 and 6 months, change in generic health related quality of life (EQ5D), the costs associated with PST, estimates of incremental cost effectiveness, and recruitment rate estimation.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Discussion&lt;/b&gt; Depression is prevalent in people with disabling visual impairment. This exploratory study will establish depression screening and referral for treatment in visual rehabilitation clinics in the UK. It will be the first to explore the efficacy of PST and the effectiveness of NICE’s ‘stepped care’ approach to the treatment of depression in people with a visual impairment.&lt;p&gt;&lt;/p&gt

    Edificio administrativo, Isola-Suiza

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    This is an administrative building, which can accommodate 110 offices, of 1.80 x 6.00 ms, and has four storeys and a basement. It has been built on a sloping site, which enhances its functional possibilities. A modular system of design has been adopted, based on the distance of 1.80 ms, which provides great flexibility to adopt the building to uncertain future requirements. The same criterion has been followed as regards the installations: each module is independent and has its own services. The partitions between the various offices are movable, and can be positioned as required. The external aspect is simple and follows a cube pattern. The architects have attempted to express, through the appearance from without, the diversity of functions that are undertaken within. This they have been successful in achieving, without letting the observer forget that the exterior and the interior constitute an integrated whole.<br><br>Este edificio administrativo, capaz de alojar 110 despachos—módulos de 1,80x6,00 m—, consta de cuatro plantas y sótano, y se levanta sobre un terreno en pendiente que le proporciona grandes posibilidades. Se ha adoptado, en planta, un sistema de construcción modular de 1,80 m entre ejes, el cual, por desconocer las necesidades futuras, garantiza una gran flexibilidad para adaptarlo a las mismas. El mismo criterio se ha seguido respecto a las instalaciones: cada módulo es independiente y está dotado de los correspondientes servicios. Los tabiques de separación entre los diferentes despachos son móviles. El aspecto exterior obedece a una forma clara, cúbica, en la que los arquitectos han tratado de expresar, a través de las fachadas, la diversidad de funciones que tienen lugar en el interior. Y lo han conseguido acertadamente, sin hacer olvidar al espectador que el interior y el exterior forman un conjunto único

    Electroproduction of nucleon resonances

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    The unitary isobar model MAID has been extended and used for a partial wave analysis of pion photo- and electroproduction in the resonance region W < 2 GeV. Older data from the world data base and more recent experimental results from Mainz, Bates, Bonn and JLab for Q^2 up to 4.0 (GeV/c)^2 have been analyzed and the Q^2 dependence of the helicity amplitudes have been extracted for a series of four star resonances. We compare single-Q^2 analyses with a superglobal fit in a new parametrization of Maid2003 together with predictions of the hypercentral constituent quark model. As a result we find that the helicity amplitudes and transition form factors of constituent quark models should be compared with the analysis of bare resonances, where the pion cloud contributions have been subtracted.Comment: 6 pages Latex including 5 figures, Invited talk at ICTP 4th International Conference on Perspectives in Hadronic Physics, Trieste, Italy, 12-16 May 200

    Direct sampling of exponential phase moments of smoothed Wigner functions

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    We investigate exponential phase moments of the s-parametrized quasidistributions (smoothed Wigner functions). We show that the knowledge of these moments as functions of s provides, together with photon-number statistics, a complete description of the quantum state. We demonstrate that the exponential phase moments can be directly sampled from the data recorded in balanced homodyne detection and we present simple expressions for the sampling kernels. The phase moments are Fourier coefficients of phase distributions obtained from the quasidistributions via integration over the radial variable in polar coordinates. We performed Monte Carlo simulations of the homodyne detection and we demonstrate the feasibility of direct sampling of the moments and subsequent reconstruction of the phase distribution.Comment: RevTeX, 8 pages, 6 figures, accepted Phys. Rev.
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