1,048 research outputs found

    First Characterization of the Ultra-Shielded Chamber in the Low-noise Underground Laboratory (LSBB) of Rustrel Pays d'Apt

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    In compliance with international agreements on nuclear weapons limitation, the French ground-based nuclear arsenal has been decommissioned in its totality. One of its former underground missile control centers, located in Rustrel, 60 km east of Avignon (Provence) has been converted into the ``Laboratoire Souterrain \`a Bas Bruit de Rustrel-Pays d'Apt'' (LSBB). The deepest experimental hall (500 m of calcite rock overburden) includes a 100 m2^{2} area of sturdy flooring suspended by and resting on shock absorbers, entirely enclosed in a 28 m-long, 8 m-diameter, 1 cm-thick steel Faraday cage. This results in an unparalleled combination of shielding against cosmic rays, acoustic, seismic and electromagnetic noise, which can be exploited for rare event searches using ultra low-temperature and superconducting detectors. The first characterization measurements in this unique civilian site are reported. For more info see http://home.cern.ch/collar/RUSTREL/rustrel.htmlComment: Homepage and quoted hyperlinks have been updated: see http://home.cern.ch/collar/RUSTREL/rustrel.htm

    Prospects For Identifying Dark Matter With CoGeNT

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    It has previously been shown that the excess of events reported by the CoGeNT collaboration could be generated by elastically scattering dark matter particles with a mass of approximately 5-15 GeV. This mass range is very similar to that required to generate the annual modulation observed by DAMA/LIBRA and the gamma rays from the region surrounding the Galactic Center identified within the data of the Fermi Gamma Ray Space Telescope. To confidently conclude that CoGeNT's excess is the result of dark matter, however, further data will likely be needed. In this paper, we make projections for the first full year of CoGeNT data, and for its planned upgrade. Not only will this body of data more accurately constrain the spectrum of nuclear recoil events, and corresponding dark matter parameter space, but will also make it possible to identify seasonal variations in the rate. In particular, if the CoGeNT excess is the product of dark matter, then one year of CoGeNT data will likely reveal an annual modulation with a significance of 2-3σ\sigma. The planned CoGeNT upgrade will not only detect such an annual modulation with high significance, but will be capable of measuring the energy spectrum of the modulation amplitude. These measurements will be essential to irrefutably confirming a dark matter origin of these events.Comment: 6 pages, 6 figure

    Max E. G. Bartels and the Javan lapwing Vanellus macropterus

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    The kinetic dark-mixing in the light of CoGENT and XENON100

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    Several string or GUT constructions motivate the existence of a dark U(1)_D gauge boson which interacts with the Standard Model only through its kinetic mixing. We compute the dark matter abundance in such scenario and the constraints in the light of the recent data from CoGENT, CDMSII and XENON100. We show in particular that a region with relatively light WIMPS, M_{Z_D}< 40 GeV and a kinetic mixing 10^-4 < delta < 10^-3 is not yet excluded by the last experimental data and seems to give promising signals in a near future. We also compute the value of the kinetic mixing needed to explain the DAMA/CoGENT/CRESST excesses and find that for M_{Z_D}< 30 GeV, delta ~ 10^-3 is sufficient to fit with the data.Comment: 6 pages, 5figure

    Aktivität und Vorkommen geflügelter Blattläuse auf Freilandpaprika in Spanien

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    Horizontal mosaic-green-tile traps were placed in various pepper-growing areas of Spain: Aranjuez and Arganda del Rey (Madrid), Balboa (Badajoz), Cadreita (Pamplona), Mendavia and Sartaguda (Logroño), Montañana (Zaragoza), Pueblo Nuevo (Valencia) and Torrepacheco (Murcia). These mosaic-greentraps resembled much better the pepper canopy than the commonly used yellow water traps, as indicated by absorbance spectrophotometry. Sampling was extended throughout the pepper crop cycle during 1990, 1991 and 1992. Over that time, 14,363 aphids, belonging to 99 species/taxa were captured. Aphis was the principal genus captured: 57.5 % of the total (17 % belonging to the species Aphis fabae (Scopoli)). Other abundant species were: Myzus (Nectarosiphon) persicae (Sulzer) (7.46 %), Diuraphis noxia (Mordvilko) (5.23 %), Brachycaudus spp. (3.73 %), Sitobion avenae (F.) (2.51 %), Macrosiphum euphorbiae (Thomas) (2.46 %), Rhopalosiphum spp. (2.20 %) and Therioaphis spp. (1.99 %). The species included in the genus Aphis were the most abundant in all the regions sampled, although M. (N.) persicae was also predominant in the Zaragoza and Pamplona region, and D. noxia was frequently found in the Madrid region. A first aphid peak was observed soon after transplanting (May–June) in most of the regions and years sampled.Horizontale mosaikgrüne Farbfallen wurden in verschiedenen Paprika-Anbaugebieten in Spanien aufgestellt: Aranjuez und Arganda del Rey (Madrid), Balbao (Badajoz), Cadreita (Pamplona), Mendavia und Sartaguda (Logroño), Montañana (Zaragoza), Pueblo Nuevo (Valencia) und Torrepacheco (Murcia). Diese mosaikgrünen Fallen ähnelten sehr viel besser den Farben des Paprikabestandes als die üblicherweise eingesetzten gelben Wasserfallen wie durch Absorptionsspektrometrie festgestellt wurde. Die Probennahmen erfolgten während der ganzen Wachstumsphasen des Paprikas in den Jahren 1990, 1991 und 1992. In diesen Zeiträumen konnten 14363 Blattläuse gefangen werden, die 99 Arten/Taxa angehörten. Die Gattung Aphis wurde mit 57,5 % am häufigsten gefangen, 17 % gehörten zur Art Aphis fabae (Scopoli). Andere häufig vorkommende Arten waren: Myzus (Nectarosiphon) persicae (Sulzer) (7,46 %), Diuraphis noxia (Mordvilko) (5,23 %), Brachycaudus spp. (3,73 %), Sitobion avenae (F.) (2,51 %), Macrosiphum euphorbiae (Thomas) (2,46 %), Rhopalosiphum spp. (2,20 %) und Therioaphis spp. (1,99 %). Die zur Gattung Aphis gehörenden Arten waren in allen beprobten Regionen am häufigsten, obgleich M. (N.) persicae in den Regionen Zaragoza und Pamplona auch sehr häufig vorkam. D. noxia trat häufig in der Madrider Region auf. Ein erster Höhehoug punkt des Blattlausaufretens wurde in den meisten Regionen und Jahren schon bald nach dem Auspflanzen (Mai–Juni) beobachtet.This work was supported by the Interministerial Commision for Science and Technology of Spain (Comisión Interministerial de Ciencia y Tecnología, grant AGR91-0448)..Peer reviewe

    Superheated Microdrops as Cold Dark Matter Detectors

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    It is shown that under realistic background considerations, an improvement in Cold Dark Matter sensitivity of several orders of magnitude is expected from a detector based on superheated liquid droplets. Such devices are totally insensitive to minimum ionizing radiation while responsive to nuclear recoils of energies ~ few keV. They operate on the same principle as the bubble chamber, but offer unattended, continuous, and safe operation at room temperature and atmospheric pressure.Comment: 15 pgs, 4 figures include

    The smallest eigenvalue of Hankel matrices

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    Let H_N=(s_{n+m}),n,m\le N denote the Hankel matrix of moments of a positive measure with moments of any order. We study the large N behaviour of the smallest eigenvalue lambda_N of H_N. It is proved that lambda_N has exponential decay to zero for any measure with compact support. For general determinate moment problems the decay to 0 of lambda_N can be arbitrarily slow or arbitrarily fast. In the indeterminate case, where lambda_N is known to be bounded below by a positive constant, we prove that the limit of the n'th smallest eigenvalue of H_N for N tending to infinity tends rapidly to infinity with n. The special case of the Stieltjes-Wigert polynomials is discussed
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