1,703 research outputs found

    Dependence of Maximum Trappable Field on Superconducting Nb3Sn Cylinder Wall Thickness

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    Uniform dipole magnetic fields from 1.9 to 22.4 kOe were permanently trapped, with high fidelity to the original field, transversely to the axes of hollow Nb3Sn superconducting cylinders. These cylinders were constructed by helically wrapping multiple layers of superconducting ribbon around a mandrel. This is the highest field yet trapped, the first time trapping has been reported in such helically wound taped cylinders, and the first time the maximum trappable field has been experimentally determined as a function of cylinder wall thickness.Comment: 8 pages, 4 figures, 1 table. PACS numbers: 74.60.Ge, 74.70.Ps, 41.10.Fs, 85.25.+

    Lead levels in fur of rats treated with inorganic lead measured by inductively coupled argon plasma mass spectrometry

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    The aim of this study was to investigate the relationship between continuous lead exposure and the concentration of this metal in fur. The two main questions we wanted to answer were: 1) Are the fur lead concentrations different according to exposure level? 2) Is the kinetics of lead concentration linear in different compartments

    Critical Review of Theoretical Models for Anomalous Effects (Cold Fusion) in Deuterated Metals

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    We briefly summarize the reported anomalous effects in deuterated metals at ambient temperature, commonly known as "Cold Fusion" (CF), with an emphasis on important experiments as well as the theoretical basis for the opposition to interpreting them as cold fusion. Then we critically examine more than 25 theoretical models for CF, including unusual nuclear and exotic chemical hypotheses. We conclude that they do not explain the data.Comment: 51 pages, 4 Figure

    The influence of direct DD-meson production to the determination on the nucleon strangeness asymmetry via dimuon events in neutrino experiments

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    Experimentally, the production of oppositely charged dimuon events by neutrino and anti-neutrino deep inelastic scattering (DIS) is used to determine the strangeness asymmetry inside a nucleon. Here we point out that the direct production of DD-meson in DIS may make substantial influence to the measurement of nucleon strange distributions. The direct DD-meson production is via the heavy quark recombination (HQR) and via the light quark fragmentation from perturbative QCD (LQF-P). To see the influence precisely, we compute the direct DD-meson productions via HQR and LQF-P quantitatively and estimate their corrections to the analysis of the strangeness asymmetry. The results show that HQR has stronger effect than LQF-P does, and the former may influence the experimental determination of the nucleon strangeness asymmetry.Comment: 9 latex pages, 7 figure

    Muonic hydrogen cascade time and lifetime of the short-lived 2S2S state

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    Metastable 2S{2S} muonic-hydrogen atoms undergo collisional 2S{2S}-quenching, with rates which depend strongly on whether the ÎŒp\mu p kinetic energy is above or below the 2S→2P{2S}\to {2P} energy threshold. Above threshold, collisional 2S→2P{2S} \to {2P} excitation followed by fast radiative 2P→1S{2P} \to {1S} deexcitation is allowed. The corresponding short-lived ÎŒp(2S)\mu p ({2S}) component was measured at 0.6 hPa H2\mathrm{H}_2 room temperature gas pressure, with lifetime τ2Sshort=165−29+38\tau_{2S}^\mathrm{short} = 165 ^{+38}_{-29} ns (i.e., λ2Squench=7.9−1.6+1.8×1012s−1\lambda_{2S}^\mathrm{quench} = 7.9 ^{+1.8}_{-1.6} \times 10^{12} \mathrm{s}^{-1} at liquid-hydrogen density) and population Ï”2Sshort=1.70−0.56+0.80\epsilon_{2S}^\mathrm{short} = 1.70^{+0.80}_{-0.56} % (per ÎŒp\mu p atom). In addition, a value of the ÎŒp\mu p cascade time, TcasÎŒp=(37±5)T_\mathrm{cas}^{\mu p} = (37\pm5) ns, was found.Comment: 4 pages, 3 figure

    Early ultraviolet emission in the Type Ia supernova LSQ12gdj: No evidence for ongoing shock interaction

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    We present photospheric-phase observations of LSQ12gdj, a slowly-declining, UV-bright Type Ia supernova. Classified well before maximum light, LSQ12gdj has extinction-corrected absolute magnitude MB=−19.8M_B = -19.8, and pre-maximum spectroscopic evolution similar to SN 1991T and the super-Chandrasekhar-mass SN 2007if. We use ultraviolet photometry from Swift, ground-based optical photometry, and corrections from a near-infrared photometric template to construct the bolometric (1600-23800 \AA) light curve out to 45 days past BB-band maximum light. We estimate that LSQ12gdj produced 0.96±0.070.96 \pm 0.07 M⊙M_\odot of 56^{56}Ni, with an ejected mass near or slightly above the Chandrasekhar mass. As much as 27% of the flux at the earliest observed phases, and 17% at maximum light, is emitted bluewards of 3300 \AA. The absence of excess luminosity at late times, the cutoff of the spectral energy distribution bluewards of 3000 \AA, and the absence of narrow line emission and strong Na I D absorption all argue against a significant contribution from ongoing shock interaction. However, up to 10% of LSQ12gdj's luminosity near maximum light could be produced by the release of trapped radiation, including kinetic energy thermalized during a brief interaction with a compact, hydrogen-poor envelope (radius <1013< 10^{13} cm) shortly after explosion; such an envelope arises generically in double-degenerate merger scenarios.Comment: 18 pages, 10 figures, accepted to MNRAS; v2 accepted version. Spectra available on WISEReP (http://www.weizmann.ac.il/astrophysics/wiserep/). Natural-system photometry and bolometric light curve available as online tables in MNRAS versio

    Constraining Type Ia supernova models: SN 2011fe as a test case

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    The nearby supernova SN 2011fe can be observed in unprecedented detail. Therefore, it is an important test case for Type Ia supernova (SN Ia) models, which may bring us closer to understanding the physical nature of these objects. Here, we explore how available and expected future observations of SN 2011fe can be used to constrain SN Ia explosion scenarios. We base our discussion on three-dimensional simulations of a delayed detonation in a Chandrasekhar-mass white dwarf and of a violent merger of two white dwarfs-realizations of explosion models appropriate for two of the most widely-discussed progenitor channels that may give rise to SNe Ia. Although both models have their shortcomings in reproducing details of the early and near-maximum spectra of SN 2011fe obtained by the Nearby Supernova Factory (SNfactory), the overall match with the observations is reasonable. The level of agreement is slightly better for the merger, in particular around maximum, but a clear preference for one model over the other is still not justified. Observations at late epochs, however, hold promise for discriminating the explosion scenarios in a straightforward way, as a nucleosynthesis effect leads to differences in the 55Co production. SN 2011fe is close enough to be followed sufficiently long to study this effect.Comment: Accepted for publication in The Astrophysical Journal Letter

    Atmospheric extinction properties above Mauna Kea from the Nearby Supernova Factory spectro-photometric data set

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    We present a new atmospheric extinction curve for Mauna Kea spanning 3200--9700 \AA. It is the most comprehensive to date, being based on some 4285 standard star spectra obtained on 478 nights spread over a period of 7 years obtained by the Nearby SuperNova Factory using the SuperNova Integral Field Spectrograph. This mean curve and its dispersion can be used as an aid in calibrating spectroscopic or imaging data from Mauna Kea, and in estimating the calibration uncertainty associated with the use of a mean extinction curve. Our method for decomposing the extinction curve into physical components, and the ability to determine the chromatic portion of the extinction even on cloudy nights, is described and verified over the wide range of conditions sampled by our large dataset. We demonstrate good agreement with atmospheric science data obtain at nearby Mauna Loa Observatory, and with previously published measurements of the extinction above Mauna Kea.Comment: 22 pages, 24 figures, 6 table
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