18,764 research outputs found

    New broad 8Be nuclear resonances

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    Energies, total and partial widths, and reduced width amplitudes of 8Be resonances up to an excitation energy of 26 MeV are extracted from a coupled channel analysis of experimental data. The presence of an extremely broad J^pi = 2^+ ``intruder'' resonance is confirmed, while a new 1^+ and very broad 4^+ resonance are discovered. A previously known 22 MeV 2^+ resonance is likely resolved into two resonances. The experimental J^pi T = 3^(+)? resonance at 22 MeV is determined to be 3^-0, and the experimental 1^-? (at 19 MeV) and 4^-? resonances to be isospin 0.Comment: 16 pages, LaTe

    Sm-Nd isotopic systematics of the ancient Gneiss complex, southern Africa

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    In order to shed some new light on the question of the absolute and relative ages of the Ancient Gneiss Complex and Onverwacht Group, a Sm-Nd whole-rock and mineral isochron study of the AGC was begun. At this point, the whole-rock study of samples from the Bimodal Suite selected from those studied for their geochemical characteristics by Hunter et al., is completed. These results and their implications for the chronologic evolution of the Kaapvaal craton and the sources of these ancient rocks are discussed

    TM digital image products for applications

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    Computer compatible tapes (CCTs) of LANDSAT 4 thematic mapper (TM) digital image products are compared and reviewed. The following tape formats are discussed: (1) raw band-sequential data (CCT-BT); (2) calibrated data (CCT-AT); and (3) geometrically resampled data (CCT-PT). Each format represents different steps in the process of producing fully corrected TM data. The CCT-BT images are uncorrected radiometrically or geometrically, CCT-AT data are radiometrically calibrated, and CCT-PT images are both radiometrically and geometrically corrected

    TM digital image products for applications

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    The image characteristics of digital data generated by LANDSAT 4 thematic mapper (TM) are discussed. Digital data from the TM resides in tape files at various stages of image processing. Within each image data file, the image lines are blocked by a factor of either 5 for a computer compatible tape CCT-BT, or 4 for a CCT-AT and CCT-PT; in each format, the image file has a different format. Nominal geometric corrections which provide proper geodetic relationships between different parts of the image are available only for the CCT-PT. It is concluded that detector 3 of band 5 on the TM does not respond; this channel of data needs replacement. The empty bin phenomenon in CCT-AT images results from integer truncations of mixed-mode arithmetric operations

    The Infra‐Red Absorption Spectrum of Boron Trifluoride

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    The infra‐red absorption spectrum of BF3 has been studied under high resolution from 400 cm—1 to 3000 cm—1. The active fundamentals v2, v3 and v4 and the overtone 2v3 have been observed. The parallel fundamental v2 has been partially resolved and the value of the moment of inertia A found to be 79×10—40 g cm2. The B☒F distance is 1.29×10—8 cm. The isotope effect due to the two isotopes of boron was observed in all bands. The appearance of the unresolved bands v4 and 2v3 is shown to be greatly influenced by the interaction between vibration and rotation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70698/2/JCPSA6-7-7-455-1.pd

    Astrophysical SS factor for the 15N(p,γ)16O{}^{15}{\rm N}(p,\gamma){}^{16}{\rm O} reaction from RR-matrix analysis and asymptotic normalization coefficient for 16O15N+p{}^{16}{\rm O} \to {}^{15}{\rm N} + p. Is any fit acceptable?

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    The 15N(p,γ)16O^{15}{\rm N}(p,\gamma)^{16}{\rm O} reaction provides a path from the CN cycle to the CNO bi-cycle and CNO tri-cycle. The measured astrophysical factor for this reaction is dominated by resonant capture through two strong Jπ=1J^{\pi}=1^{-} resonances at ER=312E_{R}= 312 and 962 keV and direct capture to the ground state. Recently, a new measurement of the astrophysical factor for the 15N(p,γ)16O^{15}{\rm N}(p,\gamma)^{16}{\rm O} reaction has been published [P. J. LeBlanc {\it et al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. The analysis has been done using the RR-matrix approach with unconstrained variation of all parameters including the asymptotic normalization coefficient (ANC). The best fit has been obtained for the square of the ANC C2=539.2C^{2}= 539.2 fm1{}^{-1}, which exceeds the previously measured value by a factor of 3\approx 3. Here we present a new RR-matrix analysis of the Notre Dame-LUNA data with the fixed within the experimental uncertainties square of the ANC C2=200.34C^{2}=200.34 fm1{}^{-1}. Rather than varying the ANC we add the contribution from a background resonance that effectively takes into account contributions from higher levels. Altogether we present 8 fits, five unconstrained and three constrained. In all the fits the ANC is fixed at the previously determined experimental value C2=200.34C^{2}=200.34 fm1{}^{-1}. For the unconstrained fit with the boundary condition Bc=Sc(E2)B_{c}=S_{c}(E_{2}), where E2E_{2} is the energy of the second level, we get S(0)=39.0±1.1S(0)=39.0 \pm 1.1 keVb and normalized χ~2=1.84{\tilde \chi}^{2}=1.84, i.e. the result which is similar to [P. J. LeBlanc {\it et al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. From all our fits we get the range 33.1S(0)40.133.1 \leq S(0) \leq 40.1 keVb which overlaps with the result of [P. J. LeBlanc {\it et al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. We address also physical interpretation of the fitting parameters.Comment: Submitted to PR

    Glassy dynamics in granular compaction

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    Two models are presented to study the influence of slow dynamics on granular compaction. It is found in both cases that high values of packing fraction are achieved only by the slow relaxation of cooperative structures. Ongoing work to study the full implications of these results is discussed.Comment: 12 pages, 9 figures; accepted in J. Phys: Condensed Matter, proceedings of the Trieste workshop on 'Unifying concepts in glass physics

    Distributed utterances

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    I propose an apparatus for handling intrasentential change in context. The standard approach has problems with sentences with multiple occurrences of the same demonstrative or indexical. My proposal involves the idea that contexts can be complex. Complex contexts are built out of (“simple”) Kaplanian contexts by ordered n-tupling. With these we can revise the clauses of Kaplan’s Logic of Demonstratives so that each part of a sentence is taken in a different component of a complex context. I consider other applications of the framework: to agentially distributed utterances (ones made partly by one speaker and partly by another); to an account of scare-quoting; and to an account of a binding-like phenomenon that avoids what Kit Fine calls “the antinomy of the variable.

    Electronic structure of NiS1x_{1-x}Sex_x across the phase transition

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    We report very highly resolved photoemission spectra of NiS(1-x)Se(x) across the so-called metal-insulator transition as a function of temperature as well as composition. The present results convincingly demonstrate that the low temperature, antiferromagnetic phase is metallic, with a reduced density of states at EF_F. This decrease is possibly due to the opening of gaps along specific directions in the Brillouin zone caused by the antiferromagnetic ordering.Comment: Revtex, 4 pages, 3 postscript figure
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