1,220 research outputs found

    New T=1 effective interactions for the f5/2 p3/2 p1/2 g9/2 model space; Implications for valence-mirror symmetry and seniority isomers

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    New shell model Hamiltonians are derived for the T=1 part of the residual interaction in the f5/2 p3/2 p1/2 g9/2 model space based on the analysis and fit of the available experimental data for 57Ni-78Ni isotopes and 77Cu-100Sn isotones. The fit procedure, properties of the determined effective interaction as well as new results for valence-mirror symmetry and seniority isomers for nuclei near 78Ni and 100Sn are discussed.Comment: 4 pages, 5 figure

    Proton-neutron pairing in the deformed BCS approach

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    We examine isovector and isoscalar proton-neutron pairing correlations for the ground state of even-even Ge isotopes with mass number A=64-76 within the deformed BCS approach. For N=Z 64Ge the BCS solution with only T=0 proton-neutron pairs is found. For other nuclear systems (N>Z) a coexistence of a T=0 and T=1 pairs in the BCS wave function is observed. A problem of fixing of strengths of isoscalar and isovector pairing interactions is addressed. A dependence of number of like and unlike pairs in the BCS ground state on the difference between number of neutrons and protons is discussed. We found that for nuclei with N much bigger than Z the effect of proton-neutron pairing is small but not negligible.Comment: 24 pages, 6 figure

    Investigating Tsunami-Ionospheric Coupling Efficiency

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    Coupling has been shown to exist between tsunamis and the upper atmosphere, making their detection in the total electron content (TEC) and the airglow layer possible. However, a quantitative relationship between the strength of the ionospheric signature and the sea level variation remains elusive. Here, we show the ionospheric detection of the 28 October 2012 Haida Gwaii tsunami in both the TEC and the airglow layer. Previously reported ionospheric signatures from the 11 March 2011 Tohoku tsunami are re-explored in comparison to the newer Haida Gwaii detections. Both events provide excellent test cases in the study of tsunami ionospheric coupling efficiency which is most notably affected by the observation geometry and the tsunami propagation direction. A simple a priori model based on the problem geometry is developed that predicts the relative coupling effi ciency while also incorporating the observability of the gravity wave. Predictions are compared to observations and the limitations of the model are discussed in an effort to motivate future studies.Office of Naval Research/N00014-13-1-0350Ope

    Tsunami monitoring using airglow imaging systems

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    Tsunamis generate internal gravity waves (IGWs) that propagate vertically into the atmosphere and can create detectable signatures in the ionosphere. These signatures have consistently been observed in the presence of a tsunami for over a decade in the total electron content and for over 5 years in the 630.0 nm airglow. Here, we provide a comprehensive overview on the utilization of airglow imaging systems for monitoring tsunamis. We develop the basic theory behind tsunami-ionospheric coupling from first principles and give special attention to the topic of tsunami-ionospheric coupling efficiency. This is followed by the presentation and analysis of a methodology for extracting wave parameters of tsunami-induced signatures appearing in airglow images. The methodology is applied to the 11 March 2011 Tohoku and 16 September 2015 Chile tsunamis as case studies. A previously developed geometric model that takes into account the assumed posture of tsunami-induced IGWs in the geomagnetic field and the observation geometry is shown to predict the region of the sky in which the observations were seen

    First observation of γ rays emitted from excited states south-east of Sn 132: The π g9/2-1 âš - νf7/2 multiplet of In83 132

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    For the first time, the γ decay of excited states has been observed in a nucleus situated in the quadrant south-east of doubly magic Sn132, a region in which experimental information so far is limited to ground-state properties. Six γ rays with energies of 50, 86, 103, 227, 357, and 602 keV were observed following the β-delayed neutron emission from Cd85133, populated in the projectile fission of a U238 beam at the Radioactive Isotope Beam Factory at RIKEN within the EURICA project. The new experimental information is compared to the results of a modern realistic shell-model calculation, the first one in this region very far from stability, focusing in particular on the π0g9/2-1 - ν1f7/2 particle-hole multiplet in In83132. In addition, theoretical estimates based on a scaling of the two-body matrix elements for the πh11/2-1 - νg9/2 analog multiplet in Tl127208, one major proton and one major neutron shell above, are presented. © 2016 American Physical Society

    Dominant g(9/2)^2 neutron configuration in the 4+1 state of 68Zn based on new g factor measurements

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    The gg factor of the 41+4_1^+ state in 68^{68}Zn has been remeasured with improved energy resolution of the detectors used. The value obtained is consistent with the previous result of a negative gg factor thus confirming the dominant 0g9/20g_{9/2} neutron nature of the 41+4_1^+ state. In addition, the accuracy of the gg factors of the 21+2_1^+, 22+2_2^+ and 313_1^- states has been improved an d their lifetimes were well reproduced. New large-scale shell model calculations based on a 56^{56}Ni core and an 0f5/21pg9/20f_{5/2}1pg_{9/2} model space yield a theoretical value, g(41+)=+0.008g(4_1^+) = +0.008. Although the calculated value is small, it cannot fully explain the experimental value, g(41+)=0.37(17)g(4_1^+) = -0.37(17). The magnitude of the deduced B(E2) of the 41+4_1^+ and 21+2_1^+ transition is, however, rather well described. These results demonstrate again the importance of gg factor measurements for nuclear structure determination s due to their specific sensitivity to detailed proton and neutron components in the nuclear wave functions.Comment: 7 pages, 3 figs, submitted to PL

    Core excitations across the neutron shell gap in ²⁰⁷Tl

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    The single closed-neutron-shell, one proton-hole nucleus 207Tl was populated in deep-inelastic collisions of a 208Pb beam with a 208Pb target. The yrast and near-yrast level scheme has been established up to high excitation energy, comprising an octupol

    Realistic Shell-Model Calculations for Proton-Rich N=50 Isotones

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    The structure of the N=50 isotones 98Cd, 97Ag, and 96Pd is studied in terms of shell model employing a realistic effective interaction derived from the Bonn-A nucleon-nucleon potential. The single-hole energies are fixed by resorting to an analysis of the low-energy spectra of the isotones with A>= 91. Comparison shows that our results are in very satisfactory agreement with the available experimental data. This supports confidence in the predictions of our calculationsComment: 8 pages, 3 figures, to be published on Journal of Physics

    Outcomes Following Anterior Cruciate Ligament Reconstruction with Patellar Tendon vs Hamstring Autografts: A Systematic Review of Randomized Controlled Trials with a Mean Follow-up of 15 Years

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    BACKGROUND: The two most common surgical treatment modalities for anterior cruciate ligament reconstruction (ACL), patellar tendon (PT) and hamstring tendon (HS) autografts, have been shown to have outcomes that are both similar and favorable; however, many of these are short or intermediate-term. The objective of this systematic review is to evaluate randomized controlled trials (RCTs) with a minimum 10-year follow-up data to compare the long-term outcomes of ACL reconstructions performed using PT and HS autografts. METHODS: This systematic review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A search of three databases (PubMed, Cochrane and EMBASE) was performed to identify RCTs with a minimum of 10-year follow-up that compared clinical and/or functional outcomes between PT and HS autografts. RESULTS: Four RCTs with a total of 299 patients were included in the study. The mean follow-up ranged from 10.2 to 17 years (mean, 14.79 years). No significant differences in knee laxity or clinical outcome scores were demonstrated in any of the studies. One study found that PT autografts were significantly more likely to have osteoarthritis identified by radiographic findings. Two studies found that patients with PT autografts reported increase kneeling pain, while none of the four studies reported a difference in anterior knee pain. There were no significant differences in graft failure rates. CONCLUSION: This review demonstrates no long-term difference in clinical or functional outcomes between PT and HS autografts. However, radiographic and subjective outcomes indicate that patients with PT autografts may experience greater kneeling pain and osteoarthritis. Therefore, orthopedic surgeons should consider patient-centric factors when discussing graft options with patients
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