1,090 research outputs found

    Structure of the Isovector Dipole Resonance in Neutron-Rich 60Ca^{60}Ca Nucleus and Direct Decay from Pygmy Resonance

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    The structure of the isovector dipole resonance in neutron-rich calcium isotope, 60Ca^{60}Ca, has been investigated by implementing a careful treatment of the differences of neutron and proton radii in the continuum random phase approximation (RPARPA). The calculations have taken into account the current estimates of the neutron skin. The estimates of the escape widths for direct neutron decay from the pygmy dipole resonance (PDRPDR) were shown rather wide, implicating a strong coupling to the continuum. The width of the giant dipole resonance (GDRGDR) was evaluated, bringing on a detailed discussion about its microscopic structure.Comment: 13 pages, 2 figures, RevTex

    Spectroscopy of 54^{54}Ti and the systematic behavior of low energy octupole states in Ca and Ti isotopes

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    Excited states of the N=32N=32 nucleus 54^{54}Ti have been studied, via both inverse-kinematics proton scattering and one-neutron knockout from 55^{55}Ti by a liquid hydrogen target, using the GRETINA γ\gamma-ray tracking array. Inelastic proton-scattering cross sections and deformation lengths have been determined. A low-lying octupole state has been tentatively identified in 54^{54}Ti for the first time. A comparison of (p,p)(p,p') results on low-energy octupole states in the neutron-rich Ca and Ti isotopes with the results of Random Phase Approximation calculations demonstrates that the observed systematic behavior of these states is unexpected.Comment: 7 pages, 8 figure

    Population of bound excited states in intermediate-energy fragmentation reactions

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    Fragmentation reactions with intermediate-energy heavy-ion beams exhibit a wide range of reaction mechanisms, ranging from direct reactions to statistical processes. We examine this transition by measuring the relative population of excited states in several sd-shell nuclei produced by fragmentation with the number of removed nucleons ranging from two to sixteen. The two-nucleon removal is consistent with a non-dissipative process whereas the removal of more than five nucleons appears to be mainly statistical.Comment: 5 pages, 6 figure

    Spectroscopy of 54^{54}Ti and the systematic behavior of low energy octupole states in Ca and Ti isotopes

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    Excited states of the N=32N=32 nucleus 54^{54}Ti have been studied, via both inverse-kinematics proton scattering and one-neutron knockout from 55^{55}Ti by a liquid hydrogen target, using the GRETINA γ\gamma-ray tracking array. Inelastic proton-scattering cross sections and deformation lengths have been determined. A low-lying octupole state has been tentatively identified in 54^{54}Ti for the first time. A comparison of (p,p)(p,p') results on low-energy octupole states in the neutron-rich Ca and Ti isotopes with the results of Random Phase Approximation calculations demonstrates that the observed systematic behavior of these states is unexpected.Comment: 7 pages, 8 figure

    Shell structure at N=28 near the dripline: spectroscopy of 42^{42}Si, 43^{43}P and 44^{44}S

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    Measurements of the N=28 isotones 42Si, 43P and 44S using one- and two-proton knockout reactions from the radioactive beam nuclei 44S and 46Ar are reported. The knockout reaction cross sections for populating 42Si and 43P and a 184 keV gamma-ray observed in 43P establish that the d_{3/2} and s_{1/2} proton orbits are nearly degenerate in these nuclei and that there is a substantial Z=14 subshell closure separating these two orbits from the d_{5/2} orbit. The increase in the inclusive two-proton knockout cross section from 42Si to 44S demonstrates the importance of the availability of valence protons for determining the cross section. New calculations of the two-proton knockout reactions that include diffractive effects are presented. In addition, it is proposed that a search for the d_{5/2} proton strength in 43P via a higher statistics one-proton knockout experiment could help determine the size of the Z=14 closure.Comment: Phys. Rev. C, in pres

    Octupole strength in the neutron-rich calcium isotopes

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    Low-lying excited states of the neutron-rich calcium isotopes 4852^{48-52}Ca have been studied via γ\gamma-ray spectroscopy following inverse-kinematics proton scattering on a liquid hydrogen target using the GRETINA γ\gamma-ray tracking array. The energies and strengths of the octupole states in these isotopes are remarkably constant, indicating that these states are dominated by proton excitations.Comment: 15 pages, 3 figure

    The Impact Of Employment On Probationer Recidivism

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    There is increasing need to understand and improve rates of recidivism in all fields associated with the Criminal Justice system. This research investigated the influence that employment status and job stability have on probationer recidivism. For this project, recidivism is defined as any arrest within four years after the termination of probation. Results from this study indicate that obtaining and sustaining employment can reduce the likelihood of recidivism in probationers. Additionally, the findings suggest that job stability is indicative of increased desistance. Findings from this study lend support to the notion that there is an employment-crime relationship. The findings of this analysis have important implications for local probation practices

    Two-neutron knockout from neutron-deficient 34^{34}Ar, 30^{30}S, and 26^{26}Si

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    Two-neutron knockout reactions from nuclei in the proximity of the proton dripline have been studied using intermediate-energy beams of neutron-deficient 34^{34}Ar, 30^{30}S, and 26^{26}Si. The inclusive cross sections, and also the partial cross sections for the population of individual bound final states of the 32^{32}Ar, 28^{28}S and 24^{24}Si knockout residues, have been determined using the combination of particle and γ\gamma-ray spectroscopy. Similar to the two-proton knockout mechanism on the neutron-rich side of the nuclear chart, these two-neutron removal reactions from already neutron-deficient nuclei are also shown to be consistent with a direct reaction mechanism.Comment: Phys. Rev. C, rapid communication, in pres
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