7,126 research outputs found

    The Giant Monopole Resonance in Pb isotopes

    Full text link
    The extraction of the nuclear incompressibility from the isoscalar giant monopole resonance (GMR) measurements is analysed. Both pairing and mutually enhanced magicity (MEM) effects play a role in the shift of the GMR energy between the doubly closed shell 208^{208}Pb nucleus and other Pb isotopes. Pairing effects are microscopically predicted whereas the MEM effect is phenomenologically evaluated. Accurate measurements of the GMR in open-shell Pb isotopes are called for.Comment: 4 page

    Symmetry energy from the nuclear collective motion: constraints from dipole, quadrupole, monopole and spin-dipole resonances

    Full text link
    The experimental and theoretical studies of Giant Resonances, or more generally of the nuclear collective vibrations, are a well established domain in which sophisticated techniques have been introduced and firm conclusions reached after an effort of several decades. From it, information on the nuclear equation of state can be extracted, albeit not far from usual nuclear densities. In this contribution, which complements other contributions appearing in the current volume, we survey some of the constraints that have been extracted recently concerning the parameters of the nuclear symmetry energy. Isovector modes, in which neutrons and protons are in opposite phase, are a natural source of information and we illustrate the values of symmetry energy around saturation deduced from isovector dipole and isovector quadrupole states. The isotopic dependence of the isoscalar monopole energy has also been suggested to provide a connection to the symmetry energy: relevant theoretical arguments and experimental results are thoroughly discussed. Finally, we consider the case of the charge-exchange spin-dipole excitations in which the sum rule associated with the total strength gives in principle access to the neutron skin and thus, indirectly, to the symmetry energy.Comment: Updated version, with small corrections based on comments/suggestions from the referee. 12 pages, 9 figures; submitted to EPJA "Special Issue on Symmetry Energy

    The asymmetry term in the nuclear-matter incompressibility from measurements on the giant monopole resonance: An Update

    Full text link
    We have investigated the isoscalar giant monopole resonances (ISGMR) in 112124^{112-124}Sn and 106116^{106-116}Cd nuclei using inelastic scattering of 386-MeV α\alpha-particles at extremely forward angles, including 0^\circ. The strength distributions for various multipoles were extracted by a multipole decomposition analysis based on the expected angular distributions of the respective multipoles. From the ISGMR results, a value of Kτ500K_{\tau} \sim -500 MeV is obtained for the asymmetry term in the nuclear incompressibility.Comment: Zakopane Conference on Nuclear Physics: Extremes of the Nuclear Landscape, 45th Zakopane Schools of Physics, 30. August- 5. September 2010, Zakopane, Polan

    Where we stand on structure dependence of ISGMR in the Zr-Mo region: Implications on K_\infty

    Get PDF
    Isoscalar giant resonances, being the archetypal forms of collective nuclear behavior, have been studied extensively for decades with the goal of constraining bulk nuclear properties of the equation of state, as well as for modeling dynamical behaviors within stellar environments. An important such mode is the isoscalar electric giant monopole resonance (ISGMR) that can be understood as a radially symmetric density vibration within the saturated nuclear volume. The field has a few key open questions, which have been proposed and remain unresolved. One of the more provocative questions is the extra high-energy strength in the A90A\approx 90 region, which manifested in large percentages of the E0E0 sum rule in 92^{92}Zr and 92^{92}Mo above the main ISGMR peak. The purpose of this article is to introduce these questions within the context of experimental investigations into the phenomena in the zirconium and molybdenum isotopic chains, and to address, via a discussion of previously published and preliminary results, the implications of recent experimental efforts on extraction of the nuclear incompressibility from this data.Comment: 9 pages, 7 figures, invited to be submitted to a special issue of EPJA honoring Prof. P. F. Bortigno

    Effect of pairing correlations on incompressibility and symmetry energy in nuclear matter and finite nuclei

    Get PDF
    The role of superfluidity in the incompressibility and in the symmetry energy is studied in nuclear matter and finite nuclei. Several pairing interactions are used: surface, mixed and isovector dependent. Pairing has a small effect on the nuclear matter incompressibility at saturation density, but the effects are significant at lower densities. The pairing effect on the centroid energy of the isoscalar Giant Monopole Resonance (GMR) is also evaluated for Pb and Sn isotopes by using a microscopic constrained-HFB approach, and found to change at most by 10% the nucleus incompressibility KAK_A. It is shown by using the Local Density Approximation (LDA) that most of the pairing effect on the GMR centroid come from the low-density nuclear surface.Comment: 9 pages, 6 figure

    Early postnatal caloric restriction protects adult male intrauterine growth-restricted offspring from obesity.

    Get PDF
    Postnatal ad libitum caloric intake superimposed on intrauterine growth restriction (IUGR) is associated with adult-onset obesity, insulin resistance, and type 2 diabetes mellitus (T2DM). We hypothesized that this paradigm of prenatal nutrient deprivation-induced programming can be reversed with the introduction of early postnatal calorie restriction. Ten-month-old male rats exposed to either prenatal nutrient restriction with ad libitum postnatal intake (IUGR), pre- and postnatal nutrient restriction (IPGR), or postnatal nutrient restriction limited to the suckling phase (50% from postnatal [PN]1 to PN21) (PNGR) were compared with age-matched controls (CON). Visceral adiposity, metabolic profile, and insulin sensitivity by hyperinsulinemic-euglycemic clamps were examined. The 10-month-old male IUGR group had a 1.5- to 2.0-fold increase in subcutaneous and visceral fat (P < 0.0002) while remaining euglycemic, insulin sensitive, inactive, and exhibiting metabolic inflexibility (Vo(2)) versus CON. The IPGR group remained lean, euglycemic, insulin sensitive, and active while maintaining metabolic flexibility. The PNGR group was insulin sensitive, similar to IPGR, but less active while maintaining metabolic flexibility. We conclude that IUGR resulted in obesity without insulin resistance and energy metabolic perturbations prior to development of glucose intolerance and T2DM. Postnatal nutrient restriction superimposed on IUGR was protective, restoring metabolic normalcy to a lean and active phenotype

    Achieving Good Angular Resolution in 3D Arc Diagrams

    Full text link
    We study a three-dimensional analogue to the well-known graph visualization approach known as arc diagrams. We provide several algorithms that achieve good angular resolution for 3D arc diagrams, even for cases when the arcs must project to a given 2D straight-line drawing of the input graph. Our methods make use of various graph coloring algorithms, including an algorithm for a new coloring problem, which we call localized edge coloring.Comment: 12 pages, 5 figures; to appear at the 21st International Symposium on Graph Drawing (GD 2013

    Macroscopic Quantum Coherence in a Magnetic Nanoparticle Above the Surface of a Superconductor

    Full text link
    We study macroscopic quantum tunneling of the magnetic moment in a single-domain particle placed above the surface of a superconductor. Such a setup allows one to manipulate the height of the energy barrier, preserving the degeneracy of the ground state. The tunneling amplitude and the effect of the dissipation in the superconductor are computed.Comment: RevTeX, 4 pages, 1 figure. Submitted to Phys. Rev. Let

    High-spin structure and Band Termination in 103^{103}Cd

    Full text link
    Excited states of the neutron deficient 103^{103}Cd nucleus have been investigated via the 72^{72}Ge(35^{35}Cl, p3n) reaction at beam energy of 135 MeV by use of in-beam spectroscopic methods. Gamma rays depopulating the excited states were detected using the Gammasphere spectrometer with high-fold γ\gamma-ray coincidences. A quadrupole γ\gamma-ray coincidence analysis (γ4\gamma^{4}) has been used to extend the known level scheme. The positive parity levels have been established up to J=35/2J = 35/2\hbar and Ex=7.071E_{x} = 7.071 MeV. In addition to the observation of highly-fragmented level scheme belonging to the positive-parity sequences at Ex_{x}\sim 5 MeV, the termination of a negative-parity sequence connected by E2E2 transitions has been established at J=47/2J = 47/2 \hbar and Ex=11.877E_{x} = 11.877 MeV. The experimental results corresponding to both the positive- and negative-parity sequences have been theoretically interpreted in the framework of the core particle coupling model. Evidence is presented for a shape change from collective prolate to non-collective oblate above the Jπ=39/2J^{\pi} = 39/2^{-} (8011 keV) level and for a smooth termination of the negative-parity band.Comment: 19 pages, 8 figures. Submitted to Phys. Rev.
    corecore