Compression modes in nuclei: microscopic models with Skyrme interactions

The isoscalar giant monopole resonances (ISGMR) and giant dipole resonances (ISGDR) in medium-heavy nuclei are investigated in the framework of HF+RPA and HF-BCS+QRPA with Skyrme effective interactions. It is found that pairing has little effect on these modes. It is also found that the coupling of the RPA states to 2p-2h configurations results in about (or less than) 1 MeV shifts of the resonance energies and at the same time gives the correct total widths. For the ISGMR, comparison with recent data leads to a value of nuclear matter compression modulus close to 215 MeV. However, a discrepancy between calculated and measured energies of the ISGDR in $^{208}$Pb is found and remains an open problem.Comment: To appear in: ``RIKEN Symposium and Workshop on Selected Topics in Nuclear Collective Excitations'', proceedings of the meeting, RIKEN, Wako city (Japan), March 20--24, 199

The pygmy dipole strength, the neutron radius of 208{}^{208}Pb and the symmetry energy

The accurate characterization of the nuclear symmetry energy and its density dependence is one of the outstanding open problems in nuclear physics. A promising nuclear observable in order to constrain the density dependence of the symmetry energy at saturation is the neutron skin thickness of medium and heavy nuclei. Recently, a low-energy peak in the isovector dipole response of neutron-rich nuclei has been discovered that may be correlated with the neutron skin thickness. The existence of this correlation is currently under debate due to our limited experimental knowledge on the microscopic structure of such a peak. We present a detailed analysis of Skyrme Hartree-Fock (HF) plus random phase approximation (RPA) predictions for the dipole response in several neutron-rich nuclei and try to elucidate whether models of common use in nuclear physics confirm or dismiss its possible connection with the neutron skin thickness. Finally, we briefly present theoretical results for parity violating electron scattering on ${}^{208}$Pb at the conditions of the PREx experiment and discuss the implications for the neutron skin thickness of ${}^{208}$Pb and the slope of the symmetry energy.Comment: Contribution to the 2nd Iberian Nuclear Astrophysics Meeting on Compact Stars proceeding

First Measurement of Electron Neutrino Appearance in NOvA

We report results from the first search for nu(mu) -\u3e nu(e) transitions by the NOvA experiment. In an exposure equivalent to 2.74 x 10(20) protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99 +/- 0.11 (syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07 +/- 0.14 (syst). The 3.3 sigma excess of events observed in the primary analysis disfavors 0.1 pi \u3c delta(CP) \u3c 0.5 pi in the inverted mass hierarchy at the 90% C.L

First measurement of muon-neutrino disappearance in NOvA

This paper reports the first measurement using the NOvA detectors of nu(mu) disappearance in a nu(mu) beam. The analysis uses a 14 kton-equivalent exposure of 2.74 x 10(20) protons-on-target from the Fermilab NuMI beam. Assuming the normal neutrino mass hierarchy, we measure Delta m(32)(2) = (2.52(-0.18)(+0.20)) x 10(-3) eV(2) and sin(2) theta(23) in the range 0.38-0.65, both at the 68% confidence level, with two statistically degenerate best-fit points at sin(2) theta(23) = 0.43 and 0.60. Results for the inverted mass hierarchy are also presented

Effects of finite width of excited states on heavy-ion sub-barrier fusion reactions

We discuss the effects of coupling of the relative motion to nuclear collective excitations which have a finite lifetime on heavy-ion fusion reactions at energies near and below the Coulomb barrier. Both spreading and escape widths are explicitly taken into account in the exit doorway model. The coupled-channels equations are numerically solved to show that the finite resonance width always hinders fusion cross sections at subbarrier energies irrespective of the relative importance between the spreading and the escape widths. We also show that the structure of fusion barrier distribution is smeared due to the spreading of the strength of the doorway state.Comment: 13 pages, 3 figures, Submitted to Physical Review

Effect of the momentum dependence of nuclear symmetry potential on the transverse and elliptic flows

In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, effect of the momentum dependence of nuclear symmetry potential on nuclear transverse and elliptic flows in the neutron-rich reaction $^{132}$Sn+$^{124}$Sn at a beam energy of 400 MeV/nucleon is studied. We find that the momentum dependence of nuclear symmetry potential affects the rapidity distribution of the free neutron to proton ratio, the neutron and the proton transverse flows as a function of rapidity. The momentum dependence of nuclear symmetry potential affects the neutron-proton differential transverse flow more evidently than the difference of neutron and proton transverse flows as well as the difference of proton and neutron elliptic flows. It is thus better to probe the symmetry energy by using the difference of neutron and proton flows since the momentum dependence of nuclear symmetry potential is still an open question. And it is better to probe the momentum dependence of nuclear symmetry potential by using the neutron-proton differential transverse flow and the rapidity distribution of the free neutron to proton ratio.Comment: 6 pages, 6 figures, to be published by EPJ

The Effect of the Pairing Interaction on the Energies of Isobar Analog Resonances in 112−124^{112-124}Sb and Isospin Admixture in 100−124^{100-124}Sn Isotopes

In the present study, the effect of the pairing interaction and the isovector correlation between nucleons on the properties of the isobar analog resonances (IAR) in $^{112-124}$Sb isotopes and the isospin admixture in $^{100-124}$Sn isotopes is investigated within the framework of the quasiparticle random phase approximation (QRPA). The form of the interaction strength parameter is related to the shell model potential by restoring the isotopic invariance of the nuclear part of the total Hamiltonian. In this respect, the isospin admixtures in the $^{100-124}$Sn isotopes are calculated, and the dependence of the differential cross section and the volume integral $J_{F}$ for the Sn($^{3}$He,t)Sb reactions at E($^{3}$He)$=200$ MeV occurring by the excitation of IAR on mass number A is examined. Our results show that the calculated value for the isospin mixing in the $^{100}$Sn isotope is in good agreement with Colo et al.'s estimates $(4-5$, and the obtained values for the volume integral change within the error range of the value reported by Fujiwara et al. (53$\pm$5 MeV fm$^{3}$). Moreover, it is concluded that although the differential cross section of the isobar analog resonance for the ($^{3}$He,t) reactions is not sensitive to pairing correlations between nucleons, a considerable effect on the isospin admixtures in $N\approx Z$ isotopes can be seen with the presence of these correlations.Comment: 16 pages, 5 EPS figures and 2 tables, Late

Dizajniranje i vrednovanje okularnih umetaka moksifloksacin hidroklorida

The objective of the present investigation was to prepare and evaluate ocular inserts of moxifloxacin. An ocular insert was made from an aqueous dispersion of moxifloxacin, sodium alginate, polyvinyl alcohol, and dibutyl phthalate by the film casting method. The ocular insert (5.5 mm diameter) was cross-linked by CaCl2 and was coated with Eudragit S-100, RL-100, RS-100, E-100 or Eudragit L-100. The in vitro drug drainage/permeation studies were carried out using an all-glass modified Franz diffusion cell. The drug concentration and mucoadhesion time of the ocular insert were found satisfactory. Cross-linking and coating with polymers extended the drainage from inserts. The cross-linked ocular insert coated with Eudragit RL-100 showed maximum drug permeation compared to other formulations.Cilj rada bio je priprava i evaluacija okularnih umetaka moksifloksacina. Okularni umetak izrađen je od vodene suspenzije moksifloksacina, natrijevog alginata, polivinilnog alkohola i dibutil-ftalata metodom odlijevanja filma. Okularni umetak (promjera 5,5 mm) umrežen je pomoću CaCl2 i obložen Eudragitom S-100, RL-100, RS-100, E-100 ili Eudragit L-100. In vitro drenaža/permeacija lijeka proučavana je koristeći staklenu modificiranu Franzovu difuzijsku ćeliju. Koncentracija lijeka i vrijeme mukoadhezije okularnih umetaka bili su zadovoljavajući. Umrežavanje i oblaganje polimerima produljilo je drenažu iz umetaka. Umreženi okularni umetci obloženi s Eudragit RL-100 pokazali su veću permeaciju lijeka u odnosu na ostale pripravke