622 research outputs found

    Ground--state energies and widths of 5^5He and 5^5Li

    Full text link
    We extract energies and widths of the ground states of 5^5He and 5^5Li from recent single--level R--matrix fits to the spectra of the 3^3H(d,({\rm d},\gamma)5^5He and the 3^3He(d,({\rm d},\gamma)5^5Li reactions. The widths obtained differ significantly from the formal R--matrix values but they are close to those measured as full widths at half maxima of the spectra in various experiments. The energies are somewhat lower than those given by usual estimates of the peak positions. The extracted values are close to the S--matrix poles calculated previously from the multi--term analyses of the N-4^4He elastic scattering data.Comment: 3 pages, no figures, uses revtex.sty, accepted for publication in PRC, uuencoded postscript and tex-files available at ftp://is1.kph.tuwien.ac.at/pub/ohu/fwidth.u

    Energy Levels of Light Nuclei A = 7

    Get PDF
    Abstract: An evaluation of A = 5-1

    E2 properties of nuclei far from stability and the proton-halo problem of 8B

    Full text link
    E2 properties of A=6--10 nuclei, including those of nuclei far from stability, are studied by a (0+2)(0+2)\hbar\omega shell-model calculation which includes E2 core-polarization effects explicitly. The quadrupole moments and the E2 transition strengths in A=6--10 nuclei are described quite well by the present calculation. This result indicates that the relatively large value of the quadrupole moment of 8^8B can be understood without introducing the proton-halo in 8^8B. An interesting effect of the 22\hbar\omega core-polarization is found for effective charges used in the 00\hbar\omega shell model; although isoscalar effective-charges are almost constant as a function of nucleus, appreciable variations are needed for isovector effective-charges which play important roles in nuclei with high isospin-values.Comment: (LaTeX, 23 pages

    Energy Levels of Light Nuclei A = 7

    Get PDF
    Abstract: An evaluation of A = 5-10 was published in Nuclear Physics 78 (1966), p. 1. This version of A = 7 differs from the published version in that we have corrected some errors discovered after the article went to press. Figures and introductory tables have been omitted from this manuscript. Reference key numbers have been changed to the TUNL/NNDC format

    Properties of 8^{8}Be and 12^{12}C deduced from the folding--potential model

    Full text link
    The \alpha--\alpha differential cross sections are analyzed in the optical model using a double--folded potential. With the knowledge of this potential bound and resonance--state properties of \alpha--cluster states in 8^{8}Be and 12^{12}C as well as astrophysical S--factors of 4^{4}He(\alpha,\gamma)8^{8}Be and 8^{8}Be(\alpha,\gamma)12^{12}C are calculated. \Gamma_{\gamma}--widths and B(E2)--values are deduced.Comment: 2 pages LaTeX, 2 figures can be obtained from the author

    Isospin Effects in Nuclear Multifragmentation

    Full text link
    We develop an improved Statistical Multifragmentation Model that provides the capability to calculate calorimetric and isotopic observables with precision. With this new model we examine the influence of nuclear isospin on the fragment elemental and isotopic distributions. We show that the proposed improvements on the model are essential for studying isospin effects in nuclear multifragmentation. In particular, these calculations show that accurate comparisons to experimental data require that the nuclear masses, free energies and secondary decay must be handled with higher precision than many current models accord.Comment: 46 pages, 16 figure

    Cluster states in nuclei as representations of a U(n+1) group

    Full text link
    We propose a description of cluster states in nuclei in terms of representations of unitary algebras U(n+1), where n is the number of space degrees of freedom. Within this framework, a variety of situations including both vibrational and rotational spectra, soft and rigid configurations, identical and non-identical constituents can be described. As an example, we show how the method can be used to study alpha-clustering configurations in 12C with point group symmetry D(3h).Comment: 5 pages, 2 figures, Phys. Rev. C, in pres

    Nuclear halo and its scaling laws

    Full text link
    We have proposed a procedure to extract the probability for valence particle being out of the binding potential from the measured nuclear asymptotic normalization coefficients. With this procedure, available data regarding the nuclear halo candidates are systematically analyzed and a number of halo nuclei are confirmed. Based on these results we have got a much relaxed condition for nuclear halo occurrence. Furthermore, we have presented the scaling laws for the dimensionless quantity /R2/R^{2} of nuclear halo in terms of the analytical expressions of the expectation value for the operator r2r^{2} in a finite square-well potential.Comment: 14 pages, 3 figure

    An Attempt to Study T=2 States in 16-N

    Get PDF
    This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

    Direct radiative capture of p-wave neutrons

    Get PDF
    The neutron direct radiative capture (DRC) process is investigated, highlighting the role of incident p-wave neutrons. A set of calculations is shown for the 12-C(n,gamma) process at incoming neutron energies up to 500 keV, a crucial region for astrophysics. The cross section for neutron capture leading to loosely bound s, p and d orbits of 13-C is well reproduced by the DRC model demonstrating the feasibility of using this reaction channel to study the properties of nuclear wave functions on and outside the nuclear surface. A sensitivity analysis of the results on the neutron-nucleus interaction is performed for incident s- as well as p-waves. It turned out that the DRC cross section for p-wave neutrons is insensitive to this interaction, contrary to the case of incident s-wave neutrons. PACS number(s): 25.40Lw,21.10Gv,23.40.HcComment: 16 pages, REVTeX file, PostScript file, .dvi fil
    corecore