Effects of phonon-phonon coupling on low-lying states in neutron-rich Sn isotopes

Starting from an effective Skyrme interaction we present a method to take into account the coupling between one- and two-phonon terms in the wave functions of excited states. The approach is a development of a finite rank separable approximation for the quasiparticle RPA calculations proposed in our previous work. The influence of the phonon-phonon coupling on energies and transition probabilities for the low-lying quadrupole and octupole states in the neutron-rich Sn isotopes is studied.Comment: 18 page

Separabelized Skyrme Interactions and Quasiparticle RPA

A finite rank separable approximation for the quasiparticle RPA with Skyrme interactions is applied to study the low lying quadrupole and octupole states in some S isotopes and giant resonances in some spherical nuclei. It is shown that characteristics calculated within the suggested approach are in a good agreement with available experimental data.Comment: 12 pages, 2 figures, proceedings of the Seventh School-Seminar on Heavy Ion Physics, Dubna, Russia, May 27-June 1, 2002; to appear in Physics of Atomic Nucle

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Quasiparticle RPA with finite rank approximation for Skyrme interactions

A finite rank separable approximation for the particle-hole RPA calculations with Skyrme interactions is extended to take into account the pairing. As an illustration of the method energies and transition probabilities for the quadrupole and octupole excitations in some O, Ar, Sn and Pb isotopes are calculated. The values obtained within our approach are very close to those that were calculated within QRPA with the full Skyrme interaction. They are in reasonable agreement with experimental data.Comment: 20 pages, 1 figure, submitted to Phys.Rev.

Unbound exotic nuclei studied by transfer to the continuum reactions

In this paper we show that the theory of transfer reactions from bound to continuum states is well suited to extract structure information from data obtained by performing "spectroscopy in the continuum". The low energy unbound states of nuclei such as $^{10}$Li and $^{5}$He can be analyzed and the neutron-core interaction, necessary to describe the corresponding borromean nuclei $^{11}$Li and $^{6}$He can be determined in a semi-phenomenological way. An application to the study of $^{10}$Li is then discussed and it is shown that the scattering length for s-states at threshold can be obtained from the ratio of experimental and theoretical cross sections. The scattering single particle states of the system n+$^{9}$Li are obtained in a potential model. The corresponding S-matrix is used to calculate the transfer cross section as a function of the neutron continuum energy with respect to $^{9}$Li. Three different reactions are calculated $^{9}Li(d,p)^{10}Li$, $^{9}Li(^{9}Be,^{8}Be)^{10}Li$, $^{9}Li(^{13}C,^{12}C)^{10}Li$, to check the sensitivity of the results to the target used and in particular to the transfer matching conditions. Thus the sensitivity of the structure information extracted from experimental data on the reaction mechanism is assessed.Comment: 21 pages, 5 ps figures, accepted for publication on Nucl. Phys.

Structure of isobaric analog states in 91Nb populated by the 90Zr(a,t) reaction

Decay via proton emission of isobaric analog states (IAS's) in $^{91}{Nb}$ was studied using the $^{90}{Zr}(\alpha,t)$ reaction at $E_\alpha$=180 MeV. This study provides information about the damping mechanism of these states. Decay to the ground state and low-lying phonon states in $^{90}{Zr}$ was observed. The experimental data are compared with theoretical predictions wherein the IAS `single-particle' proton escape widths are calculated in a continuum RPA approach. The branching ratios for decay to the phonon states are explained using a simple model.Comment: 3 figures. submitted to Phys. Lett.

The decline and rise of neighbourhoods: the importance of neighbourhood governance

There is a substantial literature on the explanation of neighbourhood change. Most of this literature concentrates on identifying factors and developments behind processes of decline. This paper reviews the literature, focusing on the identification of patterns of neighbourhood change, and argues that the concept of neighbourhood governance is a missing link in attempts to explain these patterns. Including neighbourhood governance in the explanations of neighbourhood change and decline will produce better explanatory models and, finally, a better view about what is actually steering neighbourhood change

Single-neutron transfer from 11Be gs via the (p,d) reaction with a radioactive beam

The 11Be(p,d)10Be reaction has been performed in inverse kinematics with a radioactive 11Be beam of E/A = 35.3 MeV. Angular distributions for the 0+ ground state, the 2+, 3.37 MeV state and the multiplet of states around 6 MeV in 10Be were measured at angles up to 16 deg CM by detecting the 10Be in a dispersion-matched spectrometer and the coincident deuterons in a silicon array. Distorted wave and coupled-channels calculations have been performed to investigate the amount of 2+ core excitation in 11Be gs. The use of "realistic" 11Be wave functions is emphasised and bound state form factors have been obtained by solving the particle-vibration coupling equations. This calculation gives a dominant 2s component in the 11Be gs wave function with a 16% [2+ x 1d] core excitation admixture. Cross sections calculated with these form factors are in good agreement with the present data. The Separation Energy prescription for the bound state wave function also gives satisfactory fits to the data, but leads to a significantly larger [2 x 1d] component in 11Be gs.Comment: 39 pages, 12 figures. Accepted for publication in Nuclear Physics A. Added minor corrections made in proof to pages 26 and 3

Logics, thresholds, strategic power, and the promotion of liberalisation by governments: a case study from British Higher Education

Liberalisation has become an increasingly important policy trend, both in the private and public sectors of advanced industrial economies. This article eschews deterministic accounts of liberalisation by considering why government attempts to institute competition may be successful in some cases and not others. It considers the relative strength of explanations focusing on the institutional context, and on the volume and power of sectoral actors supporting liberalisation. These approaches are applied to two attempts to liberalise, one successful and one unsuccessful, within one sector in one nation – higher education in Britain. Each explanation is seen to have some explanatory power, but none is sufficient to explain why competition was generalised in the one case and not the other. The article counsels the need for scholars of liberalisation to be open to multiple explanations which may require the marshalling of multiple sources and types of evidence