S-matrix studies of resonances in A=3,4,5,6, and 12 nucleon systems

Resonances of certain light nuclei are explored by studying the complex pole structures of the scattering matrices. Among other results we predict the existence of three-neutron and three-proton resonances, a small spin-orbit splitting in the low-lying He-5 and Li-5 states and the nonexistence of the soft dipole resonance in He-6.Comment: Talk given at the XVth International Conference on Few-Body Problems in Physics (22-26 July, 1997, Groningen, The Netherlands). To be published in the conference proceedings in Nucl. Phys. A. 5 pages with 2 figures. The postscript file and more information are available at http://qmc.lanl.gov/~csot

Effects of B-8 size on the low-energy Be7(p,gamma)B8 cross section

We calculate several "size-like" B-8 observables within the microscopic three-cluster model and study their potential constraints on the zero-energy astrophysical S_{17}(0) factor of the Be7(p,gamma)B8 reaction. We find within our three-cluster model that a simultaneous reproduction of the experimental data for the B-8 radius and quadrupole moment and of the B8-Li8 Coulomb displacement energy implies S_{17}(0)=(23-25) eVb.Comment: 8 pages with 1 figure. The original version with further details and more information are available at http://qmc.lanl.gov/~csot

Low-lying continuum structures in B8 and Li8 in a microscopic model

We search for low-lying resonances in the B8 and Li8 nuclei using a microscopic cluster model and a variational scattering method, which is analytically continued to complex energies. After fine-tuning the nucleon-nucleon interaction to get the known 1+ state of B8 at the right energy, we reproduce the known spectra of the studied nuclei. In addition, our model predicts a 1+ state at 1.3 MeV in B8, relative to the Be7+p threshold, whose corresponding pair is situated right at the Li7+n threshold in Li8. Lacking any experimental evidence for the existence of such states, it is presently uncertain whether these structures really exist or they are spurious resonances in our model. We demonstrate that the predicted state in B8, if it exists, would have important consequences for the understanding of the astrophysically important Be7(p,gamma)B8 reaction.Comment: 6 pages with 1 figure. The postscript file and more information are available at http://nova.elte.hu/~csot

Information technology in rural Hungary: plans and reality

Rural areas cover 87% of the territory and are inhabited by 45% of the population in Hungary. These areas have the same problem as most of the rural areas in Europe: migration of the active, well-trained labour force, depopulation, unfavourable age structure, high unemployment rate with critical labour market situation in the small settlements. Information and Communication Technology – if used properly – can serve as a solution to these problems, although there is much to be done in this field. The authors have started to examine the current situation of the basic ICT-indicators in Hungary, with a special focus on small settlements, and they have also given a historical overview on the past years’ governmental strategies (especially the National Information Society Strategy), the new National Rural Development Strategy and civic efforts (ex. The telecottage movement) to boost the widespread usage of these technologies, as well as an evaluation of the impact of the aforementioned factors

Large-space cluster model calculations for the He3(He3,2p)He4 and H3(H3,2n)He4 reactions

The He3(He3,2p)He4 and H3(H3,2n)He4 reactions are studied in a microscopic cluster model. We search for resonances in the He3+He3 and He4+p+p channels using methods that treat the two- and three-body resonance asymptotics correctly. Our results show that the existence of a low-energy resonance or virtual state, which could influence the Be-7 and B-8 solar neutrino fluxes, is rather unlikely. Our calculated He3(He3,2p)He4 and H3(H3,2n)He4 cross sections are in a good general agreement with the experimental data.Comment: 12 pages with 3 figures. The postscript file and more information are available at http://nova.elte.hu/~csot

Pairing anti-halo effect

We discuss pairing correlations in weakly bound neutron rich nuclei, by using the coordinate-space Hartree-Fock-Bogolyubov approach which allows to take properly into account the coupling to particle continuum. We show that the additional pairing binding energy acts against a development of an infinite rms radius, even in situations when an l=0 single-particle orbital becomes unbound.Comment: 10 RevTeX pages, 3 EPS figure

Parity-violating alpha-decay of the 3.56-MeV J,T=0+,1 state of Li-6

We study the parity-violating alpha+d decay of the lowest 0+ state of Li-6 in a microscopic three-cluster model. The initial bound and the final scattering states are described consistently within the same model. The parity-violating decay width is calculated in perturbation theory using the parity-nonconserving nucleon-nucleon interaction of Desplanques, Donoghue, and Holstein (DDH). We find that the decay width is sensitive to dynamical degrees of freedom which are beyond the alpha+p+n model, for example, alpha excitation and breakup. In our full model, which contains breathing excitations of the alpha particle and H-3 + He-3 rearrangement, the parity-nonconserving decay width is Gamma=3.97x10^{-9} eV, using the DDH coupling constants.Comment: LaTex with RevTe