Search for states with enlarged radii in excited states of 12B

An experiment was done to search for states with a neutron halo in 12B. The measurements were carried out at the cyclotron of the University of Jyvaskyla (Finland) using Large Scattering Chamber (LSC). The idea of the work was to search for two states with the expected neutron halo, 1 ̄ and 2 ̄. Differential cross sections with excitation of 12B states, including abovementioned states, were observed. The preliminary calculations on halo radii by the method of asymptotic normalization coefficients for the 2 ̄ and 1 ̄ states which are in a discrete spectrum gave following values: 5.6 fm and 7.4 fm, which is much larger than the radius of the valence neutron in the ground state. But strictly the presence of a neutron halo can be confirmed only for 1 ̄ state. The 2 ̄ state can be considered only as candidate for halo. An unexpected result was obtained for the 3 ̄, 3.39 MeV state, which is in continuum 19 keV above the decay threshold 12B → 11B + n, preliminary estimation for its halo radius is ∼ 6.5 fm. This indicates that the halo can be present in this state as well. But strict conditions for neutron halo are not fulfilled in the same way as for 2 ̄ state. Until now, the neutron halo in unbound states has been observed only for the members of the rotational bands

Examination of the astrophysical S-factors of the radiative proton capture on 2H, 6Li, 7Li, 12C and 13C

Astrophysical S-factors of radiative capture reactions on light nuclei have been calculated in a two-cluster potential model, taking into account the separation of orbital states by the use of Young schemes. The local two-body potentials describing the interaction of the clusters were determined by fitting scattering data and properties of bound states. The many-body character of the problem is approximatively accounted for by Pauli forbidden states. An important feature of the approach is the consideration of the dependence of the interaction potential between the clusters on the orbital Young schemes, which determine the permutation symmetry of the nucleon system. Proton capture on 2H, 6Li, 7Li, 12C, and 13C was analyzed in this approach. Experimental data at low energies were described reasonably well when the phase shifts for cluster-cluster scattering, extracted from precise data, were used. This shows that decreasing the experimental error on differential elastic scattering cross sections of light nuclei at astrophysical energies is very important also to allow a more accurate phase shift analysis. A future increase in precision will allow more definite conclusions regarding the reaction mechanisms and astrophysical conditions of thermonuclear reactions.Comment: 40p., 9 fig., 83 ref. arXiv admin note: substantial text overlap with arXiv:1005.1794, arXiv:1112.1760, arXiv:1005.198

Memoires pour servir a l'Histoire Ecclesiastique des Six Premiers Siecles : Tome Huitieme, qui contient les Vies de S. Athanase, & des Saints qui sont morts depuis l'an 378 jusques en 394, & les histoires des Priscillianistes & des Messaliens

Section IV. Nuclear Reactions Theor

Calculation of (p,γ) and (p,α) nuclear reaction cross sections in stars up to 10 MeV

In Knowledge of the proton-proton (p-p) chain and CNO cycle are required for the evolution of main sequence stars during the early formation of the universe. In this study, we summarized the excitation functions of (p,γ) and (p,α) reactions for 7Be(p,γ)8B, 12C(p,γ)13N, 13C(p,γ)14N, 14N(p,γ)15O and 15N(p,α)15O in p-p chain and CNO cycle using EMPIRE and TALYS computer up to 10 MeV. The calculated data on nuclear fusion cross sections in hydrogen-burning stars were compared with theoretical TENDL-2014 and ENDF/B-VII data from EXFOR. The calculation results show closed agreement between the calculations and the data from literature