Alinka Lepine-Szily

Bio: Alinka Lepine-Szily is an academic researcher from University of São Paulo. The author has contributed to research in topics: Elastic scattering & Scattering. The author has an hindex of 16, co-authored 109 publications receiving 964 citations. Previous affiliations of Alinka Lepine-Szily include Katholieke Universiteit Leuven.

No enhancement of fusion probability by the neutron halo of 6He

Abstract: Quantum tunnelling through a potential barrier ( such as occurs in nuclear fusion) is very sensitive to the detailed structure of the system and its intrinsic degrees of freedom(1,2). A strong increase of the fusion probability has been observed for heavy deformed nuclei(3). In light exotic nuclei such as He-6, Li-11 and Be-11 ( termed 'halo' nuclei(4)), the neutron matter extends much further than the usual nuclear interaction scale. However, understanding the effect of the neutron halo on fusion has been controversial - it could induce a large enhancement of fusion(5), but alternatively the weak binding energy of the nuclei could inhibit the process(6). Other reaction channels known as direct processes ( usually negligible for ordinary nuclei) are also important: for example, a fragment of the halo nucleus could transfer to the target nucleus through a diminished potential barrier. Here we study the reactions of the halo nucleus He-6 with a U-238 target, at energies near the fusion barrier. Most of these reactions lead to fission of the system, which we use as an experimental signature to identify the contribution of the fusion and transfer channels to the total cross-section. At energies below the fusion barrier, we find no evidence for a substantial enhancement of fusion. Rather, the ( large) fission yield is due to a two-neutron transfer reaction, with other direct processes possibly also involved.

Mass Measurement of 100Sn.

Abstract: Secondary ions of ${}^{100}$Ag, ${}^{100}$Cd, ${}^{100}$In, and ${}^{100}$Sn were produced via the fusion-evaporation reaction ${}^{50}\mathrm{Cr}{+}^{58}\mathrm{Ni}$ at an energy of 51 MeV/nucleon, and were accelerated simultaneously in the second cyclotron of GANIL. About 10 counts were observed from the production and acceleration of ${}^{100}\mathrm{Sn}{}^{22+}$. The masses of ${}^{100}$Cd, ${}^{100}$In, and ${}^{100}$Sn were measured with respect to ${}^{100}$Ag using the GANIL cyclotron, with precisions of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, and ${10}^{\ensuremath{-}5}$, respectively.

Experimental determination of the surface density for the 6 He exotic nucleus

Abstract: Angular distributions for the elastic scattering of ${}^{4,6}\mathrm{He}$ on ${}^{58}\mathrm{Ni}$ have been measured at near-barrier energies. The present data, combined with others for the ${}^{4}\mathrm{He}{+}^{58}\mathrm{Ni}$ system at intermediate energies, allowed the determination of the ${}^{4,6}\mathrm{He}$ ground-state nuclear densities through an unfolding method. The experimentally extracted nuclear densities are compared with the results of theoretical calculations.

The Radioactive Ion Beams in Brazil (RIBRAS) facility Description, program, main results, future plans

Abstract: RIBRAS (Radioactive Ion Beams in Brazil) is a facility installed at the Institute of Physics of the University of Sao Paulo (IFUSP), Brazil. The RIBRAS system consists of two superconducting solenoids and uses the “in-flight method” to produce radioactive ion beams using the primary beam provided by the 8UD Pelletron Tandem of IFUSP. The ion beams produced so far by RIBRAS are 6He, 8Li, 7Be, 10Be, 8B, 12B with intensities that can vary from 104 to 106 pps. Initially the experimental program covered the study of elastic and inelastic scattering with the objective to study the interaction potential and the reaction mechanisms between weakly bound (RIB) and halo (6He and 8B projectiles on light, medium and heavy mass targets. With highly purified beams, the study of resonant elastic scattering and resonant transfer reactions, using inverse kinematics and thick targets, has also been included in our experimental program. Also, transfer reactions of astrophysical interest and fusion reactions induced by halo nuclei are part of the near-future research program. Our recent results on elastic scattering, alpha-particle production and total reaction cross sections, as well as the resonant elastic and transfer reactions, are presented. Our plans for the near future are related to the installation of a new beam line and a cave for gamma-ray detection. We intend to place in operation a large area neutron detector available in our laboratory. The long-range plans could be the move of the RIBRAS system to the more energetic beam line of the LINAC post-accelerator (10MeV/nucleon primary beams) still in construction in our laboratory.

Elongated shape isomers in the Ar36 nucleus

Abstract: A recent analysis of the {sup 12}C+{sup 24}Mg scattering [W. Sciani et al., Phys. Rev. C 80, 034319 (2009)] suggests the existence of a hyperdeformed band in the {sup 36}Ar nucleus, completely in line with the predictions of {alpha}[W. D. M. Rae and A. C. Merchant, Phys. Lett. B279, 207 (1992)] and binary cluster calculations [J. Cseh et al., Phys. Rev. C 70, 034311 (2004)]. Here we review the structural understanding of the superdeformed and the hyperdeformed states of {sup 36}Ar and present new results on the shape isomers as well. Special attention is paid to the clusterization of these states, which indicates the appropriate reaction channels for their formation.

Transition probability from the ground to the first-excited 2^+ state of even-even nuclides

Abstract: Adopted values for the reduced electric quadrupole transition probability, B(E2)↑, from the ground state to the first-excited 2+ state of even–even nuclides are given in Table I. Values of τ, the mean life of the 2+ state; E, the energy; and β, the quadrupole deformation parameter, are also listed there. The ratio of β to the value expected from the single-particle model is presented. The intrinsic quadrupole moment, Q0, is deduced from the B(E2)↑ value. The product E×B(E2)↑ is expressed as a percentage of the energy-weighted total and isoscalar E2 sum-rule strengths. Table II presents the data on which Table I is based, namely the experimental results for B(E2)↑ values with quoted uncertainties. Information is also given on the quantity measured and the method used. The literature has been covered to November 2000. The adopted B(E2)↑ values are compared in Table III with the values given by systematics and by various theoretical models. Predictions of unmeasured B(E2)↑ values are also given in Table III.