Isovector soft dipole mode in 6Be

By using the 1H(6Li,6Be)n charge-exchange reaction, continuum states in 6Be were populated up to E_t=16 MeV, E_t being the 6Be energy above its three-body decay threshold. In kinematically complete measurements performed by detecting alpha+p+p coincidences, an E_t spectrum of high statistics was obtained, containing approximately ~5x10^6 events. The spectrum provides detailed correlation information about the well-known 0^+ ground state of 6Be at E_t=1.37 MeV and its 2^+ state at E_t=3.05 MeV. Moreover, a broad structure extending from 4 to 16 MeV was observed. It contains negative parity states populated by Delta L=1 angular momentum transfer without other significant contributions. This structure can be interpreted as a novel phenomenon, i.e. the isovector soft dipole mode associated with the 6Li ground state. The population of this mode in the charge-exchange reaction is a dominant phenomenon for this reaction, being responsible for about 60% of the cross section obtained in the measured energy range.Comment: 8 pages, 7 figure

Sub-barrier fusion of 6

Cross-sections for the production of 210Po nuclei in 6He + 206Pb collisions over the incident energy range 14-18 MeV were measured by means of the activation technique and a radiochemical analysis. The elastic scattering at 18.0 MeV was also measured providing a precise value for the 210Po production cross-section at this energy. The results are at variance with the earlier experimental data and rather in accord with the predictions of a density-dependent barrier penetration model for the fusion process. A proper treatment of beam energy distribution for the evaluation of the activation data is discussed. © Società Italiana di Fisica/Springer-Verlag 2011

Breakup and neutron-transfer effects on 6He+206Pb elastic scattering below the Coulomb barrier

The elastic scattering and inclusive α-particle yield for the 6He+206Pb system at an incident energy of 18 MeV, just below the nominal Coulomb barrier, have been measured. The α-particle yield at forward angles is also reported. The data are analyzed by means of continuum-discretized coupled-channels, distorted wave Born approximation, and coupled reaction channels calculations. Couplings to the one-neutron- and two-neutron-transfer reactions are found to be able to account for most of the absorption in the entrance channel. © 2013 American Physical Society

Detailed Study of External Correlations in the Low-Energy Spectrum of Beryllium-6

Three-body continuum p-p-α for the charge exchange reaction 1H(6Li,6Be)n is studied in detail. The data are obtained with a high volume of statistics (approximately 4.7 million events), making it possible to analyze three-particle correlations. Detailed information about the structure of 6Ве and the reaction is obtained as a result

Status of the ACCULINNA-2 project at FLNR

The project of a new and more powerful in-flight fragment separator ACCULINNA-2 at U-400M cyclotron in FLNR, JINR planned to build in addition to the existing separator ACCULINNA is presented. The new separator will provide high intensity RIBs in the lowest energy range (5\uf750 MeV/nucleon) which is attainable for in-flight separators. The possibilities for the astrophysics studies at the proposed device are presented. ACCULINNA-2 separator is planned to be constructed in the years 2010-2015. The current status of the project is reported

Precise measurement of near-barrier 8^{8}He+208^{208}Pb elastic scattering: Comparison with 6^{6}He

Expérience GANILInternational audienceDramatic differences in the elastic scattering of the neutron rich nuclei 6He and 8He are found when new highquality data for the 8He+208Pb system are compared with previously published 6He+208Pb data at the samelaboratory frame incident energy. The new 8He data are of the same level of detail as for stable beams. Whencomparing them with those previously obtained for 6He+208Pb at the same energy, it is possible to determinefrom the data alone that 6He has a much longer range absorption than 8He. However, both nuclei show significantabsorption beyond their strong absorption radii. While it has been known for a long time that elastic scattering atenergies around the barrier only determines the optical potential over a small distance in radial space, typically±0.5 fm or so, both the 6He and the 8He imaginary potentials obtained from various optical model fits to thesedata are the same over a much wider range of ±1.5 fm

Interaction of 8^{8}He with 208^{208}Pb at near-barrier energies: 4^{4}He and 6^{6}He production

International audienceAngular distributions for the inclusive He4 and He6 production cross sections in the He8+Pb208 system at incident energies of 16 and 22 MeV measured at the SPIRAL facility of the GANIL laboratory are presented. Using a combination of kinematical arguments and distorted wave Born approximation (DWBA) calculations, neutron transfer reactions were inferred to be the dominant contributors to both inclusive cross sections. Model-dependent values for the ratios of two- to one-neutron stripping, σ2n/σ1n, were derived and compared with previous results for He8 and He6 projectiles incident on other heavy targets. Three- and four-neutron stripping were inferred to be the main processes leading to He4 production, although the exact mechanism remains to be elucidated