Probing pre-formed alpha particles in the ground state of nuclei

In this Letter, we report on alpha particle emission through the nuclear break-up in the reaction 40Ca on a 40Ca target at 50A MeV. It is observed that, similarly to nucleons, alpha particles can be emitted to the continuum with very specific angular distribution during the reaction. The alpha particle properties can be understood as resulting from an alpha cluster in the daughter nucleus that is perturbed by the short range nuclear attraction of the collision partner and emitted. A time-dependent theory that describe the alpha particle wave-function evolution is able to reproduce qualitatively the observed angular distribution. This mechanism offers new possibilities to study alpha particle properties in the nuclear medium.Comment: 4 pages, 3 figure

Charge and current-sensitive preamplifiers for pulse shape discrimination techniques with silicon detectors

New charge and current-sensitive preamplifiers coupled to silicon detectors and devoted to studies in nuclear structure and dynamics have been developed and tested. For the first time shapes of current pulses from light charged particles and carbon ions are presented. Capabilities for pulse shape discrimination techniques are demonstrated.Comment: 14 pages, 12 figures, to be published in Nucl. Inst. Meth.

Probing the 6He halo structure with elastic and inelastic proton scattering

Proton elastic scattering and inelastic scattering to the first excited state of 6He have been measured over a wide angular range using a 40.9A MeV 6He beam. The data have been analyzed with a fully microscopic model of proton-nucleus scattering using 6He wave functions generated from large space shell model calculations. The inelastic scattering data show a remarkable sensitivity to the halo structure of 6He.Comment: 9 pages, 3 figures. RevTeX. Replaced figure 3 with updated figur

1n- and 2n-transfer with the Borromean nucleus 6^{6}He near the Coulomb barrier

Accepetd for publication in Physical Review LettersAngular distributions for 1n- and 2n-transfer are reported for the 6He + 65Cu system at Elab = 22.6 MeV. For the first time, triple coincidences between particles, neutrons and characteristic rays from the target-like residues were used to separate the contributions arising from 1n- and 2n-transfer. The differential cross sections for these channels, elastic scattering, and fusion were analyzed using a Coupled Reaction Channels approach. The large measured ratio of the 2n/1n cross section and the strong influence of 2n-transfer on other channels indicate that the di-neutron configuration of 6He plays a dominant role in the reaction mechanism

Inverse kinematics proton scattering from the exotic nucleus 22^{22}O

NESTER PTHInternational audienceWe have measured for the first time elastic and inelastic proton scattering from the neutron rich nucleus 22O at 46.6 AMeV using the MUST array

Structure of exotic nuclei from direct reactions

Expérience GANILInternational audienc