D. Beaumel

Determination of the astrophysical S factor of the 8B(p,γ)9C capture reaction from the d(8B,9C)n reaction

The asymptotic normalization coefficients for the virtual decay 9 C → 8 B + p have been determined by measuring the crosssection of the 8 B(d, n) 9 C reaction in inverse kinematics at 14.4 MeV/u, using the RIPS facility. The deduced astrophysical S factor S18 of the 8 B(p ,γ ) 9 C capture reaction in the center of mass energy range 1–100 keV is S18 = 45 ± 13 eV b. uf6d9 2001

Excitation of giant resonances in heavy-ion reactions at intermediate energies: Results from the 40Ar + 90Zr and 208Pb experiments at 41 MeVu☆☆☆

Abstract Giant resonances in 90 Zr and 208 Pb have been studied by inelastic scattering of 40 Ar at 41 MeV/u. Strength distributions and exhausted sum-rule values of different multipolarities are presented. The peak-to-background ratios and differential cross sections from inelastic scattering of heavy ions are compared to those obtained with light projectiles. The influence of Coulomb interaction on the excitation of giant resonances and the possibility to study high multipole resonances by intermediate-energy heavy ions are discussed.

Excitation of giant resonances in 20Ne + 90Zr and 208Pb inelastic scattering at 40 MeV/u☆

The giant resonance region in the inelastic spectra from the reactions 20Ne + 90Zr and 20Ne + 208Pb at 40 MeV/nucleon has been studied with good energy and angular resolutions. The strength distributions of the different multipolarities contributing to the cross section were obtained without making any hypothesis on the excitation energies and shapes of the resonances. In the case of 208Pb the GDR strength was found to be strongly shifted towards lower excitation energies which can be explained by the exponentially decreasing Coulomb excitation probability. Furthermore, indications for a high multipolarity component in the resonance structure were found in both reactions.

Anharmonicity in extended RPA

Abstract We present an anlytical formula for the calculation of the anharmonicity of the two-phonon states which is based on a variational derivation of RPA-like equations for a many-fermion system. Analytical estimations of the anharmonicity have been made using the Lipkin model and a degenerated schematic model. The formula obtained, together with the extended RPA predictions, has been checked by comparison with the exact solutions of the models. A rough estimate of the anharmonicity of the two-phonon state built on the Giant Dipole Resonance and on the Giant Quadrupole Resonance has been deduced.

A new phenomenon in heavy ion inelastic scattering: the towing mode

The inelastic scattering of Ar-40 on Ni-58 has been studied at 44 MeV per nucleon incident energy in coincidence with light particle emission. Besides the well known mechanisms of inelastic excitation, pick up break up and nucleon knock out, a new phenomenon has been observed, giving rise to fast forward moving particles with specific angular correlations. This newly observed mechanism seems to be a generic phenomenon present for various projectile-target combinations and incident energies. Its contribution to the inelastic spectrum has been extracted and a tentative interpretation is given

Probing preformedαparticles in the ground state of nuclei

In this Rapid Communication, we report on {alpha}-particle emission through the nuclear breakup in the reaction {sup 40}Ca on a {sup 40}Ca target at 50 A MeV. It is observed that, similar to nucleons, {alpha} particles can be emitted to the continuum with very specific angular distribution during the reaction. The {alpha}-particle properties seem to be compatible with an {alpha} cluster in the daughter nucleus that is perturbed and is emitted by the short-range nuclear attraction of the collision partner. A time-dependent theory that describes the {alpha}-particle wave-function evolution is able to qualitatively reproduce the observed angular distribution. This mechanism offers new possibilities for studying {alpha}-particle properties in the nuclear medium.

Structure of light exotic nuclei 6,8He and 10,11C from (p,p′) reactions

Abstract The structure of the light unstable nuclei 10,11 C and 6,8 He is investigated by means of (p,p′) reactions. The experiments were performed at GANIL using the MUST detector, an array of Si and SiLi telescopes. The (p,p′) are analyzed within the framework of the microscopic JLM potential, allowing to test the densities predicted by structure models. Preliminary data from the 8 He(p,o′) reaction performed at the SPIRAL facility at 15.6 MeV/nucleon are discussed.

Neutron decay of the isobaric analog state in 208Bi

The isospin-forbidden neutron decay of the isobaric analog state in 208Bi has been measured, following its excitation via the 208Pb(3He, t)“*Bi reaction at 61.2 MeV. In contrast to the proton decay, which is direct, the neutron decay spectrum has a statistical shape. Its branching ratio is determined to be (37 f 3)%. The results suggest that the damping of the isospin impurity is fast. Therefore, neutron decay results mostly from the final stage of the damping process and does not contribute to the width of the IAS.

Measurement of the isoscalar monopole response in the neutron-rich nucleus 68Ni using the active target MAYA

We report the measurement of the isoscalar monopole strength in the unstable nucleus 68Ni using inelastic alpha scattering at 50Au2005MeV in inverse kinematics. This experiment has been performed at GANIL with LISE spectrometer using a dedicated detector: the active target MAYA. A part of the isoscalar giant monopole resonance (ISGMR) has been measured at 21.1 ± 1.9u2005MeV and indications for a soft monopole mode are provided for the first time at 12.9 ± 1.0u2005MeV. Distorted-wave born approximation (DWBA) with random-phase approximation (RPA) transition densities have been used to study angular distribution and indicate that the L = 0 multipolarity dominates the cross-section for the ISGMR, and significantly contributes to the soft mode. ©2015 The Physical Society of Japan

The (t,3He) reaction at 43 MeV/nucleon on 48Ca and 58Ni : Results and microscopic interpretation

We have used the 43 MeV/nucleon primary tritium beam of the AGOR facility with an intensity of 4x10(7) pps and the BBS experimental setup to study the (t,He-3) reaction between 0 degrees and 5 degrees lab angles on C-12, Ca-48, and Ni-58 targets. The standard ray-tracing procedure has allowed us to obtain excitation-energy spectra up to 30 MeV in six angular bins for each residual nucleus, with an average energy resolution of 350 keV. The reaction mechanism has been described in distorted-waves Born approximation (DWBA) using the DWBA98 code. In this approximation, the form factor is treated as a folding of an effective projectile-nucleon interaction with a transition density. The effective projectile-nucleon interaction has been adjusted to reproduce the 0(degrees) cross section of the 1(+) ground state of B-12 populated in the C-12(t,He-3) reaction. We have employed random-phase approximation (RPA) wave functions of excited states to construct the form factor instead of the normal modes wave functions used earlier. This new DWBA+RPA analysis is used to compare calculated and experimental cross sections directly and to discuss the giant resonance excitations in K-48 and Co-58 nuclei.