Two-phonon giant resonances in136Xe,208Pb,and

Abstract

The excitation of the double-phonon giant dipole resonance was observed in heavy projectile nuclei impinging on targets of high nuclear charge with energies of 500-700 MeV/nucleon. New experimental data are presented for 136 Xe and 238 U together with further analysis of earlier data on 208 Pb. Differential cross sections d/dE* and d/d for electromagnetic excitations were deduced. Depending on the isotope, cross sections appear to be enhanced in comparison to those expected from a purely harmonic nuclear dipole response. The cumulative effect of excitations of two-phonon states composed of one dipole and one quadrupole phonon, of predicted anharmonicities in the double-phonon dipole response, and of damping of the dipole resonance during the collision may account for the discrepancy. In addition, decay properties of two-phonon resonances were studied and compared to that of a statistical decay.

Coulomb dissociation ofN20,21

“…Each paddle (10 cm thick) consists of consecutively 5 mm iron converter (to convert the neutrons into detectable charged particles) and 5 mm plastic scintillator sheets. Further details can be found elsewhere [16,17].…”

“…The total neutron efficiency of LAND is based on a simulation which includes the acceptance due to the kinematics of the specific reaction, the acceptance due to deactivated/broken paddles and the nominal energy-dependent neutron efficiency of the detector measured in an earlier experiment [17].…”

Direct experimental evidence for a multiparticle-hole ground state configuration of deformedMg33

“…The core state, which is coupled with the neutron, can be identified by the characteristic γ rays from the decaying core after the breakup. In order to compare with the experimental results, all the calculated results shown in this article are convoluted with the response function [24,29].…”

Beyond the neutron drip line: The unbound oxygen isotopes25O and26O

“…The simulation is based on measured real 1n events from deuteron breakup reactions. The 2n events are generated by overlaying the shower patterns of secondary particles from these measured 1n events according to the simulated positions on the neutron detector and are then analyzed in the same way as the experimental data [29]. The generated response matrices thus do not rely on a simulation of the reactions in the neutron detection process.…”