K. Boretzky

Two-phonon giant dipole resonance in 208Pb☆

Abstract Excitation of the two-phonon isovector giant dipole resonance was observed in 208Pb projectiles incident on different target nuclei (C, Sn, Ho, Pb, U) at high energy (640 A·MeV). Evidence is found for a two-step electromagnetic excitation mechanism. An enhancement of 1.33(16) for the excitation cross section is observed relative to the harmonic approximation. Neutron- and γ-decay probabilities are derived as well.

Results of the ASY-EOS experiment at GSI : the symmetry energy at suprasaturation density

Directed and elliptic flows of neutrons and light charged particles were measured for the reaction 197Au+197Au at 400 MeV/nucleon incident energy within the ASY-EOS experimental campaign at the GSI laboratory. The detection system consisted of the Large Area Neutron Detector LAND, combined with parts of the CHIMERA multidetector, of the ALADIN Time-of-flight Wall, and of the Washington-University Microball detector. The latter three arrays were used for the event characterization and reaction-plane reconstruction. In addition, an array of triple telescopes, KRATTA, was used for complementary measurements of the isotopic composition and flows of light charged particles. From the comparison of the elliptic flow ratio of neutrons with respect to charged particles with UrQMD predictions, a value \gamma = 0.72 \pm 0.19 is obtained for the power-law coefficient describing the density dependence of the potential part in the parametrization of the symmetry energy. It represents a new and more stringent constraint for the regime of supra-saturation density and confirms, with a considerably smaller uncertainty, the moderately soft to linear density dependence deduced from the earlier FOPI-LAND data. The densities probed are shown to reach beyond twice saturation.

Two-phonon giant resonances in 136 Xe, 208 Pb, and 238 U

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 ds/dE* and ds/du 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.

A LARGE-AREA SCINTILLATING FIBRE DETECTOR FOR RELATIVISTIC HEAVY IONS

Abstract A scintillating fibre detector for relativistic heavy ions with an active area of 50 × 50 cm 2 has been developed and was tested with various ion beams (1 ≤ Z ≤ 92). At count rates of up to 10 5 particles/s, the position resolution was found to be determined by the fibre width of 1 mm; depending on the nuclear charge of the beam, efficiencies between 89% and 100% and time resolutions between 800 and 200 ps (FWHM) were obtained.

First measurement of the 96Ru( p,γ )97Rh cross section for the p process with a storage ring

This work presents a direct measurement of the

Structure of 55Ti from relativistic one-neutron knockout

^{96}

Neutron-skin thickness from the study of the anti-analog giant dipole resonance

Ru(

Performance of timing resistive plate chambers with relativistic neutrons from 300 to 1500 MeV

p, \gamma

Coulomb excitation of exotic nuclei at the R3B-LAND setup

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Neutron recognition in the LAND detector for large neutron multiplicity

^{97}