Electromagnetic excitation of the two-phonon giant dipole resonance

The nuclear response of "1"3"6Xe and "2"0"8Pb to electromagnetic excitation was studied in peripheral, near-relativistic heavy-ion collisions. Large cross sections were observed for the one-phonon and two-phonon isovector giant dipole resonance. The results, in particular the unexpectedly large strength found for the double giant dipole resonance, are discussed and compared to that of other recent measurements. (orig.)Available from TIB Hannover: RO 801(93-72) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Electromagnetic excitation of the double giant dipole resonance in "1"3"6Xe

Available from TIB Hannover: RO 801(92-64) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Two-phonon giant dipole resonance in "2"0"8Pb

Excitation of the two-phonon isovector giant dipole resonance was observed in "2"0"8Pb 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 #gamma#-decay probabilities are derived as well. (orig.)SIGLEAvailable from TIB Hannover: RO 801(96-27) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Exclusive studies of neutron and charged particle emission in collisions of "1"9"7Au+"1"9"7Au at 400 MeV/nucleon

We present data on collective flow of neutrons in collisions of "1"9"7Au+"1"9"7Au at 400 MeV/nucleon. The azimuthal distribution about the beam axis is investigated with respect to the reaction plane as determined from light charged particles. The 'squeeze-out' of neutrons, perpendicular to the reaction plane, is observed for the first time. Quantitative agreement to a high level of accuracy is found between the behaviour of neutrons and hydrogen ions. (orig.)Accepted for publication by Phys. Rev. Lett.SIGLEAvailable from TIB Hannover: RO 801(93-60) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Energy dependence of collective flow of neutrons and charged particles in "1"9"7Au+"1"9"7Au collisions

Our contribution focusses on one particular aspect of collective flow of nuclear matter: the so-called ''squeeze-out'', i.e. the preferential emission of mid-rapidity particles perpendicular to the reaction plane. The data were taken for the system "1"9"7Au + "1"9"7Au at 400, 600 and 800 MeV/u. We cover two topics, the comparison of neutrons and protons, and the bombarding energy dependence of the neutrons' squeeze-out. (orig.)Available from TIB Hannover: RO 801(94-02) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Neutron momentum distribution from ''core break-up'' reactions of halo nuclei

Neutron angular distributions from violent break-up reactions of "1"1Li and "1"1Be have been measured at 28 MeV/u and 280 MeV/u and at 41 MeV/u and 460 MeV/u, respectively. The derived neutron momentum distributions show a narrow component in transverse momentum that is within uncertainties independent of beam energy and target charge. This component is suggested to be simply related to the momentum distribution of the loosely bound halo neutron(s) in the projectiles. (orig.)SIGLEAvailable from TIB Hannover: RO 801(95-02) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

"6He and neutron momentum distributions from "8He in nuclear break-up reactions at 240 MeV/u

Neutron and "6He momentum distributions from "8He break-up reactions in a C-target have been measured at 240 MeV/u. The two-neutron removal cross section was found to be #sigma#_-_2_n=0.27#+-#0.03 b. The nature of the momentum distributions is interpreted in some simple reaction scenarios. (orig.)32 refs.SIGLEAvailable from TIB Hannover: RO 801(96-04) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman