Isotopic Dependence of the Nuclear Caloric Curve

The A/Z dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at SIS. A stable beam of 124Sn and radioactive beams of 124La and 107Sn at 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z of the produced spectator sources, consistent with predictions for expanded systems. Small Coulomb effects (\Delta T \approx 0.6 MeV) appear for residue production near the onset of multifragmentation.Comment: 11 pages, 3 figures, accepted for publ. in Phys. Rev. Let

Measurement of the 92,93,94,100Mo(γ,n) reactions by Coulomb Dissociation

The Coulomb Dissociation (CD) cross sections of the stable isotopes 92,94,100Mo and of the unstable isotope 93Mo were measured at the LAND/R3B setup at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Experimental data on these isotopes may help to explain the problem of the underproduction of 92,94Mo and 96,98Ru in the models of p-process nucleosynthesis. The CD cross sections obtained for the stable Mo isotopes are in good agreement with experiments performed with real photons, thus validating the method of Coulomb Dissociation. The result for the reaction 93Mo(γ,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the 94Mo(γ,n) reaction is presented. Further analysis will complete the experimental database for the (γ,n) production chain of the p-isotopes of molybdenum

Beta decay of medium and high spin isomers in "9"4Ag

The very neutron-deficient isotope "9"4Ag was produced at the GSI on-line mass separator by using the reaction "5"8Ni("4"0Ca,p3n). The #beta#-decay properties of "9"4Ag were studied by detecting for the first time #beta#-delayed #gamma# rays and #beta#-#gamma#-#gamma# coincidences. Both the population of excited levels in the daughter nucleus "9"4Pd and the #beta#-decay half-life of "9"4Ag were investigated. The major part of the feeding was assigned to the decay of an I"#pi#=(7"+) isomer with a half-life of (0.36#+-#0.03) s. A weak #beta#-decay branch was found to populate high-spin levels in the "9"4Pd daughter with I#>=#18. It is tentatively assigned to the decay of a high-spin parent state in "9"4Ag with I#>=#17 and a half-life (0.3#+-#0.2) s. The measured #beta#-decay properties as well as the level structure of "9"4Ag and "9"4Pd are discussed in comparison with shell-model predictions. (orig.)SIGLEAvailable from TIB Hannover: RO 801(2002-19) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman