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New decay data for the isotopes 259Sg and 255Rf were obtained at the velocity filter SHIP using an a-decay spectroscopy measurement. Both isotopes were produced and studied via a one neutron evaporation channel in the compound fusion reaction 54Cr+208Pb. New isomeric states were observed and the single-particle level systematics for isotones with 151 and 153 neutrons were extended. A change of the ground-state configuration for the heaviest N = 151 isotones was observed. Detailed Monte-Carlo simulation for the a decay of 259Sg applying the GEANT4 toolkit was performed and compared with experimental data. [ABSTRACT FROM AUTHOR]

Fission fragment mass distributions were measured in the heavy-ion induced fission using 238U target nucleus. The mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and qasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model in the reactions of 30Si+238U and 34S+238U using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections of 263,264Sg and 267,268Hs, produced by 30Si+238U and 34S+238U, respectively. It is also suggested that the sub-barrier energies can be used for heavy element synthesis. [ABSTRACT FROM AUTHOR]

Advanced nuclear structure models predict the presence of the shell closures N = 14, 16 in neutron-rich O isotopes rather than N = 20. Spectroscopic investigations performed at the neutron drip line have recently confirmed such predictions showing that the 24O is a doubly magic nucleus (Z = 8, N = 16). Predictions within the shell model calculation for the 23,24O ground state have been confirmed measuring their spectroscopic factors. Results obtained in one-neutron removal reactions performed by using in-flight radioactive ion beams produced at the Fragment Separator FRS of GSI are reported. [ABSTRACT FROM AUTHOR]

The production of 283112 in 48Ca induced nuclear reactions was investigated using physical and chemical separation techniques. In the reaction 48Ca on 238U, four events were registered at the SHIP velocity filter. The mean atomic mass of the evaporation residues (EVR) [ABSTRACT FROM AUTHOR]

An overview of present experimental investigation of superheavy elements is given. The data are compared with theoretical descriptions. Results are reported from an experiment to confirm production of element 112 isotopes in irradiation of 238UF4 with 48Ca. One spontaneous fission event was measured, which agrees with three events of previously measured data which had been assigned to the decay of 283112. However, more experimental work is needed in order to obtain an independent and unambiguous confirmation of previous results. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The reaction 30Si + 238U → 268Sg* was studied at beam energies close to the Coulomb barrier. At the above barrier energy of Ec.m. = 144.0 MeV (center-of-mass energy at half thickness of the target), we measured three decay chains of 263Sg produced by evaporation of five neutrons. The cross-section was (67-37+67) pb. At subbarrier energy of Ec.m. = 133.0 MeV we measured three spontaneously fissioning nuclei which we assigned to the isotope 264Sg. The half-life of (120-44+126) ms was determined. The production cross-section was (10-6+10) pb, which is about four orders magnitude larger than the calculation based on the one-dimensional barrier penetration model in the fusion process, showing fusion enhancement caused by the prolate deformation of 238U. At Ec.m. = 128.0 MeV an upper cross-section limit of 15 pb was measured. Compared to excitation functions measured for the lighter system 16O + 238U → 254Fm*, a reduction of the fusion probability was observed at low beam energies indicating increasing competition from quasifission processes. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The use of metallic lead or bismuth targets is limited at high beam currents due to their low melting point. In order to increase the intensity for irradiation, we investigated chemical compound targets with higher melting temperature. The properties of these targets are promising for further increase of the sensitivity in experiments searching for superheavy elements. The target material is controlled in each step of the production process as well as after the irradiation by optical microscopy, weighing, scanning electron microscopy (SEM), and energy-dispersive x-ray analysis (EDX). In some cases also wavelength dispersive x-ray analysis (WDX), and Atomic Force Microscopy (AFM) are applied. We report on the synthesis of the target material, the production of the targets and their application in heavy-ion experiments. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report on the status of target development for the heavy-element program at GSI, namely for the SHIP experiment. We present some recent results in enhancing the durability of the targets irradiated with the more and more intense heavy-ion beams. The enhancement of the beam intensity is necessary in order to keep beam times at reasonable length despite cross sections in the picobarn region. We synthesised new compound targets on [sup 208]Pb -basis with significantly higher melting temperatures and built up a target monitoring system. To investigate the high-current targets and develop an active cooling system we built up a test bench for offline experiments. [ABSTRACT FROM AUTHOR]