[en] The secondary-beam facility of GSI Darmstadt was used to study the fission properties of 70 short-lived radioactive nuclei. Most of them have not been accessible so far in conventional fission experiments. Relativistic secondary projectiles were produced by fragmentation of a 1 A GeV ²³⁸U primary beam and identified in nuclear charge and mass number. Using these reaction products as secondary beams, the giant resonances, mostly the giant dipole resonance, were excited by electromagnetic interactions in a secondary lead target, and fission from excitation energies around 11 MeV was induced. The fission fragments were identified in nuclear charge, and their velocity vectors were determined. Elemental yields and total kinetic energies have been obtained for a number of neutron-deficient actinides and pre-actinides. The characteristics of multimodal fission of nuclei around ²⁷⁷Th were systematically investigated. The proton even-odd effect was determined for all systems. (orig.)

[en] Advances in micro-technology demand that new functional materials be developed so that the technical properties of micro-devices can be improved at reasonable cost. The co-deposition of nanoscaled particles during an electroplating process has been shown to bring such an improvement. This work focuses on particles of oxidic ceramics, in this case those of Al₂O₃ and TiO₂. The diameters of the primary particles ranges from 10 to 30 nm, electrodeposited by means of a conventional Watts nickel electrolyte. A series of nickel nano-ceramic composites were produced, with co-deposition of particles as a single primary particle in the nanometre range at one end of the scale and as agglomerates up to a size of a micrometer at the other. The influence of the presence of particles on crystallisation behaviour, residual stress and texture of the deposited nickel coatings was examined by X-ray diffraction (XRD). There is a report on the interfaces between the nickel grains and the oxidic ceramic particles, investigated using transmission electron microscopy (TEM). A decreasing corrosion stability indicates an attack along the interface nickel/particles

[en] A global view on the properties of fission channels is presented. Surprisingly, the positions of the two asymmetric fission channels are found to be constant in atomic number over the whole range of systems investigated. (author)

[en] The secondary-beam facility of GSI Darmstadt was used to study the fission properties of 70 short-lived radioactive nuclei. Most of them have not been accessible so far in conventional fission experiments. Relativistic secondary projectiles were produced by fragmentation of a 1 A GeV ²³⁸U primary beam and identified in nuclear charge and mass number. Using these reaction products as secondary beams, the giant resonances, mostly the giant dipole resonance, were excited by electromagnetic interactions in a secondary lead target, and fission from excitation energies around 11 MeV was induced. The fission fragments were identified in nuclear charge, and their velocity vectors were determined. Elemental yields and total kinetic energies have been obtained for a number of neutron-deficient actinides and preactinides. The characteristics of multimodal fission of nuclei around ²²⁷Th were systematically investigated. The proton even-odd effect was determined for all systems

[en] Isotopic series of 58 neutron-deficient secondary projectiles (^205,206At, ^205-209Rn, ^{208-212,217,218}Fr, ^211-223Ra, ^215-226Ac, ^221-229Th, ^226-231Pa, ^231-234U) were produced by projectile fragmentation using a 1 A GeV ²³⁸U beam. Cross sections of fission induced by nuclear and electromagnetic interactions in a secondary lead target were measured. They were found to vary smoothly as a function of proton and neutron number of the fissioning system, also for nuclei with large ground-state shell effects near the 126-neutron shell. No stabilization against fission was observed for these nuclei at low excitation energies. Consequences for the expectations on the production cross sections of super-heavy nuclei are discussed. (orig.)

[en] Isotopic series of 58 neutron-deficient secondary projectiles (^205,206At, ^205-209Rn, ^{208-212,217,218}Fr, ^211-223Ra, ^215-226Ac, ^221-229Th, ^226-231Pa, ^231-234U) were produced by projectile fragmentation using a 1 A GeV ²³⁸U beam. Cross sections of fission induced by nuclear and electromagnetic interactions in a secondary lead target were measured. They were found to vary smoothly as a function of proton and neutron number of the fissioning system, also for nuclei with large ground-state shell effects near the 126-neutron shell. No stabilization against fission was observed for these nuclei at low excitation energies. Consequences for the expectations on the production cross sections of super-heavy nuclei are discussed

[en] Nuclear fission from excitation energies around 11 MeV was studied at GSI, Darmstadt for 76 neutron-deficient actinides and pre-actinides by use of relativistic secondary beams. The characteristics of multimodal fission of nuclei around ²²⁶Th are systematically investigated and related to the influence of shell effects on the potential-energy and on the level density between saddle point and scission. A systematic view on the large number of elemental yields measured gave rise to a new interpretation of the enhanced production of even elements in nuclear fission and allowed for a new understanding of pair breaking in fission. (author)

[en] The secondary-beam facility of GSI Darmstadt was used to study the fission process of short-lived radioactive nuclei. Relativistic secondary projectiles were produced by fragmentation of a 1 A GeV ²³⁸U primary beam and identified in nuclear charge and mass number. Their production cross sections were determined, and the fission competition in the statistical deexcitation was deduced for long isotopical chains. New results on the enhancement of the nuclear level density in spherical and deformed nuclei due to collective rotational and vibrational excitations were obtained. Using these reaction products as secondary beams, the dipole giant resonance was excited by electromagnetic interactions in a secondary lead target, and fission from excitation energies around 11 MeV was induced. The fission fragments were identified in nuclear charge, and their velocity vectors were determined. Elemental yields and total kinetic energies have been determined for a number of neutron-deficient actinides and preactinides which were not accessible with conventional techniques. The characteristics of multimodal fission of nuclei around ²²⁶Th were systematically investigated and related to the influence of shell effects on the potential energy and on the level density between fission barrier and scission. A systematic view on the large number of elemental yields measured gave rise to a new interpretation of the enhanced production of even elements in nuclear fission and allowed for a new understanding of pair breaking in large-scale collective motion. (orig.)

[en] We report on an experimental programme to measure the nuclide production in fission in inverse kinematics. Using relativistic beams of primordial and radioactive nuclei, new experimental information on the influence of shell effects on fission has been obtained. The transition from symmetric to asymmetric fission around ²²⁷Th has systematically been mapped. The heavy asymmetric component was found to be astonishingly stable near Z = 54 for all systems investigated. (orig.)

[en] Nuclear-charge yields of fragments produced by fission of ^214,...,223Ac, ^220,...,229Th, ^224,...,232Pa, and ^231,...,234U have been measured. These radioactive nuclei were produced as secondary beams, and fission was induced in flight at 420 A MeV by electromagnetic excitation in a lead target. The excitation-energy distribution at fission is estimated to be centered at 11 MeV. The nuclear-charge distributions of the fission fragments of odd-Z actinium and protactinium isotopes show a pronounced odd-even structure: in asymmetric charge splits, the unpaired proton predominantly sticks to the heavy fragment. A model is proposed which attributes this effect to the single-particle level densities of the nascent fission fragments. This model also explains the strongly enhanced odd-even effect observed in the most asymmetric parts of the nuclear-charge distributions after fission of the even-Z nuclei ^220,...,229Th and ^231,...,234U. It is concluded that proton pairs are broken in an early stage of the fission process. (orig.)