[en] The GSI experimental program has been restored and the first experiments from the Phase 0 will be conducted. The scientific program of the NuStAR collaboration (Nuclear Structure, Astrophysics and Reactions) is planned to begin in April 2020 with experiments using newly developed FATIMA and AIDA detector systems for FAIR. GSI is an accelerator complex in Germany. The laboratory has a complex of accelerators (linear UNILAC injector and synchrotron SIS-18) for acceleration of heavy nuclei, incl. ²³⁸U. Each of the GSI experiments is unique and aims to study a nuclear characteristic in a particular nucleus or group of nuclei, but for all experiments in a campaign a common experimental setup is used which can be fine-tuned to the specific experiment.

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[en] Coulomb fission of ²³⁸U has been studied in the interaction of a 24.3 MeV/nucleon U beam with an Au target. A novel experimental approach is followed, allowing to isolate the Coulomb fission from the nuclear fission on an event by event basis. The Z distribution of the fragments is studied for both fission processes. (author)

[en] The need of sources of energy different from fossil fuels is nowadays a crucial point. As the EU-SET Plan points out, it is necessary to investigate new concepts for nuclear systems to improve the sustainability of nuclear energy. These concepts cover from energy production, through both advanced light water reactors and fast reactors foreseen in generation IV, to minimization and discharge of nuclear waste through subcritical fast systems (ADS). Despite many previous measurements and recent efforts, the present knowledge of basic nuclear data is still inadequate to fulfill the precision and accuracy required for the design and development of these new technologies. In this context the Nuclear Energy Agency addresses the most relevant isotopes, decay data, nuclear reaction channels and energy ranges that have to be investigated in more detail in the NEA High Priority Request List. The measurement of ²³⁸U(n,g) reaction cross section falls within this list because of its importance for the security of operating light water reactors and the design of generation IV reactors. Even if the number of measurements present in the EXFOR database is large, inconsistencies are still present for the ²³⁸U capture cross section both in the low energy and in the unresolved resonance region. This uncertainty influences both fast and thermal reactor systems, and contributes to the uncertainty on Pu isotope density at the end of fuel cycles. As such, there is a proposal of three independent measurement of the ²³⁸U(n,g) cross section in order to reach the required precision of 2% within an energy range from few eV to hundreds of keV. One measurement was performed at the EC-JRC-IRMM facility GELINA, while the other two at the n_TOF facility at CERN. Combined together they should lead to the desired accuracy. Here the preliminary results of the ²³⁸U(n,g) cross section measurement are presented, which was performed at n_TOF with C₆D₆ scintillation detectors on April 2012 and covers an energy range from thermal point to about 500 keV. The characteristics of the n_TOF facility, such as the very high instantaneous neutron flux, the low repetition rate and the long flight pat, i.e. the excellent energy resolution, allowed very high precision and accuracy. This, together with the detection method, would take for ²³⁸U capture cross section to a significant improvement in the unresolved resonance region and, together with the results of the other two measurements, would help to decrease the uncertainty in the resolved one down to 2%. Acknowledgement: This work is supported by the European Commission within the FP7 project ANDES (FP7-249671). (author)

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[en] Azimuthal asymmetry of significant magnitude is observed as a function of impact parameter between projectile and target fragments emitted in collisions of 0.96 A GeV ²³⁸U nuclei with Ag(Br) nuclei of emulsion. This effect is, however, not observed in collisions of two other lighter nuclei, i.e. ⁸⁴Kr at 1.52 A GeV and ¹⁶0 at 200 A GeV, with the same target nuclei in emulsion

[en] The method of high-pressure liquid chromatography was used to separate metal cations and anions. Thereby the influence of different parameters on the separation of lanthanides by cation exchange and extraction chromatography was systematically investigated. The results were used to optimize that separation cycle, in which the elements from Z = 26 to Z = 101 were separated taking into account especially the group of actinides. These separations and the subsequent spectroscopy of gamma radiation, alpha particles and spontaneous fission fragments were used to determine formation cross sections in heavy ion reactions as a function of the atomic charge and the mass number. The most important point was the investigation of the collision of ²³⁸U ions at different bombarding energies. On the basis of the measured formation cross sections conclusions can be drawn on the reaction mechanism and the excitation function of the formation of transplutonium elements. According to the results it seems to be reasonable to use transfer reactions between ²³⁸U and ²³⁸U or ²⁴⁸Cm to synthesize superheavy nuclei around Z = 114. Until now that has been tried only with the help of fusion reactions and the results were negative. (orig.)

[en] A Reply to the Comment by Thomas E. Cowan and Jack S. Greenberg. copyright 1996 The American Physical Society

[en] Following the completion of APEX in late 1993, a two-week run on the ²³⁸U + ¹⁸¹Ta system at 6.1 and 6.3 MeV/u with 1 mg/cm² targets provided, for the first time, data in which the expected sharp sum-energy lines should appear. Data from previous experiments show evidence for sharp sum-energy lines at 625, 748 and 805 keV, observed at bombarding energies from 5.9 to 6.3 MeV/u. The 625- and 809-keV lines display the characteristics of equal-energy back-to-back emission whereas the 748-keV line shows a rather different behavior. In our measurements, average beam currents of 2-3 pnA from the ATLAS accelerator were used to bombard 1-mg/cm² rolled ¹⁸¹Ta targets, the energy loss in which corresponds to the ranges of bombarding energies over which the sharp sum-energy lines were previously reported. A run at 5.95 MeV/u for ²³⁸U + ¹⁸¹Ta followed in May 1994. These data were analyzed extensively. Sum-energy spectra measured in coincidence with scattered ions in the range 20 degrees < θ < 68 degrees. No evidence is found for the sharp sum-energy lines reported previously and, depending on the scenario assumed for the production mechanism and kinematics of the pairs, upper limits on cross sections at the 90% confidence limit range from 10-100 times smaller than the values that can be deduced from the earlier reports. We are in the process of refining the data analysis and simulations of the apparatus in order to finalize these numbers for publication