Department of Nuclear Reactions - Overview

Research activities of the Department concentrated in 1996 on nuclear, atomic and material physics. Activities within the ALLADIN collaboration at GSI concentrated on the dependence of temperature on the excitation energy for highly excited nuclear matter. The Zbound universality obeyed by the fragment multiplicities and correlations, observed in the multifragment decay of 129Xe, 197Au and 238U projectiles with Be, C, Al, Cu, In Au and U targets at energies between 400 and 1000 MeV/nucleon, strongly suggested that the decaying pre-fragment is relatively long-lived object in thermal equilibrium The results of experiment S117, devoted to comparative study of different methods of thermometry, revelated an unexpected disagreement between the measurements of the temperature using the isotope and the population-ratio methods. The SPES4-π large detection system was completed and put into operation and the first exclusive experiments on the emission of coherent pions in the charge-exchange reactions and the excitation of the Roper resonance were carried out. Analysis of experimental data from multi-nucleon transfer reactions induced by a 50 MeV deuteron beam on 6Li was completed. The charge exchange reaction 28Si(n,p) was experimentally studied at 18.5 MeV. The breakup of 6,7Li was investigated at many energies around the Coulomb barrier. Two and three nucleon transfer reactions were experimentally studied in order to investigate homology states in 88Y and Sn isotopes. Apart from nuclear physics experiments, the 3 MV Van der Graaff accelerator was extensively used for ion beam analysis of solid states. The Rutherford Backscattering Spectroscopy and channeling methods were successfully applied for various materials. The lattice localisation of Er atoms doped in Si and GaAs crystals was investigated. Galium nitride (GaN) single crystal produced by high pressure were studied. Different types of semiconductor heterostructures were also investigated. Cross section for M,L-shell ionization of Th, U, Bi and Au atoms were measured in experiments with S ions accelerated up to 41.6 MeV