[en] A review of the present experimental situation of intermediate energy heavy ion reactions is presented. The energy range discussed is 20-250A MeV i.e. close to the interval between the nuclear ''speed of sound energy'' and the pion production threshold. Some approaches from low energy - as well as high energy nuclear reaction physics are discussed. (author)

[en] A weak two-proton azimuthal angle back-to-back correlation which may indicate the presence of quasi-elastic first order proton-proton scattering in ¹⁶O + CNO reactions at 2 GeV/nucleon has been observed. Low and medium multiplicity ¹⁶O + AgBr reactions show the same tendency, while the dominant feature of the two-proton azimuthal angle distribution for very high multiplicity events is a blockade against pairs with relative angles between 2π/3 and 7π/8. (Auth.)

[en] The results from the first generation of experiments at the CERN synchrocyclotron with 30A MeV - 85A MeV ¹²C beams are beginning to manifest the pattern of heavy ion reactions in the region between the binary low energy side and the 'chaotic' high energy side. Results from experiments on the production of p, d, and pi at these energies are presented. (Author)

[en] The accelerator system under construction in Uppsala with the ECR-source + the K equals 200 synchrocyclotron + the CELSIUS synchrotron ring for storage, cooling and acceleration opens up possibilities for a very fruitful heavy ion physics program. Some recently obtained results and some recent ideas on intermediate energy reactions are discussed and speculations are made about some experiments where the unconventional qualities of CELSIUS beams could be utilized. (author)

[en] Experimental results from devoted medium energy heavy ion accelerators are beginning to fill up the gap in our knowledge of the heavy ion reaction pattern between the low energy - binary - side and the high energy - participant/spectator - side. This paper is focused on new results on central, violent collisions in the medium energy region. 42 refs. (author)

[en] Heavy ion interactions in nuclear emulsions induced by 2 GeV/nucleon ¹⁶O have been studied. The reaction cross sections determined are 337+56-85 mb, 1007+175-174 mb and 2180+304-231 mb for interactions with H, CNO and AgBr, respectively. Energy and transverse momentum distributions of non-relativistic protons (E<400 MeV) and all He nuclei have been analysed. Statistical models assuming small correlations among nucleon momenta can account for the main part of the He emission. The energy- and transverse momentum distributions of protons emitted from light as well as heavy target nuclei indicate that intranuclear nucleon-nucleon scattering is the most important proton emission process. The angular distributions of both high energy protons and high energy He nuclei emitted from the target nucleus differ considerably in central and peripheral ¹⁶O-AgBr interactions. In order to explain the angular distributions of high energy protons and He nuclei in events with extremely small impact parameter, non-statistical phenomena, possibly hydrodynamic shock wave emission, must be considered. (Auth.)

[en] Computer simulations of low statistics track detector heavy ion collision experiments on projectile fragmentation are presented. We find a non-negligible probability to obtain the recently observed anomalous fragmentation component also with normal fragmentation processes. We discuss the significance of the expected mean-free-path behaviour when an anomalous component is included. (author)

[en] Angular distributions of high energy He nuclei, emitted from the target in central ¹⁶O-AgBr interactions, are found to be highly forward-peaked at 0.2 GeV/nucleon but almost isotropic at 2 GeV/nucleon. The angular distributions are in qualitative agreement with recent shock wave calculations. However, no narrow peaks are observed either in the angular or in the energy distributions of He nuclei. (Auth.)

[en] Some aspects of heavy ion reactions at high energies are considered. Particular attention is paid to central collisions and their selection from other events. Experimental results on multiple production, proton, pion and light fragment emission in such collisions and central Fe induced reactions are discussed. It is pointed out that the study of central heavy ion reactions can help to answer many fundamental questions, for example, the short distance behaviour of nuclear wave functions

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