No abstract available

[en] Using a magnetic spectrometer pions, kaons and protons were detected in mass-symmetric heavy ion reactions from C+C to Au+Au and at incident energies between 0.6 and 2.0 A·GeV. The center-of-mass pion spectra deviate from a Boltzmann distribution for all collision systems. Results are presented indicating that high-energy pions are emitted at an early stage of the collision. This is based on (i) a comparison of π⁺ and π^- spectra and (ii) the shielding of pions by spectator matter in peripheral collisions

No abstract available

[en] Hot nuclei which decay by multifragmentation can be produced either with heavy projectiles at intermediate energies or with very light projectiles at relativistic energies. The authors have studied the reaction α + Au at 1 and 3.65 GeV/nucleon at the synchrophasotron in Dubna using the new 4π setup FASA (S.P Avdeyev et al., NIM A (in print)), since all fragments originate from the target and compression should be negligible. By triggering on one IMF very high IMF multiplicities are observed corresponding to primary IMF multiplicities of 3.6 and 5.3 at 1 and 3.65 GeV/nucleon, respectively. This 50% increase demonstrates the still increasing energy deposit at these high incident energies. The relative velocities of IMF-IMF coincidences at large relative angles decrease both with incident energy and with increasing IMF multiplicity. This decrease of the mutual Coulomb repulsion could be interpreted as an increasing breakup volume of the decaying system. Together with the observed suppression of IMF-IMF coincidences at small correlation angles, the data support the scenario of a simultaneous breakup of a very dilute system

No abstract available

[en] In the study of elastic alpha scattering on sup(12,14)C, ¹⁵N, sup(16,18)O between 22 and 29 MeV it was assumed that the angular distribution is dominated by two processes. At forward angles the optical model gives a good description of the diffraction pattern, while at back angles it fails if one does not change the parameters drastically. The backangle part strongly resembles the square of a Legendre polynomial, which suggests a resonance phenomena. To parametrize a rosonance a Regge pole incorporated in the product - representation of the S-matrix was used. (Z.M.)

[en] Published in summary form only

[en] Published in summary form only

[en] A review of pion emission in heavy ion collisions is given and it is discussed whether these spectra and the various particle yields can be interpreted within a thermal model with an emission at a unique temperature. A careful inspection of the high-energy pions reveals that they are emitted during the early phase of the collisions while pions with lower energies are emitted mainly later and over a long time interval. (author)

[en] A review of strange particle production in heavy ion collisions at incident energies from SIS up to collider energies is presented. A statistical model assuming chemical equilibrium and local strangeness conservation (i.e. strangeness conservation per collision) describes most of the observed features. It is demonstrated that the K^- production at SIS energies occurs predominantly via strangeness exchange and that this channel is approaching chemical equilibrium. The observed maximum in the K⁺/π⁺ excitation function is also seen in the ratio of strange to non-strange particle production. The appearance of this maximum around 30 AGeV is due to the energy dependence of the chemical freeze-out parameters temperature T and baryo-chemical potential μ_B. (author)