Collisions of Au on Au at incident energies of 150, 250 and 400 A MeV were studied with the FOPI-facility at GSI Darmstadt. Nuclear charge (Z ≤ 15) and velocity of the products were detected with full azimuthal acceptance at laboratory angles 1 • ≤ θ lab ≤ 30 • . Isotope separated light charged particles were measured with movable multiple telescopes in an angular range of 6 − 90 • . Central collisions representing about 1% of the reaction cross section were selected by requiring high total transverse energy, but vanishing sideflow. The velocity space distributions and yields of the emitted fragments are reported. The data are analysed in terms of a thermal model including radial flow. A comparison with predictions of the Quantum Molecular Model is presented.PACS: 25.70.Pq
Semi-inclusive triple differential multiplicity distributions of positively charged kaons have been measured over a wide range in rapidity and transverse mass for central collisions of 58 Ni with 58 Ni nuclei. The transverse mass (m t ) spectra have been studied as a function of rapidity at a beam energy 1.93 AGeV. The m t distributions of K + mesons are well described by a single Boltzmann-type function. The spectral slopes are similar to that of the protons indicating that rescattering plays a significant role in the propagation of the kaon. Multiplicity densities have been obtained as a function of rapidity by extrapolating the Boltzmann-type fits to the measured distributions over the remaining phase space. The total K + meson yield has been determined at beam energies of 1.06, 1.45, and 1.93 AGeV, and is presented in comparison to existing data. The low total yield indicates that the K + meson can not be explained within a hadro-chemical equilibrium scenario, therefore indicating that the yield does remain sensitive to effects related to its production processes such as the equation of state of nuclear matter and/or modifications to the K + dispersion relation.
Excitation functions have been measured for di6'erent fragments produced in the ' Y{' F,x)y reactions between 135 and 143.25 MeV incident energy in 250 keV steps. Cross section fluctuations correlated in atomic number and detection angle arg observed with a coherence width of 200 -500 keV. Lifetimes have been deduced and are of the order of a complete nuclear rotation. The data can be explained in terms of quasimolecular configurations and/or an orbiting situation in a dinuclear system.
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