Using the large acceptance apparatus FOPI, we study central collisions in the reactions (energies in A GeV are given in parentheses): 40Ca + 40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), 58Ni + 58Ni (0.15, ...0.25, 0.4), 96Ru + 96Ru (0.4, 1.0, 1.5), 96Zr + 96Zr (0.4, 1.0, 1.5), 129Xe + CsI (0.15, 0.25, 0.4), 197Au + 197Au (0.09, 0.12, 0.15, 0.25, 0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include cluster multiplicities, longitudinal and transverse rapidity distributions and stopping, and radial flow. The data are compared to earlier data where possible and to transport model simulations.
Using the large acceptance apparatus FOPI, we study central and semi-central collisions in the reactions (energies in A GeV are given in parentheses): 40Ca+40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), ...58Ni+58Ni (0.15, 0.25, 0.4), 96Ru+96Ru (0.4, 1.0, 1.5), 96Zr+96Zr (0.4, 1.0, 1.5), 129Xe+CsI (0.15, 0.25, 0.4), 197Au+197Au (0.09, 0.12, 0.15, 0.25, 0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include directed and elliptic flow. The data are compared to earlier data where possible and to transport model simulations. A stiff nuclear equation of state is found to be incompatible with the data. Evidence for extra-repulsion of neutrons in compressed asymmetric matter is found.
We present the first determination of the energy-dependent amplitudes of N⁎ resonances extracted from their decay in KΛ pairs in p+p→pK+Λ reactions. A combined Partial Wave Analysis of seven data ...samples with exclusively reconstructed p+p→pK+Λ events measured by the COSY-TOF, DISTO, FOPI and HADES Collaborations in fixed target experiments at kinetic energies between 2.14 to 3.5 GeV is used to determine the amplitude of the resonant and non-resonant contributions into the associated strangeness final state. The contribution of seven N⁎ resonances with masses between 1650 MeV/c2 and 1900 MeV/c2 for an excess energy between 0 and 600 MeV has been considered. The Σ–p cusp and final state interactions for the p–Λ channel are also included as coherent contributions in the PWA. The N⁎ contribution is found to be dominant with respect to the phase space emission of the pKΛ+ final state at all energies demonstrating the important role played by both N⁎ and interference effects in hadron–hadron collisions.
Using the large acceptance apparatus FOPI, we study pion emission in the reactions (energies in
A
GeV
are given in parentheses):
40Ca
+
40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93),
96Ru
+
96Ru (0.4, 1.0, ...1.5),
96Zr
+
96Zr (0.4, 1.0, 1.5),
197Au
+
197Au (0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include longitudinal and transverse rapidity distributions and stopping, polar anisotropies, pion multiplicities, transverse momentum spectra, ratios
(
π
+
/
π
−
)
of average transverse momenta and of yields, directed flow, elliptic flow. The data are compared to earlier data where possible and to transport model simulations.
.
The production of K
+
, K
-
and
(1020) mesons is studied in Al+Al collisions at a beam energy of 1.9A GeV which is close to or below the production threshold in NN reactions. Inverse slopes, ...anisotropy parameters, and total emission yields of K
±
mesons are obtained. A comparison of the ratio of kinetic energy distributions of K
-
and K
+
mesons to the HSD transport model calculations suggests that the inclusion of the in-medium modifications of kaon properties is necessary to reproduce the ratio. The inverse slope and total yield of
mesons are deduced. The contribution to K
-
production from
meson decays is found to be
%. The results are in line with the previous K
±
and
data obtained for different colliding systems at similar incident beam energies.
We present measurements of the excitation function of elliptic flow at midrapidity in Au+Au collisions at beam energies from 0.09 to 1.49 GeV per nucleon. For the integral flow, we discuss the ...interplay between collective expansion and spectator shadowing for three centrality classes. A complete excitation function of transverse momentum dependence of elliptic flow is presented for the first time in this energy range, revealing a rapid change with incident energy below 0.4 AGeV, followed by an almost perfect scaling at the higher energies. The equation of state of compressed nuclear matter is addressed through comparisons to microscopic transport model calculations.
PDF
