Kaon and Antikaon Production in Heavy Ion Collisions at 1.5 AGeV

At the Kaon Spectrometer KaoS at SIS, GSI the production of kaons and antikaons in heavy ion reactions at a beam energy of 1.5 AGeV has been measured for the collision systems Ni+Ni and Au+Au. The K-/K+ ratio is found to be constant for both systems and as a function of impact parameter but the slopes of K+ and K- spectra differ for all impact parameters. Furthermore the respective polar angle distributions will be presented as a function of centrality.Comment: 4 pages, 4 figures, SQM2001 in Frankfurt, Sept.2001, submitted to Journal of Physics

Cross section measurements of the Big Bang nucleosynthesis reaction D(α,γ)6LiD(\alpha,\gamma)^{6}Li by Coulomb dissociation of 6Li^{6}Li

International audienceThe possibility that big-bang nucleosynthesis (BBN) may produce nontrivial amounts of 6Li is under study since the recent observations of this element in old halo stars. However, the interpretation of these observations needs a precise knowledge of the reaction rate of D(alpha, gamma)6Li which, at present, is extremely uncertain (a factor of 20) at the energies of astrophysical interest (Ecm <= 300 keV). This uncertainty originates from difficulties in both theoretical estimates and experimental determinations of the D(alpha, gamma)6Li capture reaction cross section. New measurements of the cross section of D($\alpha, gamma$)6Li reaction using Coulomb dissociation of 6Li at 150 A MeV have been performed recently at GSI. The results will be compared to previous measurements and theoretical calculations