Collective flow in heavy ion collisions at intermediate energies

We present results of a flow analysis for the set of reactions of 124,129Xe projectiles and 112,124Sn targets at incident energies 100 and 150 A MeV studied with the INDRA detector at GSI. The dependence on centrality and on p_t of the directed and elliptic flow are determined for isotopically selected reaction products with Z \le 3. The flow parameters v_1 and v_2, in general, follow expected trends but isotopic effects are small.Comment: 3 pages, 2 figures, contributed talk at INPC, Tokyo, June 3-8, 2007, to appear in the proceeding

Shunning Uncertainty: The Neglect of Learning Opportunities

Financial, managerial, and medical decisions often involve alternatives whose possible outcomes have uncertain probabilities. In contrast to alternatives whose probabilities are known, these uncertain alternatives offer the benefits of learning. In repeat-choice situations, such learning brings value. If probabilities appear favorable (unfavorable), a choice can be repeated (avoided). In a series of experiments involving bets on the colors of poker chips drawn from bags, decision makers often prove to be blind to the learning opportunities offered by uncertain probabilities. Such decision makers violate rational decision making and forgo significant expected payoffs when they shun uncertain alternatives in favor of risky ones. Worse, when information is revealed, many make choices contrary to learning. A range of factors explain these violations. The results indicate that priming with optimal strategies offers little improvement.

Modification of surface energy in nuclear multifragmentation

Within the statistical multifragmentation model we study modifications of the surface and symmetry energy of primary fragments in the freeze-out volume. The ALADIN experimental data on multifragmentation obtained in reactions induced by high-energy projectiles with different neutron richness are analyzed. We have extracted the isospin dependence of the surface energy coefficient at different degrees of fragmentation. We conclude that the surface energy of hot fragments produced in multifragmentation reactions differs from the values extracted for isolated nuclei at low excitation. At high fragment multiplicity, it becomes nearly independent of the neutron content of the fragments.Comment: 11 pages with 13 figure