Frankfurt Institute for Advanced Studies

About: Frankfurt Institute for Advanced Studies is a facility organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Baryon & Quark–gluon plasma. The organization has 798 authors who have published 2733 publications receiving 82799 citations. The organization is also known as: FIAS.

Decay of 202 Pb * Formed in 48 Ca+ 154 Sm Reaction Using the Dynamical Cluster-Decay Model

Abstract: The decay of compound nucleus 202Pb*, formed in entrance channel reaction 48Ca+154Sm at different incident energies, is studied by using the dynamical cluster-decay model (DCM) where all decay products are calculated as emissions of preformed clusters through the interaction barriers The calculated results show an excellent agreement with experimental data for the fusion-evaporation residue cross-section σER together with the fusion-fission cross-section σFF (taken as a sum of the energetically favored symmetric and near symmetric A=65–75 plus complementary fragments), and the competing, non-compound-nucleus quasi-fission cross-section σQF where the entrance channel is considered not to loose its identity (and hence with preformation factor P0=1) The interesting feature of this study is that the three decay processes (ER, FF and QF) are quite comparable at low energies, ER being the most dominant, whereas at higher energies FF becomes most probable followed by ER and QF The prediction of two fission windows, the symmetric fission (SF) and the near symmetric fission (nSF) whose contribution is more at lower incident energies, suggests the presence of a fine structure effect in the fusion-fission of 202Pb* This result is attributed to the shell effects (magic shells) playing effective role in the fragment preformation yields for 48Ca+154Sm reaction at lower excitation energies, giving rise to "shoulders", to an otherwise Gaussian FF mass distribution, responsible for the QF process As a further verification of this result, absence of "shoulders" (hence, the QF component) in the decay of 192Pb* due to 48Ca+144Sm reaction is also shown to be given by the calculations, in agreement with experiments The only parameter of the model is the neck-length ΔR which shows that the ER occurs first, having the largest values of ΔR, and the FF and QF processes occur almost simultaneously at lower incident energies but the FF takes over QF at higher incident energies In other words, the three processes occur in different time scales, QF competing with FF at lower incident energies

Mass- and field-shift isotope parameters for the 2s-2p resonance doublet of lithium-like ions.

Abstract: 1/2,3/2 transitions along the lithium isoelectronic sequence. Based on the multiconfiguration Dirac-Hartree-Fock method, the electron correlation and the Breit interaction are taken into account systematically. The analysis of the isotope shifts for these two transitions along the isoelectronic sequence demonstrates the importance and competition between the mass shifts and the field shifts.

Influence of temperature-dependent shear viscosity on elliptic flow at backward and forward rapidities in ultrarelativistic heavy-ion collisions

Abstract: We explore the influence of a temperature-dependent shear viscosity over entropy density ratio ${\ensuremath{\eta}}_{s}/s$ on the azimuthal anisotropies ${v}_{2}$ and ${v}_{4}$ of hadrons at various rapidities. We find that in $\mathrm{Au}+\mathrm{Au}$ collisions at full Relativistic Heavy Ion Collider energy, $\sqrt{{s}_{\mathrm{NN}}}=200\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}$, the flow anisotropies are dominated by hadronic viscosity at all rapidities, whereas in $\mathrm{Pb}+\mathrm{Pb}$ collisions at the Large Hadron Collider energy, $\sqrt{{s}_{\mathrm{NN}}}=2760\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}$, the flow coefficients are affected by the viscosity in both the plasma and hadronic phases at midrapidity, but the further away from midrapidity, the more dominant the hadronic viscosity becomes. We find that the centrality and rapidity dependence of the elliptic and quadrangular flows can help to distinguish different parametrizations of $({\ensuremath{\eta}}_{s}/s)(T)$. We also find that at midrapidity the flow harmonics are almost independent of the decoupling criterion, but they show some sensitivity to the criterion at backward and forward rapidities.

Formation of hypernuclei in heavy-ion collisions around the threshold energies

Abstract: In relativistic ion collisions there are excellent opportunities to produce and investigate hypernuclei. We have systematically studied the formation of hypernuclear spectator residues in peripheral heavy-ion collisions with the transport DCM and UrQMD models. The hyperon capture was calculated within the potential and coalescence approaches. We demonstrate that even at the beam energies around and lower than the threshold for producing $\mathrm{\ensuremath{\Lambda}}$ hyperons in binary nucleon-nucleon interactions a considerable amount of hypernuclei, including multistrange ones, can be produced. This is important for preparation of new experiments on hypernuclei in the wide energy range. The uncertainties of the predictions are investigated within the models, and the comparison with the strangeness production measured in experiments is also performed.