Model dependence of lateral distribution functions of high energy cosmic ray air showers

The influence of high and low energy hadronic models on lateral distribution functions of cosmic ray air showers for Auger energies is explored. A large variety of presently used high and low energy hadron interaction models are analysed and the resulting lateral distribution functions are compared. We show that the slope depends on both the high and low energy hadronic model used. The models are confronted with available hadron-nucleus data from accelerator experiments

Probing the density dependence of the symmetry potential at low and high densities

We investigate the sensitivity of several observables to the density dependence of the symmetry potential within the microscopic transport model UrQMD (ultrarelativistic quantum molecular dynamics model). The same systems are used to probe the symmetry potential at both low and high densities. The influence of the symmetry potentials on the yields of $\pi^{-}$, $\pi^{+}$, the $\pi^{-}/\pi^{+}$ ratio, the $n/p$ ratio of free nucleons and the $t/^3$He ratio are studied for neutron-rich heavy ion collisions ($^{208}Pb+^{208}Pb$, $^{132}Sn+^{124}Sn$, $^{96}Zr+^{96}Zr$) at $E_b=0.4A {\rm GeV}$. We find that these multiple probes provides comprehensive information on the density dependence of the symmetry potential.Comment: 15 pages, 7 figures, 2 tables. Submitted to Phys. Rev.

Phi-Meson production at RHIC, strong color fields and intrinsic transverse momenta

We investigate the effects of strong color fields and of the associated enhanced intrinsic transverse momenta on the phi-meson production in ultrarelativistic heavy ion collisions at RHIC. The observed consequences include a change of the spectral slopes, varying particle ratios, and also modified mean transverse momenta. In particular, the composition of the production processes of phi-mesons, that is, direct production vs. coalescence-like production, depends strongly on the strength of the color fields and intrinsic transverse momenta and thus represents a sensitive probe for their measurement

Directed and Elliptic Flow

We compare microscopic transport model calculations to recent data on the directed and elliptic flow of various hadrons in 2 - 10 A GeV Au+Au and Pb (158 A GeV) Pb collisions. For the Au+Au excitation function a transition from the squeeze-out to an in-plane enhanced emission is consistently described with mean field potentials corresponding to one incompressibility. For the Pb (158 A GeV) Pb system the elliptic flow prefers in-plane emission both for protons and pions, the directed flow of protons is opposite to that of the pions, which exhibit anti-flow. Strong directed transverse flow is present for protons and Lambdas in Au (6 A GeV) Au collisions as well. Both for the SPS and the AGS energies the agreement between data and calculations is remarkable.Comment: Latex, 4 pages, 3 eps-figure

Digital Media Entrepreneurship: Implications for Strategic Identity Work and Knowledge Sharing of Beginning Entrepreneurs

Digital media technologies transform the ways in which entrepreneurs communicate, organize and strategize. Yet, how strategy work is practiced as a form of “mediated” engagement with audiences through social media technologies remains a novel ground. Therefore, this paper traces the growing interdisciplinary literature and describes (1) how media is playing a more predominant role in entrepreneurship, (2) how classical media entrepreneurship is opening up, and (3) how digital media entrepreneurship (DME) emerges. Subsequently, the paper envisions how DME can be seen as a strategic practice of entrepreneurs. We discuss implications for entrepreneurial strategy work regarding entrepreneurial identity development and entrepreneurial knowledge construction, with a particular emphasis on co-location. Overall, this contributes to our understanding of strategy work of beginning entrepreneurs and sheds light on possibilities for future research

Probing the density dependence of the symmetry potential in intermediate energy heavy ion collisions

Based on the ultrarelativistic quantum molecular dynamics (UrQMD) model, the effects of the density-dependent symmetry potential for baryons and of the Coulomb potential for produced mesons are investigated for neutron-rich heavy ion collisions at intermediate energies. The calculated results of the Delta-/Delta++ and pi -/pi + production ratios show a clear beam-energy dependence on the density-dependent symmetry potential, which is stronger for the pi -/pi + ratio close to the pion production threshold. The Coulomb potential of the mesons changes the transverse momentum distribution of the pi -/pi + ratio significantly, though it alters only slightly the pi- and pi+ total yields. The pi- yields, especially at midrapidity or at low transverse momenta and the p-/pi+ ratios at low transverse momenta, are shown to be sensitive probes of the density-dependent symmetry potential in dense nuclear matter. The effect of the density-dependent symmetry potential on the production of both, K0 and K+ mesons, is also investigated

A fast hybrid approach to air shower simulations and applications

The SENECA model, a new hybrid approach to air shower simulations, is presented. It combines the use of efficient cascade equations in the energy range where a shower can be treated as one-dimensional, with a traditional Monte Carlo method which traces individual particles. This allows one to reproduce natural fluctuations of individual showers as well as the lateral spread of low energy particles. The model is quite efficient in computation time. As an application of the new approach, the influence of the low energy hadronic models on shower properties for AUGER energies is studied. We conclude that these models have a significant impact on the tails of lateral distribution functions, and deserve therefore more attention

Über die Gilch-Polymerisation und die Funktionalisierung von Poly(p-xylylen)-Derivaten

Der Mechanismus der Gilch-Polymerisation wird anhand von NMR-Experimenten genauer untersucht. Neue Copolymere aus PPX und PPV-Derivaten werden hergestellt und analysiert. Hochmolekulares Diph-PPX wird durch Polymeranaloge Umsetzung funktionalisiert

Antiflow of nucleons at the softest point of the EoS

Report-no: UFTP-492/1999 Journal-ref: Phys.Rev. C61 (2000) 024909 We investigate flow in semi-peripheral nuclear collisions at AGS and SPS energies within macroscopic as well as microscopic transport models. The hot and dense zone assumes the shape of an ellipsoid which is tilted by an angle Theta with respect to the beam axis. If matter is close to the softest point of the equation of state, this ellipsoid expands predominantly orthogonal to the direction given by Theta. This antiflow component is responsible for the previously predicted reduction of the directed transverse momentum around the softest point of the equation of state