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Microscopic transport approaches are the tool to describe the non-equilibrium evolution in low energy collisions as well as in the late dilute stages of high-energy collisions. Here, a newly developed hadronic transport approach, SMASH (Simulating Many Accelerated Strongly-interacting Hadrons) is introduced. The overall bulk dynamics in low energy heavy ion collisions is shown including the excitation function of elliptic flow employing several equations of state. The implications of this new approach for dilepton production are discussed and preliminary results for afterburner calculations at the highest RHIC energy are presented and compared to previous UrQMD results. A detailed understanding of a hadron gas with vacuum properties is required to establish the baseline for the exploration of the transition to the quark-gluon plasma in heavy ion collisions at high net baryon densities., 4 pages, 4 figures, accepted contribution to the proceedings of Quark Matter 2018

Direct photons are a unique probe to study the properties of the medium created in heavy ion collisions. Low transverse momentum ( p T ) direct photons are of special interest since thermal photons are supposed to be dominant, while at high p T direct photons come from initial hard scattering (pQCD). PHENIX has observed a large excess of direct photon yield as well as large azimuthal anisotropy at low p T in Au+Au collisions at the c.m.s energy per nucleon pair s N N = 200 GeV. The mechanism to produce a large direct photon yield with a large elliptic anisotropy ( v 2 ) is not well understood yet. PHENIX has made systematic measurements of direct photons with different collision energies and system configurations. It has been found that direct photon yield d N γ / d η is proportional to charge particle multiplicity ( d N c h / d η ) 1 . 25 . This behavior holds for beam energies measured both at RHIC and at the LHC in large systems. This scaling suggests that there is a transition from p+p to A+A system which could be understood with the analysis of smaller systems like p+Au and d+Au.

One of the commonly used approaches, for the flow measurements in open chanel hydraulic systems, is to measure one depth and use the stable Q-H relationship to compute the flow rate. If this method is inappropriate, the velocity-area method has to be used: both area (depth) and mean velocity are measured in order to compute the flow rate. Although, it is reported that the velocity sensors operate with high uncertainty, the popularity of these methods stem from the fact that they can be applied in wide range of hydraulic conditions including the mixed flow conditions. Uncertainties are related both to the applied instruments and properties of the measurement site. While Doppler probes are preffered nowadays in the hydraulic systems, electromagnetic probes have certain adventages which are found to be useful in the methodology presented in this paper. Here, so called flat EM velocity probes are analyzed, which can be used instead of Doppler probes for the flow measurements. Due to the more rigourous operating principle, particular weighting functions can be derived in order to define contributions from different parts of the flow to the measured signal. Reduction of the uncertainty can be obtained through combination of the weighting functions with site-specific velocity fields computed with CFD simulations, In order to overcome the high uncertainty issue, additional site-specific calibration procedure for flat EM sensors is presented in this paper. Concept of its application in the engineering practice example are presented. Najčešće korišćen način merenja protoka u hidrotehničkim sistemima sa otvorenim tokom je preko merenja jedne dubine i preračunavanjem u protok korišćenjem Q-H krive. U uslovima kada nije moguće jednoznačno uspostaviti Q-H vezu, neophodno je koristiti metodu Brzina-Proticajni presek, gde se odvojeno mere (srednja) proticajna brzina i dubina. Iako su dosadašnja istraživanja pokazala da senzori brzine često rade sa visokom mernom neodređenošću, ovaj pristup je popularan zbog mogućnosti primene u širokom spektru hidrauličkih problema. Merna neodređenost u obračunatom protoku ima dvojaki karakter i rezultat je neodređenosti samog merenja brzine i dubine, kao i doprinosa usled nestandardnih uslova na mernom mestu. Iako se u hidrauličkim sistemima u poslednje vreme preferiraju ultrazvučne Dopler sonde, elekromagnetne (EM) sonde poseduju prednosti u realnim uslovima rada posebno u sistemima sa otpadnim vodama. U ovom radu, analizirane su ravne EM sonde za brzinu, koje se mogu koristiti umesto Dopler sondi za merenje protoka. Zbog jasnijeg principa rada EM sondi, moguće je definisati posebne težinske funkcije kojima se opisuje koliko koji deo polja brzina utiče na izlazni signal uređaja. Koristeći težinske funkcije u kombinaciji sa modeliranim realnim strujnim poljem, dobijenim pomoću prostornih numeričkih simulacija turbulentnog toka, moguće je smanjiti mernu neodređenost uređaja. Predložena metodologija je klasifikovana kao naknadna kalibracija EM uređaja prema uslovima na mernom mestu. Koncept njene primene je prikazan kroz praktičan primer.

In this dissertation, two nondestructive dual ridged waveguide (DRWG) material characterization systems are investigated. The single and clamped DRWG probe geometries were analyzed in previous work; however, that research only incorporated the dominant DRWG mode. Here, that restriction is removed and the existence of evanescent higher- order modes is considered. Theoretical analysis of the single and clamped DRWG probes is presented and discussed. The approach taken here is similar to that presented in previous research: Love's equivalence theorem is used to remove the DRWG apertures which are replaced with equivalent magnetic currents radiating in the presence of the background parallel-plate waveguide structure. Enforcing the continuity of the tangential magnetic fields in the DRWG and parallel- plate regions yields a system of coupled magnetic field integral equations (MFIEs). This coupled MFIE system is solved using the Method of Moments (MoM) where the tangential electric and magnetic fields in the DRWG are used as expansion and testing functions, respectively. Inversion of the resulting MoM impedance matrix produces theoretical expressions for the reflection and transmission coefficients which are numerically inverted (via nonlinear least squares) to yield estimates of the permittivity and permeability of the material under test. While the steps taken in the theoretical development are similar to previous work, the addition of higher-order modes into the analysis substantially complicates the derivation and is a significant extension of the existing dominant-mode-only literature. Lastly, simulation results of the two structures are presented. A comparison of the dominant-mode only reflection and transmission coefficients with the higher-order mode coefficients is provided.

The QCD sum rule approach to in-medium modifications of the omega meson in nuclear matter is reviewed with emphasis of its relation to 4-quark condensates and chiral symmetry restoration. Possible implications of the CB-TAPS experiment for the reaction gamma A -> A' omega (-> pi0 gamma) are sketched and the particularly important role of di-electron probes, accessible with HADES, is highlighted. A brief update of a parametrization of the previous dilepton and photon probes from CERES and WA98 of heavy-ion collisions at CERN-SPS energies is presented., Contribution to Workshop on In-Medium Hadron Physics, Giessen, Nov. 11-13; 11 pages