The Experts below are selected from a list of 17433 Experts worldwide ranked by ideXlab platform
Georg Wolschin - One of the best experts on this subject based on the ideXlab platform.
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Rapidity equilibration in d + Au and Au + Au systems
The European Physical Journal A, 2006Co-Authors: Georg WolschinAbstract:In a Relativistic Diffusion Model (RDM), the evolution of net-proton rapidity spectra with sqrt(s_NN) in heavy systems is proposed as an indicator for local equilibration and Longitudinal Expansion. The broad midrapidity valley recently discovered at RHIC in central Au + Au collisions at sqrt(s_NN)= 200 GeV suggests rapid local equilibration which is most likely due to deconfinement, and fast Longitudinal Expansion. Rapidity spectra of produced charged hadrons in d + Au and Au + Au systems at RHIC energies and their centrality dependence are well described in a three-sources RDM. In central collisions, about 19 % of the produced particles are in the equilibrated midrapidity region for d + Au.
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Rapidity equilibration and Longitudinal Expansion at RHIC
Europhysics Letters (EPL), 2006Co-Authors: Georg WolschinAbstract:The evolution of net-proton rapidity spectra with sqrt(s_NN) in heavy relativistic systems is proposed as an indicator for local equilibration and Longitudinal Expansion. In a Relativistic Diffusion Model, bell-shaped distributions in central collisions at AGS energies and double-humped nonequilibrium spectra at SPS show pronounced Longitudinal collective Expansion when compared to the available data. The broad midrapidity valley recently discovered at RHIC in central Au+Au collisions at sqrt(s_NN) = 200 GeV indicates rapid local equilibration which is most likely due to deconfinement, and fast Longitudinal Expansion of the locally equilibrated subsystem. A prediction is made for Au+Au at sqrt(s_NN)= 62.4 GeV.
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Diffusion and local deconfinement in relativistic systems
Nuclear Physics A, 2005Co-Authors: Georg WolschinAbstract:The evolution of net-proton rapidity spectra with s N N is heavy relativistic systems is proposed as an indicator for local equilibration, Longitudinal Expansion, and deconfinement. Bell-shaped distributions in central collisions at AGS energies and double-humped nonequilibrium spectra at SPS ishow substantial collective Expansion. The broad midrapidity valley appearing at RHIC indicates Longitudinal collective Expansion of a locally equilibrated subsystem. In central Au-Au collisions at s N N = 200 GeV , fast local equilibration which is most likely due to deconfinement is estimated in a Relativistic Diffusion Model to occur for 14 per cent of the incoming baryons.
Urs Achim Wiedemann - One of the best experts on this subject based on the ideXlab platform.
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Yano-Koonin-Podgoretskii parametrisation of the Hanbury Brown-Twiss correlator
The European Physical Journal C, 1998Co-Authors: U. Heinz, Boris Tomasik, Urs Achim WiedemannAbstract:The Yano-Koonin-Podgoretskiuo (YKP) parametrisation of Hanbury Brown-Twiss (HBT) two-particle correlation functions opens new strategies for extracting the emission duration and testing the Longitudinal Expansion in heavy-ion collisions. Based on the recently derived model-independent expressions, we present a detailed parameter study of the YKP parameters for a finite, hydrodynamically expanding source model of heavy-ion collisions. For the class of models studied here, we show that the three YKP radius parameters have an interpretation as Longitudinal extension, transverse extension and emission duration of the source in the YKP frame. This frame is specified by the fourth fit parameter, the Yano-Koonin velocity which describes to a good approximation the velocity of the fluid element with highest emissivity and allows to test for the Longitudinal Expansion of the source. Deviations from this interpretation of the YKP parameters are discussed quantitatively.
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Space-time Characteristics of the Fireball from HBT Interferometry
arXiv: Nuclear Theory, 1997Co-Authors: Boris Tomasik, U. Heinz, Urs Achim WiedemannAbstract:We present the Yano-Koonin-Podgoretskii parametrisation of the correlation function. Compared to the conventionally used Cartesian parametrisation, this one provides more straightforward measurement of the duration of the emission process in the fireball and a clearer signal of the Longitudinal Expansion, which is expected in ulrarelativistic heavy ion collisions.
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Lifetimes and sizes from two particle correlation functions
Physics Letters B, 1996Co-Authors: Ulrich Heinz, Boris Tomasik, Urs Achim WiedemannAbstract:Abstract We discuss the Yano-Koonin-Podgoretskii (YKP) parametrization of the two-particle correlation function for azimuthally symmetric expanding sources. We derive model-independent expressions for the YKP fit parameters and discuss their physical interpretation. We use them to evaluate the YKP fit parameters and their momentum dependence for a simple model for the emission function and propose new strategies for extracting the source lifetime. Longitudinal Expansion of the source can be seen directly in the rapidity dependence of the Yano-Koonin velocity.
Young-hoon Song - One of the best experts on this subject based on the ideXlab platform.
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Optimization of NH_3 Decomposition by Control of Discharge Mode in a Rotating Arc
Plasma Chemistry and Plasma Processing, 2014Co-Authors: Dae Hoon Lee, Kwan-tae Kim, Hee Seok Kang, Young-hoon SongAbstract:In this study, the characteristic behavior of a rotating arc was investigated. Various modes, depending on the electric power supplied, can be observed in a rotating arc. Each mode produces different discharge characteristics and thermal environments and, accordingly, chemical processes hosted in the plasma reaction volume can be controlled differently in each mode. General thermal to non-thermal transitions observed in a gliding arc are based on the Longitudinal Expansion of the arc column. In a rotating arc, the reverse transition or non-thermal to thermal transition can be hosted by controlling the reactor geometry. The reverse transition can be achieved by self-adjustment of the arc column where Longitudinal Expansion of the arc column is confined. The reverse transition enhances the conversion efficiency of electric power to thermal energy. Then, optimization of thermal activation was obtained by controlling the mode of operation, and it was verified using the NH_3 decomposition reaction.
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Optimization of NH3 Decomposition by Control of Discharge Mode in a Rotating Arc
Plasma Chemistry and Plasma Processing, 2013Co-Authors: Dae Hoon Lee, Kwan-tae Kim, Hee Seok Kang, Young-hoon SongAbstract:In this study, the characteristic behavior of a rotating arc was investigated. Various modes, depending on the electric power supplied, can be observed in a rotating arc. Each mode produces different discharge characteristics and thermal environments and, accordingly, chemical processes hosted in the plasma reaction volume can be controlled differently in each mode. General thermal to non-thermal transitions observed in a gliding arc are based on the Longitudinal Expansion of the arc column. In a rotating arc, the reverse transition or non-thermal to thermal transition can be hosted by controlling the reactor geometry. The reverse transition can be achieved by self-adjustment of the arc column where Longitudinal Expansion of the arc column is confined. The reverse transition enhances the conversion efficiency of electric power to thermal energy. Then, optimization of thermal activation was obtained by controlling the mode of operation, and it was verified using the NH3 decomposition reaction.
Boris Tomasik - One of the best experts on this subject based on the ideXlab platform.
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Stopping and the 〈K〉/〈π〉 Horn
AIP Conference Proceedings, 2006Co-Authors: Boris Tomasik, Evgeni E. KolomeitsevAbstract:We propose a non‐equilibrium hadronic model to interpret the observed excitation function of kaon‐to‐pion ratios in nuclear collisions at AGS and SPS energies. The crucial assumption of our model is that due to stronger stopping at lower energies the lifetime of the fireball is prolonged because the system has to build up the Longitudinal Expansion from internal pressure.
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Flow effects on the freeze-out phase-space density in heavy-ion collisions
Physical Review C, 2002Co-Authors: Boris Tomasik, Ulrich HeinzAbstract:The strong Longitudinal Expansion of the reaction zone formed in relativistic heavy-ion collisions is found to significantly reduce the spatially averaged pion phase-space density, compared to naive estimates based on thermal distributions. This has important implications for data interpretation and leads to larger values for the extracted pion chemical potential at kinetic freeze-out.
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Yano-Koonin-Podgoretskii parametrisation of the Hanbury Brown-Twiss correlator
The European Physical Journal C, 1998Co-Authors: U. Heinz, Boris Tomasik, Urs Achim WiedemannAbstract:The Yano-Koonin-Podgoretskiuo (YKP) parametrisation of Hanbury Brown-Twiss (HBT) two-particle correlation functions opens new strategies for extracting the emission duration and testing the Longitudinal Expansion in heavy-ion collisions. Based on the recently derived model-independent expressions, we present a detailed parameter study of the YKP parameters for a finite, hydrodynamically expanding source model of heavy-ion collisions. For the class of models studied here, we show that the three YKP radius parameters have an interpretation as Longitudinal extension, transverse extension and emission duration of the source in the YKP frame. This frame is specified by the fourth fit parameter, the Yano-Koonin velocity which describes to a good approximation the velocity of the fluid element with highest emissivity and allows to test for the Longitudinal Expansion of the source. Deviations from this interpretation of the YKP parameters are discussed quantitatively.
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Space-time Characteristics of the Fireball from HBT Interferometry
arXiv: Nuclear Theory, 1997Co-Authors: Boris Tomasik, U. Heinz, Urs Achim WiedemannAbstract:We present the Yano-Koonin-Podgoretskii parametrisation of the correlation function. Compared to the conventionally used Cartesian parametrisation, this one provides more straightforward measurement of the duration of the emission process in the fireball and a clearer signal of the Longitudinal Expansion, which is expected in ulrarelativistic heavy ion collisions.
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Lifetimes and sizes from two particle correlation functions
Physics Letters B, 1996Co-Authors: Ulrich Heinz, Boris Tomasik, Urs Achim WiedemannAbstract:Abstract We discuss the Yano-Koonin-Podgoretskii (YKP) parametrization of the two-particle correlation function for azimuthally symmetric expanding sources. We derive model-independent expressions for the YKP fit parameters and discuss their physical interpretation. We use them to evaluate the YKP fit parameters and their momentum dependence for a simple model for the emission function and propose new strategies for extracting the source lifetime. Longitudinal Expansion of the source can be seen directly in the rapidity dependence of the Yano-Koonin velocity.
J.g. Wang - One of the best experts on this subject based on the ideXlab platform.
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Longitudinal Expansion of space charge dominated drifting beam bunches with a parabolic line charge density distribution
Applied Physics Letters, 1993Co-Authors: J.g. Wang, D. X. Wang, M ReiserAbstract:An experiment was performed for the first time to demonstrate linear Longitudinal space‐charge forces on drifting electron beam bunches with a parabolic line charge density distribution. The parabolic electron beam bunch was produced by a gridded electron gun and guided into a short transport channel consisting of an induction acceleration module and three matching lenses. The time‐resolved beam energy was measured at the end of the channel by both a retarding field energy analyzer and a deflecting field energy analyzer. The experimental results were compared with theory and good agreement was found.
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Longitudinal Expansion of space‐charge dominated drifting beam bunches with a parabolic line charge density distribution
Applied Physics Letters, 1993Co-Authors: J.g. Wang, D. X. Wang, Martin ReiserAbstract:An experiment was performed for the first time to demonstrate linear Longitudinal space‐charge forces on drifting electron beam bunches with a parabolic line charge density distribution. The parabolic electron beam bunch was produced by a gridded electron gun and guided into a short transport channel consisting of an induction acceleration module and three matching lenses. The time‐resolved beam energy was measured at the end of the channel by both a retarding field energy analyzer and a deflecting field energy analyzer. The experimental results were compared with theory and good agreement was found.
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Longitudinal Expansion and compression of electron bunches with rectangular line charge profiles
Il Nuovo Cimento A, 1993Co-Authors: Ding-xiong Wang, J.g. Wang, D. Kehne, Martin Reiser, Irving HaberAbstract:The Longitudinal Expansion and compression of a space-charge-dominated rectangular electron bunch have been investigated at the University of Maryland Electron Beam Transport Facility. In this paper we report the experimental results and comparison with theoretical prediction and 1D PIC simulations.
