Studying in-medium hadron properties with HADES

Friese, J.

doi:10.1016/s0146-6410(99)00079-4

Cited by 42 publications

(2 citation statements)

References 75 publications

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“…he HADES setup is a general purpose fixed-target detector with the particular design goal of performing precise measurement of the light vector mesons ρ and ω in their leptonic decay channel. The measurement of this rare electron-positron pairs inside a huge hadronic environment, which exceeds the di-electron signal by many orders of magnitude, puts specific constraints on the apparatus [201][202][203]:…”

Section: Hades Experimentsmentioning

confidence: 99%

Collective flow measurements in Gold-Gold collisions at 1.23 AGeV with HADES

Kardan

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In this thesis, the flow coefficients vn of the orders n = 1 − 6 are studied for protons and light nuclei in Au+Au collisions at Ebeam = 1.23 AGeV, equivalent to a center-of-mass energy in the nucleon-nucleon system of √sNN = 2.4 GeV. The detailed multi-differential measurement is performed with the HADES experiment at SIS18/GSI. HADES, with its large acceptance, covering almost full azimuth angle, combined with its high mass-resolution and good particle-identification capability, is well equipped to study the azimuthal flow pattern not only for protons, deuterons, and tritons but also for charged pions, kaons, the φ-mesons, electrons/positrons, as well as light nuclei like helions and alphas. The high statistics of more than seven billion Au-Au collisions recorded in April/May 2012 with HADES enables for the first time the measurement of higher order flow coefficients up to the 6th harmonic. Since the Fourier coefficient of 7th and 8th order are beyond the statistical significance only an upper bound is given. The Au+Au collision system is the largest reaction system with the highest particle multiplicities, which was measured so far with HADES. A dedicated correction method for the flow measurement had to be developed to cope with the reconstruction in-efficiencies due to occupancies of the detector system. The systematical bias of the flow measurement is studied and several sources of uncertainties identified, which mainly arise from the quality selection criteria applied to the analyzed tracks, the correction procedure for reconstruction inefficiencies, the procedures for particle identification (PID) and the effects of an azimuthally non-uniform detector acceptance. The systematic point-to-point uncertainties are determined separately for each particle type (proton, deuteron and triton), the order of the flow harmonics vn, and the centrality class. Further, the validity of the results is inspected in the range of their evaluated systematic uncertainties with several consistency checks. In order to enable meaningful comparisons between experimental observations and predictions of theoretical models, the classification of events should be well defined and in sufficiently narrow intervals of impact parameter. Part of this work included the implementation of the procedure to determine the centrality and orientation of the reaction. In the conclusion the experimental results are discussed, including various scaling properties of the flow harmonics. It is found that the ratio v4/v2 for protons and light nuclei (deuterons and tritons) at midrapidity for all centrality classes approaches values close to 0.5 at high transverse momenta, which was suggested to be indicative for an ideal hydrodynamic behaviour. A remarkable scaling is observed in the pt dependence of v2 (v4) at mid-rapidity of the three hydrogen isotopes, when dividing by their nuclear mass number A (A^2) and pt by A. This is consistent with naive expectations from nucleon coalescence, butraises the question whether this mass ordering can also be explained by a hydrodynamical-inspired approach, like the blast-wave model. The relation of v2 and v4 to the shape of the initial eccentricity of the collision system is studied. It is found that v2 is independent of centrality for all three particle species after dividing it by the averaged second order participant eccentricity v2/⟨ε2⟩. A similar scaling is shown for v4 after division by ⟨ε2⟩^2.

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Section: Hades Experimentsmentioning

confidence: 99%

Collective flow measurements in Gold-Gold collisions at 1.23 AGeV with HADES

Kardan

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“…Besides the RHIC-BES, there are other experimental facilities around the world that can study the baryon-rich region of the phase diagram, such as the NA61/SHINE experiment at SPS [75] and the HADES experiment at GSI [76]. Among future facilities with similar goals is the CBM experiment at FAIR in Darmstadt [77], the MPD experiment at NICA in Dubna [78] and the HEF at J-PARC in Japan [79].…”

Section: Uncharted Territories Of the Qcd Phase Diagrammentioning

confidence: 99%

Experimental and phenomenological investigations of femtoscopic correlation functions in heavy- ion collisions

Kincses¹

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Introduction to heavy-ion physics and femtoscopy 1 Exploring the properties of the Quark-Gluon-Plasma 1.1 A brief history of heavy-ion physics 3 1.2 Milestones in the discovery of QGP 4 1.3 Uncharted territories of the QCD phase diagram 10 2 Experimental facilities at BNL-RHIC 13 2.1 The PHENIX experiment 13 2.2 The STAR experiment 17 3 Intensity correlations on cosmic and nuclear scales 21 3.1 Radio astronomy and HBT-correlations 21 3.2 Femtoscopy in heavy-ion physics 23 3.3 Experimental methods of femtoscopy 31

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Electromagnetic Transition Form Factors and Dilepton Decay Rates of Nucleon Resonances

et al. 2002

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Relativistic, kinematically complete phenomenological expressions for the dilepton decay rates of nucleon resonances with arbitrary spin and parity are derived in terms of the magnetic, electric, and Coulomb transition form factors. The dilepton decay rates of the nucleon resonances with masses below 2 GeV are estimated using the extended vector meson dominance (VMD) model for the transition form factors. The model provides a unified description of the photo-and electroproduction data, γ (γ * )N → N * , the vector meson decays, N * → N ϕ (ω), and the dilepton decays, N * → N + − . The constraints on the transition form factors from the quark counting rules are taken into account. The parameters of the model are fixed by fitting the available photo-and electroproduction data and using results of the multichannel partial-wave analysis of the π N scattering. Where experimental data are not available, predictions of the non-relativistic quark models are used as an input. The vector meson coupling constants of the magnetic, electric, and Coulomb types are determined. The dilepton widths and the dilepton spectra from decays of nucleon resonances with masses below 2 GeV are calculated. C 2002 Elsevier Science (USA)

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Studying in-medium hadron properties with HADES

Cited by 42 publications

References 75 publications

Collective flow measurements in Gold-Gold collisions at 1.23 AGeV with HADES

Collective flow measurements in Gold-Gold collisions at 1.23 AGeV with HADES

Experimental and phenomenological investigations of femtoscopic correlation functions in heavy- ion collisions

Electromagnetic Transition Form Factors and Dilepton Decay Rates of Nucleon Resonances

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