Properties of high-energy pions emitted from heavy-ion collisions at 1 GeV/nucleon

Müntz, C.; Baltes, P.; Oeschler, H.; Sartorius, Alexander; Wagner, A.; Ahner, W.; Barth, Rolf F.; Cieślak, M.; Dębowski, M.; Grosse, E.; Henning, W.; Koczoń, P.; Miśkowiec, D.; Schicker, R.; Senger, P.; Bormann, C.; Brill, Dieter R.; Shin, Y.; Stein, J.; Stock, R.; Ströbele, H.; Kohlmeyer, B.; Pöppl, H.; Pühlhofer, F.; Speer, John G.; Völkel, K.; Waluś, W.

doi:10.1007/bf01298905

Cited by 36 publications

(11 citation statements)

References 23 publications

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“…This scenario is also supported by the experimental observation, that the multiplicity of high-energy pions (E kin c.m. ≥ 0.45 GeV) increases more than linearly with the number of participating nucleons [22]. This behavior is a signature of pion production via multiple baryon-baryon collisions which occur more frequently at higher densities.…”

mentioning

confidence: 91%

Evidence for different freeze-out radii of high- and low-energy pions emitted in Au+Au collisions at 1 A·GeV

et al. 1998

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Double differential production cross sections of π − and π + mesons and the number of participating protons have been measured in central Au+Au collisions at 1 A·GeV. At low pion energies the π − yield is strongly enhanced over the π + yield. The energy dependence of the π − /π + ratio is assigned to the Coulomb interaction of the charged pions with the protons in the reaction zone. The deduced Coulomb potential increases with increasing pion c.m. energy. This behavior indicates different freeze-out radii for different pion energies in the c.m. frame.Relativistic heavy ion collisions are a unique tool to study nuclear matter at high densities and temperatures [1]. At bombarding energies around 1 A·GeV, baryonic densities of 2-3 times normal nuclear matter density (ρ 0 = 0.17 fm −3 ) are expected to be reached during a time span of 10-15 fm/c (see e.g.: [2]). Thereafter, the high pressure built up in the reaction zone drives the system apart and particles freeze out according to their mean free path. A major experimental challenge is to determine the baryonic density in the different stages of the reaction.

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confidence: 91%

Evidence for different freeze-out radii of high- and low-energy pions emitted in Au+Au collisions at 1 A·GeV

et al. 1998

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“…The comparison between model predictions and experimental data is collected in table 2. Only the ratio η/π 0 does not fit reasonably in thermal model scheme, but [21] it serves as a clear indication of incompleteness of the thermalized ideal gas model considered. Apart from that, the other measured hadronic ratios are well described by the model.…”

Section: Production Ratios In Gsi Ni+ni Experiments At 2 Gev Amentioning

confidence: 90%

On the exact conservation laws in thermal models and the analysis of AGS and SIS experimental results

Keränen¹,

Cleymans²,

Suhonen³

1999

J. Phys. G: Nucl. Part. Phys.

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Abstract. The production of hadrons in relativistic heavy ion collisions is studied using a statistical ensemble with thermal and chemical equilibrium. Special attention is given to exact conservation laws, i.e. certain charges are treated canonically instead of using the usual grand canonical approach. For small systems, the exact conservation of baryon number, strangeness and electric charge is to be taken into account. We have derived compact, analytical expressions for particle abundances in such ensemble. As an application, the change in K/π ratios in AGS experiments with different interaction system sizes is well reproduced. The canonical treatment of three charges becomes impractical very quickly with increasing system size. Thus, we draw our attention to exact conservation of strangeness, and treat baryon number and electric charge grand canonically. We present expressions for particle abundances in such ensemble as well, and apply them to reproduce the large variety of particle ratios in GSI SIS 2 A GeV Ni-Ni experiments. At the energies considered here, the exact strangeness conservation fully accounts for strange particle suppression, and no extra chemical factor is needed.

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“…Furthermore, the magnitude of nuclear stopping may have a direct relationship with the enhancement of R cp . Besides, some other physical quantities, such as radial flow, temperature and viscosity, can also provide abundant information about dense hadronic matter formed in heavy ion collisions [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Medium effect on the nuclear modification factor of protons and pions in intermediate-energy heavy ion collisions

Chen

et al. 2017

Phys. Rev. C

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Nuclear modification factor (Rcp) of protons and pions are investigated by simulating Au + Au collisions from 0.8 to 1.8A GeV in a framework of an isospin-dependent quantum molecular dynamics (IQMD) model. Rcp of protons rises with the increase of pT at different beam energies owing to radial flow and Cronin effect. The rate of increase of Rcp is suppressed at higher beam energies. The significant difference of Rcp between protons and pions indicates different medium effects between protons and pions. By changing the in-medium nucleon-nucleon cross section, the Rcp of protons changes a lot, while the Rcp of pions does not. Taking the pion absorption into account, the Rcp of pions becomes close to unity without pT dependence after deactivating the reaction πN → ∆, while there is nearly no change on proton. This suggests that the pion absorption plays a dominant role on pion dynamics and have slight effect for proton dynamics.

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Properties of high-energy pions emitted from heavy-ion collisions at 1 GeV/nucleon

Cited by 36 publications

References 23 publications

Evidence for different freeze-out radii of high- and low-energy pions emitted in Au+Au collisions at 1 A·GeV

Evidence for different freeze-out radii of high- and low-energy pions emitted in Au+Au collisions at 1 A·GeV

On the exact conservation laws in thermal models and the analysis of AGS and SIS experimental results

Medium effect on the nuclear modification factor of protons and pions in intermediate-energy heavy ion collisions

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