Azimuthal asymmetry of neutral pion emission in Au+Au reactions at 1 GeV/nucleon

Venema, L.B.; Braak, H.; Löhner, H.; Ae, Raschke; Rh, Siemssen; Šumbera, M.; Wilschut, HW; Berg, F.D. van den; Kühn, W.; Metag,; Notheisen, M.; Novotny, R.; Pfeiffer, M.; Ritman, J.; Schwalb, O.; Gobbi, A.; Kd, Hildenbrand; Hlaváč, S.; Holzmann, R.; Rs, Simon; Sodan, U.; Teh, K.; Jp, Wessels; Herrmann, N.; Wienold, T.; Kötte, R.; Mösner, J.; Neubert, W.; Wohlfarth, D.; Ostendorf, R.W.; Schutz, Y.; Brummund, N.; Santo, R.

doi:10.1103/physrevlett.71.835

Cited by 70 publications

(22 citation statements)

References 21 publications

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“…3.8 which demonstrate for the first time experimentally that pion emission is correlated to the reaction dynamics. First observations of a preferred out-of-plane emission of charged and neutral pions ("squeeze-out") were reported by the KaoS and TAPS collaborations [100,101]. The azimuthal anisotropy was most pronounced for pions with high transverse momenta in semicentral collisions.…”

Section: Angular Distributionsmentioning

confidence: 99%

Hadronic particle production in nucleus-nucleus collisions

Senger¹,

Ströbele

1999

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

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Data on hadronic particle production in symmetric nuclear collisions from SIS/BEVALAC to SPS energies are reviewed. The main emphasis is put on the production of pions, kaons, and antibaryons. Global features will be discussed in terms of rapidity and transverse momentum distributions and the total energy stored in produced particles. Pion and kaon production probabilities are studied as function of beam energy and their distribution in polar and azimuthal angle. Special emphasis is put on medium effects expected for kaons in dense nuclear matter at low energies. An enhanced strange particle yield is found at all energies, its explanation at SPS energies is still controversial. Experimental data on antibaryon and multistrange hyperon production is less complete and does not allow for similar systematic studies.

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Section: Angular Distributionsmentioning

confidence: 99%

Hadronic particle production in nucleus-nucleus collisions

Senger¹,

Ströbele

1999

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

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“…A quantitative comparison of calculated and measured spectra is in progress [14]. The azimuthally anisotropic emission most pronounced for high-energy pions [22,23] supports this interpretation concerning the time scale of the pion emission.…”

Section: Spectral Distributionsmentioning

confidence: 56%

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

Müntz

Baltes

Oeschler

et al. 1995

Z. Physik A - Hadrons and Nuclei

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Abstract.Positively charged pions and protons from collisions of Ne+NaF and Au+Au at 1 GeV/nucleon incident energy were measured near midrapidity. The center-of-mass pion spectra deviate from a Maxwell-Boltzmann distribution. The slope of the high-energy part of the pion spectra varies significantly with the system mass and little with the size of the reaction zone. While the total pion yield rises linearly with the number of participant nucleons, the highenergy component increases more than linearly. PACS: 25.75.+rSeveral previous investigations have reported a deviation of the pion transverse momentum spectrum from a thermal distribution [2,8,9,10]. The low-energy part of the spectrum was interpreted as resulting from decaying A resonances while the high-energy part remained unexplained. In the present paper, energy spectra of positive pions and protons emitted near midrapidity for two mass-symmetric systems, Au+Au and Ne+NaF, at 1 GeV/nucleon incident energy are studied as a function of the size of the reaction zone. Emphasis is put on the study of high-energy pions which have been measured with high statistics up to total energies of 840 MeV in the midrapidity frame.

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“…In this case the geometry of the participant zone favors the preferential in-plane emission of pions [25,34,35] and hence positive elliptic flow, which was observed recently at AGS [21] and SPS [22,23] energies. However already at SIS in-plane emission of low energy pions were observed, see [16]. Hence similar scenario can hold for low energy pions even at SIS energies.…”

Section: Introductionmentioning

confidence: 55%

“…This effect was interpreted as a dynamical squeeze-out of nuclear matter due to the build-up of pressure in the interaction zone between two colliding nuclei [30]. Similar to baryons, negative elliptic flow was observed for high transverse momentum neutral and charged pions emitted at midrapidity in 1 AGeV Au+Au collisions at SIS (GSI) [16,17]. However, the observed pion anisotropy was not been attributed to the expansion of nuclear matter, but rather to the strong final state interactions of pions with cold spectator matter transiently concentrated in the reaction plane ("shadowing").…”

Section: Introductionmentioning

confidence: 99%

Elliptic flow of ν ands π 0 mesons in heavy-ion collisions at 2 A GeVmesons in heavy-ion collisions at 2 A GeV

Taranenko

Куглер

2000

Czech J Phys

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Azimuthal distributions of η and π 0 mesons emitted at midrapidity in collisions of 1.9 AGeV 58 Ni+ 58 Ni and 2 AGeV 40 Ca+ nat Ca are studied as a function of the number of projectile-like spectator nucleons. The observed anisotropy corresponds to a negative elliptic flow signal for η mesons, indicating a preferred emission perpendicular to the reaction plane. In contrast, only small azimuthal anisotropies are observed for π 0 mesons. This may indicate that η mesons freeze out earlier from the fire ball than pions.

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Azimuthal asymmetry of neutral pion emission in Au+Au reactions at 1 GeV/nucleon

Cited by 70 publications

References 21 publications

Hadronic particle production in nucleus-nucleus collisions

Hadronic particle production in nucleus-nucleus collisions

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

Elliptic flow of ν ands π 0 mesons in heavy-ion collisions at 2 A GeVmesons in heavy-ion collisions at 2 A GeV

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