Centrality dependence of pion freeze-out radii in Pb-Pb collisions at s NN =2.76 TeV CENTRALITY DEPENDENCE of PION FREEZE-OUT ... J. ADAM et al.

ALICE Collaboration

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Abstract

We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at sNN=2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged one-dimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with (dNch/dη)1/3. This behavior is compared to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller sNN, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. The results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider.

Original languageEnglish
Article number024905
JournalPhysical Review C - Nuclear Physics
Volume93
Issue number2
DOIs
Publication statusPublished - febr. 4 2016

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pions
collisions
radii
ionic collisions
hydrodynamics
transverse momentum
configurations
predictions

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

@article{63eb3bf19fca45c499df8458ee442d0b,
title = "Centrality dependence of pion freeze-out radii in Pb-Pb collisions at s NN =2.76 TeV CENTRALITY DEPENDENCE of PION FREEZE-OUT ... J. ADAM et al.",
abstract = "We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at sNN=2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged one-dimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with (dNch/dη)1/3. This behavior is compared to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller sNN, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. The results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider.",
author = "{ALICE Collaboration} and J. Adam and D. Adamov{\'a} and Aggarwal, {M. M.} and {Aglieri Rinella}, G. and M. Agnello and N. Agrawal and Z. Ahammed and Ahn, {S. U.} and I. Aimo and S. Aiola and M. Ajaz and A. Akindinov and Alam, {S. N.} and D. Aleksandrov and B. Alessandro and D. Alexandre and {Alfaro Molina}, R. and A. Alici and A. Alkin and Almaraz, {J. R M} and J. Alme and T. Alt and S. Altinpinar and I. Altsybeev and {Alves Garcia Prado}, C. and C. Andrei and A. Andronic and V. Anguelov and J. Anielski and T. Antičić and F. Antinori and P. Antonioli and L. Aphecetche and H. Appelsh{\"a}user and S. Arcelli and N. Armesto and R. Arnaldi and Arsene, {I. C.} and M. Arslandok and B. Audurier and A. Augustinus and R. Averbeck and Azmi, {M. D.} and M. Bach and G. Benc{\'e}di and D. Ber{\'e}nyi and G. Hamar and G. Kiss and S. Pochybov{\'a} and D. Varga",
year = "2016",
month = "2",
day = "4",
doi = "10.1103/PhysRevC.93.024905",
language = "English",
volume = "93",
journal = "Physical Review C - Nuclear Physics",
issn = "0556-2813",
publisher = "American Physical Society",
number = "2",

}

TY - JOUR

T1 - Centrality dependence of pion freeze-out radii in Pb-Pb collisions at s NN =2.76 TeV CENTRALITY DEPENDENCE of PION FREEZE-OUT ... J. ADAM et al.

AU - ALICE Collaboration

AU - Adam, J.

AU - Adamová, D.

AU - Aggarwal, M. M.

AU - Aglieri Rinella, G.

AU - Agnello, M.

AU - Agrawal, N.

AU - Ahammed, Z.

AU - Ahn, S. U.

AU - Aimo, I.

AU - Aiola, S.

AU - Ajaz, M.

AU - Akindinov, A.

AU - Alam, S. N.

AU - Aleksandrov, D.

AU - Alessandro, B.

AU - Alexandre, D.

AU - Alfaro Molina, R.

AU - Alici, A.

AU - Alkin, A.

AU - Almaraz, J. R M

AU - Alme, J.

AU - Alt, T.

AU - Altinpinar, S.

AU - Altsybeev, I.

AU - Alves Garcia Prado, C.

AU - Andrei, C.

AU - Andronic, A.

AU - Anguelov, V.

AU - Anielski, J.

AU - Antičić, T.

AU - Antinori, F.

AU - Antonioli, P.

AU - Aphecetche, L.

AU - Appelshäuser, H.

AU - Arcelli, S.

AU - Armesto, N.

AU - Arnaldi, R.

AU - Arsene, I. C.

AU - Arslandok, M.

AU - Audurier, B.

AU - Augustinus, A.

AU - Averbeck, R.

AU - Azmi, M. D.

AU - Bach, M.

AU - Bencédi, G.

AU - Berényi, D.

AU - Hamar, G.

AU - Kiss, G.

AU - Pochybová, S.

AU - Varga, D.

PY - 2016/2/4

Y1 - 2016/2/4

N2 - We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at sNN=2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged one-dimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with (dNch/dη)1/3. This behavior is compared to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller sNN, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. The results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider.

AB - We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at sNN=2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged one-dimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with (dNch/dη)1/3. This behavior is compared to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller sNN, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. The results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider.

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U2 - 10.1103/PhysRevC.93.024905

DO - 10.1103/PhysRevC.93.024905

M3 - Article

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VL - 93

JO - Physical Review C - Nuclear Physics

JF - Physical Review C - Nuclear Physics

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