Abstract

We present results of analyses of two-pion interferometry in Au+Au collisions at √SNN=7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the BNL Relativistic Heavy Ion Collider Beam Energy Scan program. The extracted correlation lengths (Hanbury-Brown–Twiss radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equation of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.

Document Type

Article

Publication Date

7-2015

Notes/Citation Information

Published in Physical Review C: Nuclear Physics, v. 92, no. 1, article 014904, p. 1-27.

©2015 American Physical Society

The copyright holder has granted permission for posting the article here.

Collectively the authors are known as the STAR Collaboration. Due to the large number of authors involved, only the first 10 and the ones affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit the following link: http://dx.doi.org/10.1103/PhysRevC.92.014904

Digital Object Identifier (DOI)

http://dx.doi.org/10.1103/PhysRevC.92.014904

Funding Information

This work was supported in part by the Offices of NP and HEP within the US DOE Office of Science, the US NSF, CNRS/IN2P3; FAPESP CNPq of Brazil; Ministry of Education and Science of the Russian Federation; NNSFC, CAS, MoST, and MoE of China; the Korean Research Foundation; GA and MSMT of the Czech Republic; FIAS of Germany; DAE, DST, and CSIR of India; National Science Centre of Poland; National Research Foundation of the Republic of Croatia, Ministry of Science, Education and Sports of the Republic of Croatia; and RosAtom of Russia.

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