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Low-momentum direct-photon measurement in Cu + Cu collisions at sNN =200 GeV

Adare, A. ; Gustafsson, Hans-Åke LU ; Haslum, Eva LU ; Oskarsson, Anders LU ; Rosendahl, Sarah LU ; Silvermyr, David LU orcid ; Stenlund, Evert LU and Zou, L. (2018) In Physical Review C 98(5).
Abstract
We measured direct photons for pT<5GeV/c in minimum bias and 0%–40% most-central events at midrapidity for Cu+Cu collisions at √sNN=200GeV. The e+e− contribution from quasireal direct virtual photons has been determined as an excess over the known hadronic contributions in the e+e− mass distribution. A clear enhancement of photons over the binary scaled p+p fit is observed for pT<4GeV/c in Cu+Cu data. The pT spectra are consistent with the Au+Au data covering a similar number of participants. The inverse slopes of the exponential fits to the excess after subtraction of the p+p baseline are 285±53(stat)±57(syst)MeV/c and 333±72(stat)±45(syst)MeV/c for minimum bias and 0%–40% most-central events, respectively. The rapidity density,... (More)
We measured direct photons for pT<5GeV/c in minimum bias and 0%–40% most-central events at midrapidity for Cu+Cu collisions at √sNN=200GeV. The e+e− contribution from quasireal direct virtual photons has been determined as an excess over the known hadronic contributions in the e+e− mass distribution. A clear enhancement of photons over the binary scaled p+p fit is observed for pT<4GeV/c in Cu+Cu data. The pT spectra are consistent with the Au+Au data covering a similar number of participants. The inverse slopes of the exponential fits to the excess after subtraction of the p+p baseline are 285±53(stat)±57(syst)MeV/c and 333±72(stat)±45(syst)MeV/c for minimum bias and 0%–40% most-central events, respectively. The rapidity density, dN/dy, of photons demonstrates the same power law as a function of dNch/dη observed in Au+Au at the same collision energy. (Less)
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author
; ; ; ; ; ; and
author collaboration
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review C
volume
98
issue
5
article number
054902
publisher
American Physical Society
external identifiers
  • scopus:85057133067
ISSN
2469-9985
DOI
10.1103/PhysRevC.98.054902
language
English
LU publication?
yes
additional info
Export Date: 4 December 2018
id
083a1e0b-bb22-41ce-8f94-d32b1489cd34
date added to LUP
2018-12-04 08:49:45
date last changed
2022-03-25 06:25:32
@article{083a1e0b-bb22-41ce-8f94-d32b1489cd34,
  abstract     = {{We measured direct photons for pT&lt;5GeV/c in minimum bias and 0%–40% most-central events at midrapidity for Cu+Cu collisions at √sNN=200GeV. The e+e− contribution from quasireal direct virtual photons has been determined as an excess over the known hadronic contributions in the e+e− mass distribution. A clear enhancement of photons over the binary scaled p+p fit is observed for pT&lt;4GeV/c in Cu+Cu data. The pT spectra are consistent with the Au+Au data covering a similar number of participants. The inverse slopes of the exponential fits to the excess after subtraction of the p+p baseline are 285±53(stat)±57(syst)MeV/c and 333±72(stat)±45(syst)MeV/c for minimum bias and 0%–40% most-central events, respectively. The rapidity density, dN/dy, of photons demonstrates the same power law as a function of dNch/dη observed in Au+Au at the same collision energy.}},
  author       = {{Adare, A. and Gustafsson, Hans-Åke and Haslum, Eva and Oskarsson, Anders and Rosendahl, Sarah and Silvermyr, David and Stenlund, Evert and Zou, L.}},
  issn         = {{2469-9985}},
  language     = {{eng}},
  number       = {{5}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review C}},
  title        = {{Low-momentum direct-photon measurement in Cu + Cu collisions at sNN =200 GeV}},
  url          = {{http://dx.doi.org/10.1103/PhysRevC.98.054902}},
  doi          = {{10.1103/PhysRevC.98.054902}},
  volume       = {{98}},
  year         = {{2018}},
}