Abstract
The first measurement of direct photons in collisions at is presented. The direct photon signal is extracted as a function of the collision centrality and compared to next-to-leading order perturbative quantum chromodynamics calculations. The direct photon yield is shown to scale with the number of nucleon-nucleon collisions for all centralities.
- Received 7 March 2005
DOI:https://doi.org/10.1103/PhysRevLett.94.232301
©2005 American Physical Society