title: Observation of direct photons in central 158A GeV (208)P(208)b+Pb collisions
abstract: A measurement of direct photon production in 208Pb+208Pb collisions at 158A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5<p(T)<4 GeV/c. A significant direct photon signal, compared to statistical and systematical errors, is seen at p(T)>1.5 GeV/c. The result constitutes the first observation of direct photons in ultrarelativistic heavy-ion collisions. It could be significant for diagnosis of quark-gluon-plasma formation.
authors.affiliation: University of Panjab, Chandigarh 160014, India.
authors.initials: S
authors.lastname: Nikolaev
authors.initials: P
authors.lastname: Nilsson
authors.initials: S
authors.lastname: Nishimura
authors.initials: P
authors.lastname: Nomokonov
authors.initials: J
authors.lastname: Nystrand
authors.initials: FE
authors.lastname: Obenshain
authors.initials: A
authors.lastname: Oskarsson
authors.initials: I
authors.lastname: Otterlund
authors.initials: M
authors.lastname: Pachr
authors.initials: S
authors.lastname: Pavliouk
authors.initials: T
authors.lastname: Peitzmann
authors.initials: V
authors.lastname: Petracek
authors.initials: W
authors.lastname: Pinganaud
authors.initials: F
authors.lastname: Plasil
authors.initials: U
authors.lastname: Poblotzki
authors.initials: ML
authors.lastname: Purschke
authors.initials: J
authors.lastname: Rak
authors.initials: R
authors.lastname: Raniwala
authors.initials: S
authors.lastname: Raniwala
authors.initials: VS
authors.lastname: Ramamurthy
authors.initials: NK
authors.lastname: Rao
authors.initials: F
authors.lastname: Retiere
authors.initials: K
authors.lastname: Reygers
authors.initials: G
authors.lastname: Roland
authors.initials: L
authors.lastname: Rosselet
authors.initials: I
authors.lastname: Roufanov