Observation of direct photons in central 158A GeV (208)P(208)b+Pb collisions
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.
Nikolaev
S
University of Panjab, Chandigarh 160014, India.
Nilsson
P
Nishimura
S
Nomokonov
P
Nystrand
J
Obenshain
FE
Oskarsson
A
Otterlund
I
Pachr
M
Pavliouk
S
Peitzmann
T
Petracek
V
Pinganaud
W
Plasil
F
Poblotzki
U
Purschke
ML
Rak
J
Raniwala
R
Raniwala
S
Ramamurthy
VS
Rao
NK
Retiere
F
Reygers
K
Roland
G
Rosselet
L
Roufanov
I