Direct photons are considered as one of the most important signatures of thermalized quark-gluon matter produced in relativistic heavy-ion collisions. The ALICE experiment at LHC, which is being ...prepared to study heavy-ion collisions at the energies 5.5
A TeV, will be equipped by the photon spectrometer PHOS to detect direct photons and measure their spectrum in a wide momentum range 0
<
p
T
<
100 GeV/
c with high precision. Expected yields of direct photons at the LHC energies, as well as experimental methods to measure photon spectrum in the PHOS detector, are discussed in the paper.
It is shown that due to contribution of the hadrons, emitted directly from
the inner hot region of central heavy ion collision, radial flow of the final
state hadrons is rather sensitive to the ...creation of quark-gluon plasma with
mixed phase.
Measurements of transverse-single-spin asymmetries (A sub(N)) in p + p collisions at radicals = 62.4 and 200 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider are presented. At ...midrapidity, A sub(N) is measured for neutral pion and eta mesons reconstructed from diphoton decay, and, at forward rapidities, neutral pions are measured using both diphotons and electromagnetic clusters. The neutral-pion measurement of A sub(N) at midrapidity is consistent with zero with uncertainties a factor of 20 smaller than previous publications, which will lead to improved constraints on the gluon Sivers function. At higher rapidities, where the valence quark distributions are probed, the data exhibit sizable asymmetries. In comparison with previous measurements in this kinematic region, the new data extend the kinematic coverage in radicals and p sub(T), and it is found that the asymmetries depend only weakly on radicals. The origin of the forward A sub(N) is presently not understood quantitatively. The extended reach to higher p sub(T) probes the transition between transverse momentum dependent effects at low p sub(T) and multiparton dynamics at high p sub(T).
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