Recent results on low mass dilepton measurements from the PHENIX experiment are reported. Invariant mass spectra of \(\phi\rightarrow e^ + e^-\) are measured for the first time in Au-Au collisions at ...\(\sqrt{s_{NN}} = 200\) GeV in Run2. In d-Au collisions, the yields and MT slopes of both \(\phi\rightarrow e^ + e^-\) and \(\phi \rightarrow K^ + K^-\) are measured. Both results are consistent with each other within errors. In the future, a Hadron Blind Detector will be installed in PHENIX which will enhance our capabilities of rejecting external photon conversions and Dalitz pairs, that will result in a significant reduction of the large combinatorial background.
The PHENIX experiment at RHIC has observed a large enhancement of baryon and anti-baryon production at ~ 2-5 GeV/c, compared to expectations from jet fragmentation. While a number of theoretical ...interpretations of the data are available, there is not yet a definitive answer to the “baryon puzzle”. We investigate the centrality dependence of -meson production at mid-rapidity in Au + Au collisions with $sqrt {^{s}NN}=200 GeV$. Comparison with the proton and anti-proton spectra reveal similar shapes, as expected for soft production described by hydrodynamics. However, the absolute yields show a different centrality dependence. The nuclear modification factors for $\phi$ are similar to those of pions, rather than (anti)protons that have similar mass. At intermediate , baryon/meson effects seem to be more important than the mass effects, in support of recombination models.
The PHENIX experiment measured J/\(\psi\) production in pp, d + Au and Au + Au reactions at \(\sqrt{s_{NN}}\) = 200 GeV over a wide range of rapidity and transverse momentum. The nuclear modification ...factor obtained by comparing the d + Au and pp cross sections as a function of rapidity, is consistent with shadowing of the gluon distribution functions. J/\(\psi\) production in Au + Au collisions was compared to the production in pp collisions and it was found to be inconsistent with models that predict strong enhancement relative to binary collision scaling.
Transverse momentum $\P_{T}$ spectra measured by the PHENIX experiment at RHIC in Au + Au, d + Au and pp collisions at $\sqrt {^S{NN}} = 200 GeV$ and in Au + Au collisions at $\sqrt {^S{NN}} = 62.4 ...GeV$ are presented. A suppression of the yield of high $\P_{T}$ hadrons in central Au + Au collisions by a factor 4-5 at $\P_{T}>5$ is found relative to the pp reference scaled by the nuclear overlap function $(\T_{AB})$ . In contrast, direct photons are not suppressed in central Au + Au collisions and no suppression of high $\P_{T}$ particles can be seen in d + Au collisions. This leads to the conclusion that the dense medium formed in central Au + Au collisions is responsible for the suppression.
Heavy flavor production in PHENIX Drapier, O
European Physical Journal C: Particles and Fields,
08/2005, Letnik:
43, Številka:
1-4
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The PHENIX experiment at RHIC measured single electron spectra in p + p, d + Au and Au + Au collisions at \(\sqrt{s_{NN}} = 200\) GeV, and in Au + Au collisions at \(\sqrt{s_{NN}} = 62.4\) GeV. In ...these spectra, electrons from semi-leptonic decays of charmed particles are the dominant contribution after subtraction of all 'photonic' sources (photon conversions, Dalitz decays, decays of light vector mesons). The p + p open charm production cross-section is found to be in good agreement with pQCD NLO calculations. The shape of the distributions obtained for p + p interactions is compared with those observed for nucleus-nucleus collisions. From p + p to d + Au and Au + Au interactions, open charm production is found to scale with the number of binary collisions \(N_{\rm coll}\). Au + Au data at \(\sqrt{s_{NN}} = 62.4\) GeV is compatible with the ISR p + p results scaled by \(N_{\rm coll}\). The elliptic flow parameter v2 of heavy flavor electrons has also been measured, and is found to be non-zero in the intermediate pT range.
We report on the development of a liquid-xenon time-projection chamber, designed to validate a new medical imaging concept named ¿3¿ imaging¿. The advantages of detection gamma-induced scintillation ...light with a gaseous photomultiplier (GPM) operating in cryogenic mode are discussed; first results are presented.
The ALICE muon spectrometer will be employed to measure the production of vector mesons in Pb-Pb collisions. In this paper we show some results concerning a test of an ALICE tracking chamber ...prototype. Performance such as resolution and efficiency as a function of high voltage are reported.
