50 research outputs found
A new measurement of J/psi suppression in Pb-Pb collisions at 158 GeV per nucleon
We present a new measurement of J/psi production in Pb-Pb collisions at 158
GeV/nucleon, from the data sample collected in year 2000 by the NA50
Collaboration, under improved experimental conditions with respect to previous
years. With the target system placed in vacuum, the setup was better adapted to
study, in particular, the most peripheral nuclear collisions with unprecedented
accuracy. The analysis of this data sample shows that the (J/psi)/Drell-Yan
cross-sections ratio measured in the most peripheral Pb-Pb interactions is in
good agreement with the nuclear absorption pattern extrapolated from the
studies of proton-nucleus collisions. Furthermore, this new measurement
confirms our previous observation that the (J/psi)/Drell-Yan cross-sections
ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb
collisions and that this ratio persistently decreases up to the most central
collisions.Comment: 19 pages, 10 figures. Submitted to Eur. Phys. J.
Centrality Behaviour of J/ Production in Na50
The J/ production in 158 A GeV Pb-Pb interactions is studied, in the
dimuon decay channel, as a function of centrality, as measured with the
electromagnetic or with the very forward calorimeters. After a first sharp
variation at mid centrality, both patterns continue to fall down and exhibit a
curvature change at high centrality values. This trend excludes any
conventional hadronic model and is in agreement with a deconfined quark-gluon
phase scenario. We report also preliminary results on the measured charged
multiplicity, as given by a dedicated detector.Comment: 5 pages, 7 figures (in eps) talk given at XXXI International
Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China URL
http://ismd31.ccnu.edu.cn
The onset of the anomalous J/ suppression in Pb-Pb collisions at the CERN SPS
The suppression observed by the NA50 experiment is one of the most striking signatures for quark gluon plasma formation in Pb-Pb collisions at 158 AGeV. The production has been studied as a function of the centrality of the collision estimated via the forward energy EZDC released in a zero degree calorimeter (ZDC). The study of the correlation between the number of participant nucleons in the collisions, Npart, and EZDC allows to check whether the suppression pattern vs. EZDC is compatible with a sudden suppression mechanism expressed as a function of Npart
Emerging Themes and Future Directions of Multi-Sector Nexus Research and Implementation
Water, energy, and food are all essential components of human societies. Collectively, their respective resource systems are interconnected in what is called the ânexusâ. There is growing consensus that a holistic understanding of the interdependencies and trade-offs between these sectors and other related systems is critical to solving many of the global challenges they present. While nexus research has grown exponentially since 2011, there is no unified, overarching approach, and the implementation of concepts remains hampered by the lack of clear case studies. Here, we present the results of a collaborative thought exercise involving 75 scientists and summarize them into 10 key recommendations covering: the most critical nexus issues of today, emerging themes, and where future efforts should be directed. We conclude that a nexus community of practice to promote open communication among researchers, to maintain and share standardized datasets, and to develop applied case studies will facilitate transparent comparisons of models and encourage the adoption of nexus approaches in practice
Quasi-static consideration of high-frequency modes for more efficient flexible multibody simulations
Transverse momentum dependence of charmonium suppression in Pb-Pb collisions at the CERN SPS
PHASE, NA50Charmonium suppression in Pb-Pb collisions at 158 GeV/c per nucleon is investigated in detail with the study of the transverse momentum distributions of J/Ï as a function of the centrality of the collision. It is shown that the observed J/Ï suppression in Pb-Pb interactions is particularly significant mainly at low transverse momentum where it strongly depends on centrality. For peripheral Pb-Pb collisions, the transverse momentum dependence of the J/Ï cross section is, as a function of centrality, qualitatively similar to the dependence observed in p-A and S-U collisions. Comparing peripheral and central Pb-Pb collisions, the data show a relative suppression in the whole pT range although its amplitude significantly decreases with increasing pT and becomes almost pT independent for the highest pT values
Charmonia Production at the CERN/SPS
4 pages, 5 figures, XXXXth Rencontres de Moriond conference - NA50 EIWe present the final results of experiment NA50 on charmonia production in Pb-Pb interactions at 158 A GeV. A strong increasing suppression is observed with increasing centrality, for both the jpsi and psiprime resonances. We also present new developments regarding the jpsi and psiprime normal nuclear absorption determinations deduced from proton-nucleus data only. Their comparison with Pb-Pb results allows us to conclude that the jpsi anomalous suppression sets in at mid-centralities while the S-U results show a reasonable agreement with the p-A behavior. The psiprime suffers a significantly stronger suppression already in S-U interactions, which continuously increases in the Pb-Pb system, and is completely incompatible with the expected behavior deduced from p-A collisions