1,796 research outputs found
System size and beam energy dependence of azimuthal anisotropy from PHENIX
We present azimuthal anisotropy measurements in Au+Au and Cu+Cu collisions at
= 62.4 and 200 GeV. Comparison between reaction plane and
cumulant measurements in Au+Au collisions at = 200 GeV
show that non-flow contributions, originating mainly from jets, influence the
extracted for 3.5 GeV/c. Number of constituent quark
(NCQ) scaling of , when studied as a function of transverse kinetic energy
, is seen to hold for Au+Au collisions at = 62.4 and 200
GeV and for Cu+Cu collisions at = 200 GeV for
1 GeV/c. Differential hexadecupole flow seems to exhibit
scaling with integral for centrality 40% as has been observed for
differential .Comment: 4 pages, 3 figures, Proceedings of the QM2008 Conference, Jaipur,
India February 4-10 200
Measurements of Cold Nuclear Matter Effects on J/psi in the PHENIX Experiment via Deuteron-Gold Collisions
A new calculation of R_{dAu} has been performed using the 2003 d+Au data and
the higher-statistics 2005 p+p data. These nuclear modification factors are
compared to calculations using nuclear-modified PDFs and a J/psi breakup cross
section is extracted. These values are then used to project the cold nuclear
matter effects in Au+Au collisions. Additionally, a more data-driven projection
is performed.Comment: 4 pages, 6 figures, proceedings for Quark Matter 200
Measurement of charm and bottom production in p+p collisions at = 200 GeV at RHIC-PHENIX
RHIC-PHENIX has observed a large suppression pattern and azimuthal anisotropy
of non-photonic electron at mid-rapidity () in Au+Au
collisions at GeV. To understand these results and the
interaction of heavy quarks in the hot and dense medium, experimental
determination of production ratio of charm over bottom is one of the most
important topics, since the behavior of bottom may differ from charm in the
medium. We measured the ratio of charm over bottom and total cross section of
bottom via partial reconstruction of De K decay in p+p
collisions at GeV. Total cross sections of charm and bottom
were also measured via di-electron continuum in p+p collisions at GeV.Comment: 4pages, 4figures,coferenc
Forlænget kælvningsinterval - kan være en fordelagtig produktionsstrategi
En forlængelse af laktationsperioden og dermed kælvningsintervallet til 18 måneder giver mulighed for øget andel af grovfoder i rationen. Det skyldes, at der bliver forholdsvis færre dage i tidlig laktation, hvor tildelingen af koncentreret foder er størst. Et længere kælvningsinterval betyder endvidere færre golddage per årsko, idet antal golddage per laktation var uændret. En forlængelse af kælvningsintervallet betød, at laktationsydelsen steg fra 7.656 til 11.516 kg EKM. Omregnet til ydelse per årsko giver det 7.635 versus 8.006 kg EKM ved det forlængede kælvningsinterval, altså en stigning på 371 kg EKM sammenlignet med et traditionelt kælvningsinterval. Et normalt foderniveau er en forudsætning for at opnå denne ydelsesstigning ved at forlænge kælvningsintervallet, idet der ikke blev opnået tilsvarende resultater ved et lavt foderniveau
Koens reaktion på forskelle i planlagt kælvningsinterval og energiforsyning
Et længere kælvningsinterval betyder færre golddage samtidig med, at ydelsen i starten af laktationen tilsyneladende kan øges, således at der opnås mindst samme ydelse per årsko. Det kræver imidlertid et højt foderniveau, idet årsydelsen falder mere ved det lange kælvningsinterval end ved normalt kælvningsinterval, når foderniveauet reduceres
Measurements of heavy quark production via single leptons at PHENIX
The measurement of single leptons from the semi-leptonic decay of
heavy-flavor hadrons has long been a means for studying heavy-quark production.
PHENIX has measured single muons in pp collisions at forward rapidity and
single electrons in both pp and AuAu collisions at mid-rapidity at
sqrt(s_NN)=200 GeV. The most recent PHENIX single lepton results are presented
in the context of state-of-the-art pQCD calculations. An updated azimuthal
anisotropy, v2(pT), measurement for heavy-flavor single electrons in AuAu
collisions is also presented.Comment: 4 pages, 4 figures, presented at the 19th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2008", Jaipur,
India, February 4-10, 200
Age of oils in West Greenland: was there a Mesozoic seaway between Greenland and Canada?
For many years the existence of an oil-prone source rock off West Greenland was challenged by industry. But since 1992 when active oil seeps were found onshore West Greenland on the Nuussuaq peninsula (Fig. 1; Christiansen et al. 1996; Bojesen-Koefoed et al. 1999), the question has changed focus to the age, distribution and potential of the source rock. Five different oils – each with their own characteristics – have been reported by the Geological Survey of Denmark and Greenland (GEUS). One of these, a typical marine shalederived oil with a possible regional distribution, is known as the Itilli oil. Geochemical analysis suggests that it may have been generated from Cenomanian–Turonian age marine shales, equivalent to prolific source rocks known from Ellesmere Island, Nunavut, Canada. Three of the other oils were generated from deltaic source rocks of Albian, Campanian and Paleocene ages, while one is of unknown origin (Bojesen-Koefoed et al. 1999). The presence of a regional marine source rock is important to petroleum exploration; GEUS has therefore investigated the possible existence of Mesozoic, in particular Cenomanian–Turonian, petroleum source rocks in West Greenland offshore areas. Since sediments older than the Santonian are not known from any of the six wells drilled offshore West Greenland (Fig. 1), assessment of oil-prone source rocks in older sedimentary successions must rely on circumstantial evidence offered by oil chemistry data and analogy studies. Petroleum in quantities amenable to chemical analysis has so far not been recovered from offshore. However, oilbearing fluid inclusions are known from the Ikermiut-1 well (unpublished data 2001, Phillips Petroleum and GEUS), a gas-kick was recorded during drilling of the Kangâmiut-1 well (Bate 1997), and seismic data indicate hydrocarbons in many areas (cross-cutting reflectors, bright spots, smearing of seismic). Petroleum exploration offshore West Greenland suffered for many years under the misconception that oceanic crust covered vast areas, rendering the region unattractive. However, the presence of thick sedimentary successions and rotated fault blocks in Cretaceous basins have been demonstrated to be present in areas previously believed to be underlain by Cretaceous–Tertiary oceanic crust (cf. Chalmers & Pulvertaft 2001). New high-quality seismic data, acquired by the seismic company TGS-NOPEC over recent years, combined with gravimetric data, have further demonstrated the presence of deep basins containing thick sedimentary successions in other areas (e.g. Christiansen et al. 2002). Despite the progress made over the past few years, the geological evolution of the Davis Strait region in general remains poorly understood, but new data on oil chemistry may shed some light on the history of this region
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