1,402 research outputs found
Representation and usage of knowledge for initialization of accelerator control equipment
A knowledge based application, called SETUP, to initialize and diagnose the CERN/PS accelerators' control equipment is described. The object model and the general features of control algorithms are presented, together with their relation to the knowledge description of the setting up of the system. The different ways of the integration of the SETUP in the control system are outlined
Large Angle Hadron Correlations from Medium-Induced Gluon Radiation
Final state medium-induced gluon radiation in ultradense nuclear matter is
examined and shown to favor large angle emission when compared to vacuum
bremsstrahlung due to the suppression of collinear gluons. Perturbative
expression for the contribution of its hadronic fragments to the back-to-back
particle correlations is derived. It is found that in the limit of large jet
energy loss gluon radiation determines the yield and angular distribution of |
Delta phi | > Pi/2 di-hadrons to transverse momenta pT2 of the associated
particles. Clear transition from enhancement to suppression of the away-side
hadron correlations is established at moderate pT2 and its experimentally
accessible features are predicted versus the trigger particle momentum pT1.Comment: 5 pages, 3 figures. Figures 1 and 2 and some of the text revised.
Footnote added. As published in Phys. Lett.
Adatom diffusion on vicinal surfaces with permeable steps
We study the behavior of single atoms on an infinite vicinal surface assuming
certain degree of step permeability. Assuming complete lack of re-evaporation
an ruling out nucleation the atoms will inevitably join kink sites at the steps
but can do many attempts before that. Increasing the probability of step
permeability or the kink spacing lead to increase of the number of steps
crossed before incorporation of the atoms into kink sites. The asymmetry of the
attachment-detachment kinetics (Ehrlich-Schwoebel effect) suppresses the step
permeability and completely eliminates it in the extreme case of infinite
Ehrlich-Schwoebel barrier. The average number of permeability events per atom
scales with the average kink spacing. A negligibly small drift of the adatoms
in a direction perpendicular to the steps leads to a significant asymmetry of
the distribution of the permeability events the atoms thus visiting more
distant steps in the direction of the drift.Comment: 12 pages, 6 figure
Jet tomography
I summarize the recent advances in jet tomographic studies of cold and hot
nuclear matter based on perturbative QCD calculations of medium-induced gluon
bremsstrahlung. Quantitative applications to ultrarelativistic heavy ion
reactions at RHIC indicate the creation of a deconfined state of QCD with
initial energy density on the order of 100 times cold nuclear matter density.Comment: Plenary talk given at the seventeenth international conference on
Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004). 8 pages,
12 figures. Updated references, updated Table
Semi-Hard Scattering Unraveled from Collective Dynamics by Two-Pion Azimuthal Correlations in 158 A GeV/c Pb + Au Collisions
Elliptic flow and two-particle azimuthal correlations of charged hadrons and
high- pions ( 1 GeV/) have been measured close to mid-rapidity in
158A GeV/ Pb+Au collisions by the CERES experiment. Elliptic flow ()
rises linearly with to a value of about 10% at 2 GeV/. Beyond
1.5 GeV/, the slope decreases considerably, possibly indicating
a saturation of at high . Two-pion azimuthal anisotropies for
1.2 GeV/ exceed the elliptic flow values by about 60% in mid-central
collisions. These non-flow contributions are attributed to near-side and
back-to-back jet-like correlations, the latter exhibiting centrality dependent
broadening.Comment: Submitted to Phys. Rev. Letters, 4 pages, 5 figure
STUDY OF IMMUNE GENETIC RISK FACTORS OF ARTERIAL HYPERTENSION IN NATIVE AND NON-NATIVE POPULATION OF ALTAY REPUBLIC
There had been 935 people examined native to Turochaksky district of the Altai Republic (663 — indigenous people (Tubalars) and 272 — non-indigenous population) so as to identify the proportion of population with hypertension, assessment of risk factors and genetic predisposition to the disease according to the blood systems such as ABO, Rh, MN, P and Kell. The proportion of people with hypertension in the Altai Republic was 38.6 % among Tubalars and 40.8 % among non-indigenous population. The high body mass index (BMI) — (Quetelet index) values and. index: waist / hip and. waist circumference are associated, with risk of hypertension, for both ethnic groups, but only Tubalars have such risk factors as smoking and salt abuse. There had been revealed some ethnic differences in the distribution for such systems as blood group Rh factor, and MN. The indigenous ethnic group is marked with a risk of hypertension for the people with Rh(-) blood group, positive associative connection with the disease for those with the phenotype of MN and the resistance for the persons with the blood group Rh(+) and. the phenotype of NN
First Observation of the Doubly Charmed Baryon Xi_cc^+
We observe a signal for the doubly charmed baryon Xi_cc^+ in the charged
decay mode Xi_cc^+ --> Lambda_c^+ K- pi+ in data from SELEX, the charm
hadro-production experiment at Fermilab. We observe an excess of 15.9 events
over an expected background of 6.1 +/- 0.5 events, a statistical significance
of 6.3sigma. The observed mass of this state is (3519 +/- 1) MeV/c^2. The
Gaussian mass width of this state is 3MeV/c^2, consistent with resolution; its
lifetime is less than 33fsec at 90% confidence.Comment: 5 pages, 3 figures, accepted for publication in Physical Review
Letter
Lambda production in 40 A GeV/c Pb-Au collisions
During the 1999 lead run, CERES has measured hadron and electron-pair
production at 40 A GeV/c beam momentum with the spectrometer upgraded by the
addition of a radial TPC. Here the analysis of lambda and antilambda will be
presented.Comment: 8 pages, 8 figures. 6th International Conference on Strange Quarks in
Matter, Frankfurt 200
First Measurement of pi e -> pi e gamma Pion Virtual Compton Scattering
Pion Virtual Compton Scattering (VCS) via the reaction pi e --> pi e gamma
was observed in the Fermilab E781 SELEX experiment. SELEX used a 600 GeV/c pi-
beam incident on target atomic electrons, detecting the incident pi- and the
final state pi-, electron and gamma. Theoretical predictions based on chiral
perturbation theory are incorporated into a Monte Carlo simulation of the
experiment and are compared to the data. The number of reconstructed events (9)
and their distribution with respect to the kinematic variables (for the
kinematic region studied) are in reasonable accord with the predictions. The
corresponding pi- VCS experimental cross section is sigma=38.8+-13 nb, in
agreement with the theoretical expectation sigma=34.7 nb.Comment: 10 pages, 12 figures, 4 tables, 25 references, SELEX home page is
http://fn781a.fnal.gov/, revised July 21, 2002 in response to journal referee
Comment
First observation of a narrow charm-strange meson DsJ(2632) -> Ds eta and D0 K+
We report the first observation of a charm-strange meson DsJ(2632) at a mass
of 2632.6+/-1.6 MeV/c^2 in data from SELEX, the charm hadro-production
experiment E781 at Fermilab. This state is seen in two decay modes, Ds eta and
D0 K+. In the Ds eta decay mode we observe an excess of 49.3 events with a
significance of 7.2sigma at a mass of 2635.9+/-2.9 MeV/c^2. There is a
corresponding peak of 14 events with a significance of 5.3sigma at 2631.5+/-1.9
MeV/c^2 in the decay mode D0 K+. The decay width of this state is <17 MeV/c^2
at 90% confidence level. The relative branching ratio Gamma(D0K+)/Gamma(Dseta)
is 0.16+/-0.06. The mechanism which keeps this state narrow is unclear. Its
decay pattern is also unusual, being dominated by the Ds eta decay mode.Comment: 5 pages, 3 included eps figures. v2 as accepted for publication by
PR
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