3,079 research outputs found
Probe station for testing of ALICE silicon drift detectors
No full textLarge area, 7.25 cm multiplied by 8.76 cm silicon drift detectors have been developed and are in production for the ALICE experiment at LHC. An active area of the detector of more than 50 cm**2 imposes high demands on the quality of processing and raw material. Automated testing procedures have been developed to test detectors before mounting them on the ladders. Probe stations for ALICE SDD testing were designed and built at INFN, Trieste and Ohio State University (OSU). Testing procedures, detector selection criteria and some details of the OSU probe station design are discussed
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Silicon drift chamber studies for the RHIC STAR experiment. Progress report, June 1, 1993--April 30, 1994
No full textIn the last year, the OSU group has made progress in all three of the areas in which we have taken our main responsibility for the SVT: (A) design of STAR SDC prototypes, (B) detector testing and radiation damage studies and (C) Monte Carlo studies to determining the feasibility of using the SVT for boson interferometry measurements. These three areas will now be discussed in this report
Hanbury-Brown-Twiss interferometry within the UrQMD transport approach
No full textIn this thesis, Hanbury-Brown-Twiss (HBT) interferometry is used together with the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) to analyse the time and space structure of heavy-ion collisions.
The first chapter after the introduction gives an overview of the different types of models used in the field of heavy-ion collisions and a introduction of the UrQMD model in more detail. The next chapter explains the basics of Hanbury-Brown-Twiss correlations, including azimuthally sensitive HBT (asHBT).
Results section:
4. Charged Multiplicities from UrQMD
5. Formation time via HBT from pp collisions at LHC
6. HBT analysis of Pb+Pb collisions at LHC energies
7. HBT scaling with particle multiplicity
8. Compressibility from event-by-event HBT
9. Tilt in non-central collisions
10. Shape analysis of strongly-interacting systems
11. Measuring a twisted emission geometry
This thesis covers the standard integrated HBT analyses, extracting the Pratt-Bertsch radii, at LHC energies. The analyses at these energies showed a too soft expansion in UrQMD probably related to the absence of a partonic phase in UrQMD. The most promising results in this thesis at these energies are the restriction of the formation time to a value smaller than 0.8 fm/c and furthermore, the results from the asHBT analyses. In simulations of non-central heavy-ion collisions at energies of Elab= 6, 8 and 30 AGeV the validity of the formulae to calculate the tilt angle via asHBT has been checked numerically, even for the case of non-Gaussian, flowing sources. On this basis has been developed and test in the course of this thesis that allows to measure a scale dependent tilt angle experimentally. The signal should be strongest at FAIR energies.In dieser Arbeit wird Hanbury-Brown-Twiss (HBT) Interferometrie benutzt um im Rahmen des Models „Ultrarelativistische Quanten Molekular Dynamik“ (UrQMD) die Raum und Zeit Geometrie von Schwerionen Kollisionen zu untersuchen.
Das erste Kapitel nach der Einleitung gibt einen Überblicke über die verschiedenen Sorten von Modellen, die im Feld zur Beschreibung von Schwerionen Kollisionen genutzt werden. Dabei wird ein besonderer Fokus auf die Beschreibung des UrQMD Modelles gesetzt da dieses für die Untersuchungen in dieser Arbeit verwendet wurde.
Das nächste Kapitel gibt eine Einführung in die Grundlagen der HBT Korrelationen und enthält auch einen Abschnitt über azimuthal sensitives HBT (asHBT), welches für diese Arbeit wichtig ist.
Resultat Kapitel:
4. Charged Multiplicities from UrQMD
5. Formation time via HBT from pp collisions at LHC
6. HBT analysis of Pb+Pb collisions at LHC energies
7. HBT scaling with particle multiplicity
8. Compressibility from event-by-event HBT
9. Tilt in non-central collisions
10. Shape analysis of strongly-interacting systems
11. Measuring a twisted emission geometry
Die Resultat Kapitel enthalten die Standard Analysen zu den HBT bei LHC Energien. Dabei zeigt sich, dass die Expansion des Mediums in UrQMD zu weich ist. Dies hängt wahrscheinlich damit zusammen, dass in UrQMD keine partonische Wechselwirkungsphase vorhanden ist. Die interessantesten Ergebnisse sind zum einen die Beschränkung der Formationszeit auf einen Wert kleiner als 0.8 fm/c und zum anderen die Resultate der asHBT Analysen. In der Simulation von semizentralen Kollisionen bei Energien von Elab= 6, 8 und 30 AGeV wurde die Anwendbarkeit der Formel zur Berechnung des Drehungswinkels im Falle von nicht-Gaußschen Quellen mit Fluss numerisch nachgewiesen. Auf dieser Grundlage haben wir ein Verfahren entwickelt und getestet, das es erlaubt einen skalenabhängigen Drehungswinkel experimentell zu messen. Das Signal für diesen Drehungswinkel sollte bei FAIR Energien am größten sein
ГУМАНИЗМ И ГУМАНИЗАЦИЯ СОВРЕМЕННОГО ОБРАЗОВАТЕЛЬНОГО ПРОСТРАНСТВА РОССИИ
No full textThe paper is aimed at analyzing the problem of education as factor of humanization of society; it reveals the criterion of humanity and humanization of social development. The author supposes it is necessary to consider humanism as a value of a person; this is a valuable core of the Russian cultural tradition. The Russian philosophical thought is deeply humanic as it focuses on a person. his happiness, sense of his life and objective reality. The Russian philosophers as Berdyaev N., Florensky P., Karelin A. criticized humanism for being the basis of European civilization. Otherwise, the Russian philosophy objected to the Soviet character of European humanism, its Eurocentrism and anthropocentrism as it became a contradiction to the nature of Christian Russian philosophy. Humanism in its global meaning is a proclamation of human inherent value that makes a valuable core of Russian cultural tradition. The modern pedagogical space concentrates on the global crisis and necessity to search for society with humanistic focus. This search results in the educational system as two components of “Humanistic triad” i.e. science and art appeared in problematic situation. The educational system had been unchangeable for a long time and responded to the social challenges. However, the latest reforms demonstrate the weakness of attempts to change the educational system by means of liberal rationalization tradition. The paper reveals the main tendencies in education and its development, which can appear to be the instrument of Russian society humanization
Charm fragmentation fractions and c-cbar cross section in p–Pb collisions at sqrt(sNN)=5.02 TeV
No full textThe total charm-quark production cross section per unit of rapidity dσ (cc)/dy, and the fragmentation fractions of charm quarks to different charm-hadron species f (c → hc), are measured for the first time in p–Pb collisions at √sNN = 5.02 TeV at midrapidity (−0.96 < y < 0.04 in the centre-of-mass frame) using data collected by ALICE at the CERN LHC.
The results are obtained based on all the available measurements of prompt production of ground-state charm-hadron species: D0 , D+, D+s , and J/ψ mesons, and Lambda+c and Csi0c baryons. The resulting cross section is dσ (cc)/dy = 219.6 ± 6.3 (stat.) +10.5−11.8 (syst.) +8.3−2.9 (extr.) ± 5.4 (BR) ±4.6 (lumi.)±19.5 (rapidity shape)+15.0 (Omega0c ) mb, which is consistent with a binary scaling of pQCD calculations from pp collisions. The measured fragmentation fractions are compatible with those measured in pp collisions at √s = 5.02 and 13 TeV, showing an increase in the relative production rates of charm baryons with respect to charm mesons in pp and
p–Pb collisions compared with e+e− and e−p collisions. The pT -integrated nuclear modification factor of charm quarks, RpPb(cc) = 0.91 ± 0.04 (stat.)+0.08−0.09 (syst.)+0.05−0.03 (extr.) ±0.03 (lumi.), is found to be consistent with unity and with theoretical predictions including nuclear modifications of the
parton distribution functions
First measurement of Xi(0)(c) production in pp collisions at root s=7 TeV
No full textThe production of the charm-strange baryon Xi(0)(c) is measured for the first time at the LHC via its semileptonic decay into e(+) Xi(-) nu(e) in ppcollisions at root s = 7 TeV with the ALICE detector. The transverse momentum ( p(T)) differential cross section multiplied by the branching ratio is presented in the interval 1 < p(T)< 8 GeV/c at mid-rapidity, vertical bar y vertical bar < 0.5. The transverse momentum dependence of the Xi(0)(c) baryon production relative to the D-0 meson production is compared to predictions of event generators with various tunes of the hadronisation mechanism, which are found to underestimate the measured cross-section ratio. (C) 2018 The Author(s). Published by Elsevier B.V
Measurement of the Cross Sections of Ξ0 c and Ξ+ c Baryons and of the Branching-Fraction Ratio BRðΞ0 c → Ξ− e + νeÞ=BRðΞ0 c → Ξ− π + Þ in pp Collisions at ffiffi s p = 13 TeV
No full textThe pT-differential cross sections of prompt charm-strange baryons Ξ0c and Ξ+c were measured at midrapidity (|y|<0.5) in proton-proton (pp) collisions at a center-of-mass energy √s=13 TeV with the ALICE detector at the LHC. The Ξ0c baryon was reconstructed via both the semileptonic decay (Ξ−e+νe) and the hadronic decay (Ξ−π+) channels. The Ξ+c baryon was reconstructed via the hadronic decay (Ξ−π+π+) channel. The branching-fraction ratio BR(Ξ0c→Ξ−e+νe)/BR(Ξ0c→Ξ−π+)=1.38±0.14(stat)±0.22(syst) was measured with a total uncertainty reduced by a factor of about 3 with respect to the current world average reported by the Particle Data Group. The transverse momentum (pT) dependence of the Ξ0c- and Ξ+c-baryon production relative to the D0 meson and to the Σ0,+,++c- and Λ+c-baryon production are reported. The baryon-to-meson ratio increases toward low pT up to a value of approximately 0.3. The measurements are compared with various models that take different hadronization mechanisms into consideration. The results provide stringent constraints to these theoretical calculations and additional evidence that different processes are involved in charm hadronization in electron-positron (e+e−) and hadronic collisions
Measurement of the production cross section of prompt Xi(0)(c) baryons at midrapidity in pp collisions at root s=5.02 TeV
No full textTwo-particle Azimuthal correlations are measured with the ALICE apparatus in pp collisions at s=13 TeV to explore strangeness- and multiplicity-related effects in the fragmentation of jets and the transition regime between bulk and hard production, probed with the condition that a strange meson (KS0) or baryon (Λ) with transverse momentum pT> 3 GeV/c is produced. Azimuthal correlations between kaons or Λ hyperons with other hadrons are presented at midrapidity for a broad range of the trigger (3<20 GeV/c) and associated particle pT (1 GeV/
Particle production in central Pb + Pb collisions at 158 AGeV/c
No full textThe NA44 experiment has measured single-particle inclusive spectra for charged pions, kaons, and protons as a function of transverse mass near midrapidity in 158A GeV/c Pb+Pb collisions. From the particle mass dependence of the observed m/sub T/ distributions, we are able to deduce a value of about 120 MeV for the temperature at thermal freeze-out. From the observed ratios of the rapidity densities, we find values of the chemical potentials for light and strange quarks and a chemical freeze-out temperature of approximately 140 MeV. (34 refs).The NA44 experiment has measured single particle inclusive spectra for charged pions, kaons, and protons as a function of transverse mass near mid-rapidity in 158 A GeV/ Pb+Pb collisions. From the particle mass dependence of the observed distributions, we are able to deduce a value of about 120 MeV for the temperature at thermal freeze-out. From the observed ratios of the rapidity densities, we find values of the chemical potentials for light and strange quarks and a chemical freeze-out temperature of approximately 140 MeV
Measurement of the production cross section of prompt baryons in p–Pb collisions at TeV
No full textThe transverse momentum (pT) differential production cross section of the promptly produced charm strange
baryon Csi_0c (and its charge conjugate anti_Csi_0c) is measured at midrapidity via its hadronic decay into π+ Sigma-
in p–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision √sNN = 5.02 TeV with the ALICE detector at the LHC.
The Csi_0c nuclear modification factor (RpPb), calculated
from the cross sections in pp and p–Pb collisions, is
presented and compared with the RpPb of
+c
baryons. The
ratios between the pT-differential production cross section of
0c
baryons and those of D0 mesons and
+c
baryons are also
reported and compared with results at forward and backward
rapidity from the LHCb Collaboration. Themeasurements of
the production cross section of prompt 0c
baryons are compared
with a model based on perturbative QCD calculations
of charm-quark production cross sections, which includes
only cold nuclear matter effects in p–Pb collisions, and underestimates
the measurement by a factor of about 50. This discrepancy
is reduced when the data is compared with a model
that includes string formation beyond leading-colour approximation
or in which hadronisation is implemented via quark
coalescence. The pT-integrated cross section of prompt
0c
-baryon production at midrapidity extrapolated down to
pT = 0 is also reported. These measurements offer insights
and constraints for theoretical calculations of the hadronisation
process. Additionally, they provide inputs for the calculation
of the charm production cross section in p–Pb collisions
at midrapidity
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