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[show abstract]
[hide abstract]
ABSTRACT: New data on proton and pion production in p+C interactions from the CERN PS
and SPS accelerators are used in conjunction with other available data sets to
perform a comprehensive survey of backward hadronic cross sections. This survey
covers the complete backward hemisphere in the range of lab angles from 10 to
180 degrees, from 0.2 to 1.4 GeV/c in lab momentum and from 1 to 400 GeV/c in
projectile momentum. Using the constraints of continuity and smoothness of the
angular, momentum and energy dependences a consistent description of the
inclusive cross sections is established which allows the control of the
internal consistency of the nineteen available data sets.
10/2012;
-
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
J. Beck,
L. Betev,
H. Białkowska,
C. Blume,
M. Bogusz,
B. Boimska, [......], D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranić,
Z. Włodarczyk,
A. Wojtaszek-Szwarć,
N. G. Antoniou,
N. Davis,
F. K. Diakonos
[show abstract]
[hide abstract]
ABSTRACT: Studies of QCD suggest the existence of a critical point in the phase diagram
of strongly interacting matter. Close to this point, according to recent
theoretical investigations, the net-proton density carries the critical
fluctuations of the chiral order parameter. Using intermittency analysis in the
transverse momentum phase space of protons produced around midrapidity in the
12.5% most central C+C, Si+Si and Pb+Pb collisions at the maximum SPS energy of
158$A$ GeV we find evidence of power-law fluctuations for the Si+Si and Pb+Pb
data. The fitted power-law exponent approaches the value expected for critical
fluctuations. This suggests that the freeze-out states of these two systems are
located in the phase diagram in the neighbourhood of the chiral critical point.
08/2012;
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The Collaboration,
B. Baatar,
G. Barr,
J. Bartke,
L. Betev,
O. Chvala,
J. Dolejsi,
V. Eckardt,
H. G. Fischer,
Z. Fodor, [......],
M. Mateev,
G. Melkumov,
A. Rybicki,
N. Schmitz,
P. Seyboth,
R. Stock,
G. Tinti, D. Varga,
G. Vesztergombi,
S. Wenig
[show abstract]
[hide abstract]
ABSTRACT: The production of protons, anti-protons, neutrons, deuterons and tritons in
minimum bias p+C interactions is studied using a sample of 385 734 inelastic
events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam
momentum. The data cover a phase space area ranging from 0 to 1.9 GeV/c in
transverse momentum and in Feynman x from -0.80 to 0.95 for protons, from -0.2
to 0.4 for anti-protons and from 0.2 to 0.95 for neutrons. Existing data in the
far backward hemisphere are used to extend the coverage for protons and light
nuclear fragments into the region of intranuclear cascading. The use of
corresponding data sets obtained in hadron-proton collisions with the same
detector allows for the detailed analysis and model-independent separation of
the three principle components of hadronization in p+C interactions, namely
projectile fragmentation, target fragmentation of participant nucleons and
intranuclear cascading.
07/2012;
-
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
H. Beck,
L. Betev,
H. Bialkowska,
C. Blume,
M. Bogusz,
B. Boimska, [......],
T. Susa,
M. Szuba,
M. Utvic, D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranic,
Z. Wlodarczyk,
A. Wojtaszek-Szwarc
[show abstract]
[hide abstract]
ABSTRACT: Measurements of charged pion and kaon production are presented in centrality
selected Pb+Pb collisions at 40A GeV and 158A GeV beam energy as well as in
semi-central C+C and Si+Si interactions at 40A GeV. Transverse mass spectra,
rapidity spectra and total yields are determined as a function of centrality.
The system-size and centrality dependence of relative strangeness production in
nucleus-nucleus collisions at 40A GeV and 158A GeV beam energy are derived from
the data presented here and published data for C+C and Si+Si collisions at 158A
GeV beam energy. At both energies a steep increase with centrality is observed
for small systems followed by a weak rise or even saturation for higher
centralities. This behavior is compared to calculations using transport models
(UrQMD and HSD), a percolation model and the core-corona approach.
07/2012;
-
A. Agócs,
R. Alfaro,
G. G. Barnaföldi,
L. Boldizsár,
E. Cuautle,
G. De Cataldo,
D. Di Bari,
A. Di Mauro,
I. Dominguez,
Z. Fodor, [......],
D. Perini,
V. Peskov,
F. Piuz,
P. Podesta,
L. Serkin,
O. Sokolov,
N. Smirnov, D. Varga,
G. Volpe,
VHMPID Protocollaboration
[show abstract]
[hide abstract]
ABSTRACT: The anomalies observed at RHIC for the baryon — meson ratios have prompted a number of theoretical works on the nature of
the hadrochemistry in the hadronisation stage of the pp collisions and in the evolution of the dense system formed in heavy
ion collisions. Although the predictions differ in the theoretical approach, generally a substantial increase in the baryon
production is predicted in the range 10–30 GeV/c. We will present the possibilities of a gas ring imaging Cherenkov detector
of limited acceptance which would be able to identify track-by-track protons until 24 GeV/c for the ALICE experiment.
KeywordsBaryon–Mesons–Heavy ion collision
Indian Journal of Physics and Proceedings of the Indian Association for the Cultivation of Science -New Series- 04/2012; 84(12):1635-1639. · 0.38 Impact Factor
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Peter Seyboth,
Collaboration,
S. V. Afanasiev,
T. Anticic,
D. Barna,
J. Bartke,
R. A. Barton,
L. Betev,
H. Bialkowska,
A. Billmeier, [......], D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranic,
S. Wenig,
A. Wetzler,
I. KYoo,
J. Zaranek,
J. Zimanyi
[show abstract]
[hide abstract]
ABSTRACT: Experiment NA49 at the CERN SPS uses a large acceptance detector for a systematic study of particle yields and correlations
in nucleus-nucleus, nucleon-nucleus and nucleon-nucleon collisions. Preliminary results for Pb+Pb collisions at 40, 80 and
158 A⋅GeV beam energy shown and compared to measurements at lower and higher energies.
Pramana 04/2012; 60(4):725-737. · 0.57 Impact Factor
-
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
H. Beck,
L. Betev,
H. Białkowska,
C. Blume,
M. Bogusz,
B. Boimska, [......],
T. Susa,
M. Szuba,
M. Utvić, D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranić,
Z. Włodarczyk,
A. Wojtaszek-Szwarć
[show abstract]
[hide abstract]
ABSTRACT: Production of deuterons and antideuterons was studied by the NA49 experiment in the 23.5% most central Pb+Pb collisions at the top CERN Super Proton Synchroton (SPS) energy of √sNN=17.3 GeV. Invariant yields for d̅ and d were measured as a function of centrality in the center-of-mass rapidity range −1.2<y<−0.6. Results for d̅ (d) together with previously published p̅ (p) measurements are discussed in the context of the coalescence model. The coalescence parameters B2 were deduced as a function of transverse momentum pt and collision centrality.
Phys. Rev. C. 04/2012; 85(4).
-
[show abstract]
[hide abstract]
ABSTRACT: The angular distribution of Kr 4p photoelectrons was investigated experimentally in the photon energy range of the 3d −1 → np resonant excitations. The experimental dipole and non-dipole anisotropy parameters were determined for the spin-orbit components of the Kr 4p shell. An interference effect was observed between the direct photoionization and the resonant excitation participator Auger decay processes in the photon energy dependence of the experimental anisotropy parameters.
Journal of Physics Conference Series 01/2012; 388(2):022005.
-
A. G. Agócs,
R. Alfaro,
G. G. Barnaföldi,
R. Bellwied,
Gy. Bencze,
D. Berényi,
L. Boldizsár,
E. Cuautle,
G. De Cataldo,
D. Di Bari, [......],
S. Pochybová,
N. Smirnov,
J. Song,
A. Timmins, D. Varga,
A. Vargas,
S. Vergara,
G. Volpe,
J. Yi,
I. -K. Yoo
[show abstract]
[hide abstract]
ABSTRACT: This article presents the basic idea of VHMPID, an upgrade detector for the
ALICE experiment at LHC, CERN. The main goal of this detector is to extend the
particle identification capabilities of ALICE to give more insight into the
evolution of the hot and dense matter created in Pb-Pb collisions. Starting
from the physics motivations and working principles the challenges and current
status of development is detailed.
03/2011;
-
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
H. Beck,
L. Betev,
H. Bialkowska,
C. Blume,
M. Bogusz,
B. Boimska, [......],
T. Susa,
M. Szuba,
M. Utvic, D. Varga,
M. Vassiliou,
G. Veres,
G. Vesztergombi,
D. Vranic,
Z. Wlodarczyk,
A. Wojtaszek-Szwarc
[show abstract]
[hide abstract]
ABSTRACT: The momentum correlation between protons and lambda particles emitted from
central Pb+Pb collisions at sqrt(s_{NN}) = 17.3 GeV was studied by the NA49
experiment at the CERN SPS. A clear enhancement is observed for small relative
momenta (q_{inv} < 0.2 GeV). By fitting a theoretical model, which uses the
strong interaction between the proton and the lambda in a given pair, to the
measured data a value for the effective source size is deduced. Assuming a
static Gaussian source distribution we derive an effective radius parameter of
R_G = 3.02 \pm 0.20$(stat.)^{+0.44}_{-0.16}(syst.) fm.
03/2011;
-
T. Anticic,
B Baatar,
D Barna,
J. Bartke,
H. Beck,
L Betev,
H Białkowska,
C Blume,
M. Bogusz,
B Boimska, [......],
T Susa,
M. Szuba,
M. Utvić, D Varga,
M Vassiliou,
G I Veres,
G Vesztergombi,
D Vranić,
Z Włodarczyk,
A. Wojtaszek-Szwarc
[show abstract]
[hide abstract]
ABSTRACT: Kaons and protons carry large parts of two conserved quantities, strangeness
and baryon number. It is argued that their correlation and thus also
fluctuations are sensitive to conditions prevailing at the anticipated
parton-hadron phase boundary. Fluctuations of the $(\mathrm{K}^+ +
\mathrm{K}^-)/(\mathrm{p}+\bar{\mathrm{p}})$ and $\mathrm{K}^+/\mathrm{p}$
ratios have been measured for the first time by NA49 in central Pb+Pb
collisions at 5 SPS energies between $\sqrt{s_{NN}}$= 6.3 GeV and 17.3 GeV.
Both ratios exhibit a change of sign in $\sigma_{\mathrm{dyn}}$, a measure of
non-statistical fluctuations, around $\sqrt{s_{NN}}$ = 8 GeV. Below this
energy, $\sigma_{\mathrm{dyn}}$ is positive, indicating higher fluctuation
compared to a mixed event background sample, while for higher energies,
$\sigma_{\mathrm{dyn}}$ is negative, indicating correlated emission of kaons
and protons. The results are compared to UrQMD calculations which which give a
good description at the higher SPS energies, but fail to reproduce the
transition to positive values.
01/2011;
-
T. Anticic,
B Baatar,
D Barna,
J. Bartke,
H. Beck,
L Betev,
H Bialkowska,
C Blume,
M. Bogusz,
B Boimska, [......],
H. Strobele,
T Susa,
M. Szuba,
M. Utvic, D Varga,
M. Vassiliou G. I. Veres,
G Vesztergombi,
D Vranic,
Z Włodarczyk,
A. Wojtaszek-Szwarc
[show abstract]
[hide abstract]
ABSTRACT: The yields of (anti-)protons were measured by the NA49 Collaboration in
centrality selected Pb+Pb collisions at 40A GeV and 158A GeV. Particle
identification was obtained in the laboratory momentum range from 5 to 63 GeV/c
by the measurement of the energy loss dE/dx in the TPC detector gas. The
corresponding rapidity coverage extends 1.6 units from mid-rapidity into the
forward hemisphere. Transverse mass spectra, the rapidity dependences of the
average transverse mass, and rapidity density distributions were studied as a
function of collision centrality. The values of the average transverse mass as
well as the midrapidity yields of protons when normalized to the number of
wounded nucleons show only modest centrality dependences. In contrast, the
shape of the rapidity distribution changes significantly with collision
centrality, especially at 40A GeV. The experimental results are compared to
calculations of the HSD and UrQMD transport models.
Phys. Rev. C. 09/2010; 83(1).
-
[show abstract]
[hide abstract]
ABSTRACT: The angular distribution of the Kr 4p photoelectrons was investigated in the photon energy range of the (3d)-1→np resonant excitations. The experimental dipole (β) and nondipole (γ and δ) anisotropy parameters were determined for the spin-orbit components of the Kr 4p shell. A simple theoretical model was developed for the description of the photoionization and excitation processes. An interference effect was observed between the direct photoionization and the resonant excitation participator Auger decay processes in the photon energy dependence of the experimental anisotropy parameters.
Phys. Rev. A. 04/2010; 81(4).
-
The NA49 Collaboration,
T. Anticic,
B Baatar,
J. Bartke,
L Betev,
H Białkowska,
B Boimska,
J. Bracinik,
V. Cerny,
O Chvala, [......],
G. Melkumov,
A Rybicki,
N Schmitz,
P. Seyboth,
T Susa,
P Szymanski,
V Trubnikov, D Varga,
G Vesztergombi,
S Wenig
[show abstract]
[hide abstract]
ABSTRACT: New data on the production of charged kaons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The kaons are identified by energy loss in a large TPC tracking system. Inclusive invariant cross sections are obtained in intervals from 0 to 1.7 GeV/c in transverse momentum and from 0 to 0.5 in Feynman x. Using these data as a reference, a new evaluation of the energy dependence of kaon production, including neutral kaons, is conducted over a range from 3 GeV to p+anti-p collider energies. Comment: 106 pages, 136 figures
04/2010;
-
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
H. Beck,
L. Betev,
H. Białkowska,
C. Blume,
B. Boimska,
J. Book, [......],
V. Trubnikov,
M. Utvić, D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranić,
S. Wenig,
Z. Włodarczyk,
A. Wojtaszek
Nuclear Physics A 10/2009; 830:959-959. · 1.54 Impact Factor
-
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
H. Beck,
L. Betev,
H. Białkowska,
C. Blume,
B. Boimska,
J. Book, [......],
P. Szymanski,
M. Utvić, D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranić,
Z. Włodarczyk,
A. Wojtaszek,
I. K. Yoo
[show abstract]
[hide abstract]
ABSTRACT: Results on Λ, Λ̅ , and Ξ- production in centrality selected Pb+Pb reactions at 40A and 158A GeV and in near-central C+C and Si+Si reactions at 158A GeV are presented. Transverse mass spectra, rapidity spectra, and multiplicities in dependence of the system size are discussed. Comparisons to transport models (ultrarelativistic quantum molecular dynamics and hadron string dynamics) and to the core-corona approach are performed. Although Λ and Λ̅ production can be described by transport models reasonably well, these models do not agree with the Ξ- measurements. However, the core-corona picture fits very well the system-size dependence of Λ and Ξ-, whereas it agrees less well with the Λ̅ data.
Phys. Rev. C. 09/2009; 80(3).
-
C. Alt,
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
L. Betev,
H. Białkowska,
C. Blume,
B. Boimska,
M. Botje, [......],
P. Szymanski,
V. Trubnikov, D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranić,
A. Wetzler,
Z. Włodarczyk,
I. K. Yoo
[show abstract]
[hide abstract]
ABSTRACT: We present measurements of the energy dependence of event-by-event fluctuations in the K/π and (p+p̅ )/π multiplicity ratios in heavy-ion collisions at the CERN SPS. The particle ratio fluctuations were obtained for central Pb+Pb collisions at five collision energies, √sNN, between 6.3 and 17.3 GeV. After accounting for the effects of finite-number statistics and detector resolution, we extract the strength of nonstatistical fluctuations at each energy. For the K/π ratio, larger fluctuations than expected for independent particle production are found at all collision energies. The fluctuations in the (p+p̅ )/π ratio are smaller than expectations from independent particle production, indicating correlated pion and proton production from resonance decays. For both ratios, the deviation from purely statistical fluctuations shows an increase toward lower collision energies. The results are compared to transport model calculations, which fail to describe the energy dependence of the K/π ratio fluctuations.
Phys. Rev. C. 04/2009; 79(4).
-
NA49 Collaboration,
T. Anticic,
B Baatar,
J. Bartke,
L Betev,
H Białkowska,
C Blume,
B Boimska,
J. Bracinik,
V. Cerny, [......],
H Ströbele,
T Susa,
P Szymanski,
V Trubnikov, D Varga,
G Vesztergombi,
D Vranić,
S Wenig,
Z Włodarczyk,
A Wojtaszek
[show abstract]
[hide abstract]
ABSTRACT: New data on the production of protons, anti-protons and neutrons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The charged baryons are identified by energy loss measurement in a large TPC tracking system. Neutrons are detected in a forward hadronic calorimeter. Inclusive invariant cross sections are obtained in intervals from 0 to 1.9 GeV/c (0 to 1.5 GeV/c) in transverse momentum and from -0.05 to 0.95 (-0.05 to 0.4) in Feynman x for protons (anti-protons), respectively. pT integrated neutron cross sections are given in the interval from 0.1 to 0.9 in Feynman x. The data are compared to a wide sample of existing results in the SPS and ISR energy ranges as well as to proton and neutron measurements from HERA and RHIC. Comment: 69 pages, 72 figures
04/2009;
-
C. Alt,
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
L. Betev,
H. Białkowska,
C. Blume,
B. Boimska,
M. Botje, [......],
V. Trubnikov, D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranić,
A. Wetzler,
Z. Włodarczyk,
I. K. Yoo,
J. Zimányi
[show abstract]
[hide abstract]
ABSTRACT: ϕ meson production is studied by the NA49 Collaboration in central Pb+Pb collisions at 20A,30A,40A,80A, and 158A GeV beam energy. The data are compared with measurements at lower and higher energies and with microscopic and thermal models. The energy dependence of yields and spectral distributions is compatible with the assumption that partonic degrees of freedom set in at low SPS energies.
Phys. Rev. C. 10/2008; 78(4).
-
C. Alt,
T. Anticic,
B. Baatar,
D. Barna,
J. Bartke,
L. Betev,
H. Białkowska,
C. Blume,
B. Boimska,
M. Botje, [......], D. Varga,
M. Vassiliou,
G. I. Veres,
G. Vesztergombi,
D. Vranić,
A. Wetzler,
Z. Włodarczyk,
A. Wojtaszek,
I. K. Yoo,
J. Zimányi
[show abstract]
[hide abstract]
ABSTRACT: Results on Λ,Λ̅ ,Ξ-, and Ξ̅ + production in central Pb+Pb reactions at 20A,30A,40A,80A, and 158A GeV are presented. The energy dependence of transverse mass spectra, rapidity spectra, and multiplicities is discussed. Comparisons to string hadronic models (UrQMD and HSD) and statistical hadron gas models are shown. Although the latter provide a reasonable description of all particle yields, the first class of models fails to match the Ξ- and Ξ̅ + multiplicities.
Phys. Rev. C. 09/2008; 78(3).
