35 research outputs found
Eliminating fluctuations in fixed-target heavy-ion experiments
Experimental and theoretical studies of fluctuations in nucleus-nucleus
interactions at high energies have started to play a major role in
understanding of the concept of strong interactions. The elaborated procedures
have been developed to disentangle different processes happening during
nucleus-nucleus collisions. The fluctuations caused by a variation of the
number of nucleons which participated in a collision are frequently considered
the unwanted one. The methods to eliminate these fluctuations in fixed-target
experiments are reviewed and tested. They can be of key importance in the
following ongoing fixed-target heavy-ion experiments: NA61/SHINE at the CERN
SPS, STAR-FT at the BNL RHIC, BM\@N at JINR Nuclotron, HADES at the GSI SIS18
and in future experiments such as NA60+ at the CERN SPS, CBM at the FAIR
SIS100, JHITS at J-PARC-HI MR.Comment: Updated list of grant
Antideuteron and deuteron production in mid-central Pb+Pb collisions at 158 GeV
Production of deuterons and antideuterons was studied by the NA49 experiment
in the 23.5% most central Pb+Pb collisions at the top SPS energy of
=17.3 GeV. Invariant yields for and were measured
as a function of centrality in the center-of-mass rapidity range .
Results for together with previously published
measurements are discussed in the context of the coalescence model. The
coalescence parameters were deduced as a function of transverse momentum
and collision centrality.Comment: 9 figure
Measurement of event-by-event transverse momentum and multiplicity fluctuations using strongly intensive measures and in nucleus-nucleus collisions at the CERN Super Proton Synchrotron
Results from the NA49 experiment at the CERN SPS are presented on
event-by-event transverse momentum and multiplicity fluctuations of charged
particles, produced at forward rapidities in central Pb+Pb interactions at beam
momenta 20, 30, 40, 80, and 158 GeV/c, as well as in systems of
different size (, C+C, Si+Si, and Pb+Pb) at 158 GeV/c. This publication
extends the previous NA49 measurements of the strongly intensive measure
by a study of the recently proposed strongly intensive measures of
fluctuations and . In the explored kinematic
region transverse momentum and multiplicity fluctuations show no significant
energy dependence in the SPS energy range. However, a remarkable system size
dependence is observed for both and , with the
largest values measured in peripheral Pb+Pb interactions. The results are
compared with NA61/SHINE measurements in collisions, as well as with
predictions of the UrQMD and EPOS models.Comment: 12 pages, 14 figures, to be submitted to PR
Multiplicity and transverse momentum fluctuations in inelastic proton-proton interactions at the CERN Super Proton Synchrotron
Measurements of multiplicity and transverse momentum fluctuations of charged
particles were performed in inelastic p+p interactions at 20, 31, 40, 80 and
158 GeV/c beam momentum. Results for the scaled variance of the multiplicity
distribution and for three strongly intensive measures of multiplicity and
transverse momentum fluctuations \$\Delta[P_{T},N]\$, \$\Sigma[P_{T},N]\$ and
\$\Phi_{p_T}\$ are presented. For the first time the results on fluctuations
are fully corrected for experimental biases. The results on multiplicity and
transverse momentum fluctuations significantly deviate from expectations for
the independent particle production. They also depend on charges of selected
hadrons. The string-resonance Monte Carlo models EPOS and UrQMD do not describe
the data. The scaled variance of multiplicity fluctuations is significantly
higher in inelastic p+p interactions than in central Pb+Pb collisions measured
by NA49 at the same energy per nucleon. This is in qualitative disagreement
with the predictions of the Wounded Nucleon Model. Within the statistical
framework the enhanced multiplicity fluctuations in inelastic p+p interactions
can be interpreted as due to event-by-event fluctuations of the fireball energy
and/or volume.Comment: 18 pages, 12 figure
Measurement of Production Properties of Positively Charged Kaons in Proton-Carbon Interactions at 31 GeV/c
Spectra of positively charged kaons in p+C interactions at 31 GeV/c were
measured with the NA61/SHINE spectrometer at the CERN SPS. The analysis is
based on the full set of data collected in 2007 with a graphite target with a
thickness of 4% of a nuclear interaction length. Interaction cross sections and
charged pion spectra were already measured using the same set of data. These
new measurements in combination with the published ones are required to improve
predictions of the neutrino flux for the T2K long baseline neutrino oscillation
experiment in Japan. In particular, the knowledge of kaon production is crucial
for precisely predicting the intrinsic electron neutrino component and the high
energy tail of the T2K beam. The results are presented as a function of
laboratory momentum in 2 intervals of the laboratory polar angle covering the
range from 20 up to 240 mrad. The kaon spectra are compared with predictions of
several hadron production models. Using the published pion results and the new
kaon data, the K+/\pi+ ratios are computed.Comment: 10 pages, 11 figure
Production of Λ-hyperons in inelastic p+p interactions at 158 GeV/c
Inclusive production of Λ -hyperons was measured with the large acceptance NA61/SHINE spectrometer at the CERN SPS in inelastic p+p interactions at beam momentum of 158 GeV/c . Spectra of transverse momentum and transverse mass as well as distributions of rapidity and x F are presented. The mean multiplicity was estimated to be 0.120±0.006(stat.)±0.010(sys.). The results are compared with previous measurements and predictions of the Epos , U r qmd and Fritiof models
Search for the critical point by the NA61/SHINE experiment
NA61/SHINE is a fixed target experiment operating at CERN SPS. Its main goals are to search for the critical point of stronglyinteractingmatterandtostudytheonsetofdeconfinement. Forthesegoalsascanofthetwodimensionalphase diagram (T-μB) is being performed at the SPS by measurements of hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy. In this paper the status of the search for the critical point of strongly interacting matter by the NA61/SHINE Collaboration is presented including recent results on proton intermittency, strongly intensive fluctuation observables of multiplicity and transverse momentum fluctuations. These measurements are expected to be sensitive to the correlation length and, therefore, have the ability to reveal the existence of the critical point via possible non-monotonic behavior. The new NA61/SHINE results are compared to the model predictions