This paper reports measurements of two-pion Bose-Einstein (HBT) correlations in Be+Be collisions at a beam momentum of 150$A\,\mbox{GeV}/\textit{c}$ by the $\mbox{NA61/SHINE}$ experiment at the CERN ...SPS accelerator. The obtained momentum space correlation functions can be well described by a Lévy distributed source model. The transverse mass dependence of the Lévy source parameters is presented, and their possible theoretical interpretations are discussed. The results show that the Lévy exponent $\alpha$ is approximately constant as a function of $m_{\rm{T}}$ , and far from both the Gaussian case of $\alpha = 2$ or the conjectured value at the critical endpoint, $\alpha = 0.5$. The radius scale parameter $R$ shows a slight decrease in $m_{\rm{T}}$, which can be explained as a signature of transverse flow. Finally, an approximately constant trend of the intercept parameter $\lambda$ as a function of $m_{\rm{T}}$ was observed, different from measurement results at RHIC.
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The physics goal of the strong interaction program of the NA61/SHINE experiment at the CERN Super Proton Synchrotron (SPS) is to study the phase diagram of hadronic matter by a scan of particle ...production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents differential inclusive spectra of transverse momentum, transverse mass and rapidity of $\pi ^{-}$ mesons produced in central^{40}$Ar+^{45}$Sc collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150$A\,\text{ Ge }\text{ V }\!/\!\textit{c}$. Energy and system size dependence of parameters of these distributions – mean transverse mass, the inverse slope parameter of transverse mass spectra, width of the rapidity distribution and mean multiplicity – are presented and discussed. Furthermore, the dependence of the ratio of the mean number of produced pions to the mean number of wounded nucleons on the collision energy was derived. The results are compared to predictions of several models.
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The production of $\Xi (1321)^{-}$ and $\overline{\Xi }(1321)^{+}$ hyperons in inelastic p+p interactions is studied in a fixed target experiment at a beam momentum of 158 $\hbox {Ge}\hbox ...{V}\!/\!c$. Double differential distributions in rapidity ${y}$ and transverse momentum $p_{T}$ are obtained from a sample of 33M inelastic events. They allow to extrapolate the spectra to full phase space and to determine the mean multiplicity of both ${\Xi }{^-} $ and $\overline{\Xi }{^+} $. The rapidity and transverse momentum spectra are compared to transport model predictions. The ${\Xi }{^-} $ mean multiplicity in inelastic p+p interactions at 158 $\hbox {Ge}\hbox {V}\!/\!c$ is used to quantify the strangeness enhancement in A+A collisions at the same centre-of-mass energy per nucleon pair.
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Abstract
This report presents a concept of constructing a detector
dedicated for detection of muons observed during measurements
carried out at the MPD (Multi-Purpose Detector) detector that is
...currently under construction at the NICA facility, Russia, Dubna. It
has been proposed to design and build an additional detector that
will complement the current MPD set and increase its measurement
capabilities. The main goal of this project is to provide
information from cosmic muons that pass the MPD detector in both
in-beam and off-beam experiments. Hence, the detector is called the
MPD COsmic Ray Detector (MCORD).The conceptual design of MCORD is
proposed by a Polish consortium NICA-PL comprising several Polish
scientific institutions.
The data from cosmic ray muons could be used as a trigger for
calibration of other detection systems comprising the MPD
detector. Large surface covered by the MCORD offers also possibility
for efficient registration of muons generated in expanding
atmospheric showers induced by distant sources. Moreover, beyond
some energy threshold, observation of muons originating from decays
of collision products will also be possible. In this report examples
of the MCORD functionality as a part of the MPD detector are
presented.
The MCORD is designed as a universal, fast triggering system built
as a modular reconfigurable construction. The detection system will
be based on plastic scintillators equipped with wavelength shifting
fibers, and silicon photomultipliers (SiPM) will be used for
scintillation readout. The online analysis of received signals will
be performed using digital FPGA modules. Due to the modular design,
the same system (its small part) can be used for both laboratory
testing of other MPD sub-detectors, and the calibration of these
detectors after placing them inside the MPD in off-beam mode. The
full detector will support these systems as an additional trigger,
calibrator, and muon identifier during the normal operation of the
MPD detector with the beam. Thanks to its unique construction, it
will expand the possibilities of collecting scientific data of the
MPD detector with astrophysical observations.
The publication will show the assumptions of the mechanical
structure and electronic systems of the planned detector. The
installation site of the detector as part of the MPD detector will
be described in detail. In the following, the results of simulations
made in preparation for this project will be presented. In
particular, simulations with the CORSIKA code present angular
distributions of particles in cosmic showers in the Dubna city
region. Since muons dominate the cosmic ray showers, the MPD
detector response to expected cosmic muon flux was also
simulated. The results provide information about the muon cut-off
thresholds depending on the MPD detector composition during the
installation campaign. Simulations of muon events that could be used
for MPD subsystems calibration were also performed. The results
shown for various configuration of MCORD detector modules will
enable the estimation of the time necessary to perform such tests in
the future.
Simulations with UrQMD model shows the muon abundances due to
beam-beam collisions. Approximately 90% of muons are created from
pions, whereas the number of muons that reach the MCORD detector is
10 times greater than the number of pions. The MPD detector response
was also simulated under the influence of a stream of various
particles, especially muons. It shows energy dependence of muon
transmission coefficient for MPD with and without ECal
assembled. Assuming requirement for muon transmission above 95%,
the muon cut-off thresholds are 1.6 GeV and 2.0 GeV, respectively.
MCORD detector performance evaluation is also reported. In the case
when we used scintillators with one fiber with a diameter of 1 mm,
the time resolution of about 1.0 ns was recorded, which corresponds
to the positional accuracy (σ
x
) of 7.1 cm. The results of
laboratory tests show that application of a 2 mm diameter WLS fiber
instead of the previously used 1 mm diameter fiber improves the
time resolution to 0.80 ns.
Measurements of inclusive spectra and mean multiplicities of $\pi ^\pm $ , K$^\pm $ , p and ${\bar{\text {p}}}$ produced in inelastic p + p interactions at incident projectile momenta of 20, 31, 40, ...80 and 158 $\text{ GeV }/c$ ( $\sqrt{s} = $ 6.3, 7.7, 8.8, 12.3 and 17.3 $\text{ GeV }$ , respectively) were performed at the CERN Super Proton Synchrotron using the large acceptance NA61/SHINE hadron spectrometer. Spectra are presented as function of rapidity and transverse momentum and are compared to predictions of current models. The measurements serve as the baseline in the NA61/SHINE study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter.
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Measurements of hadron production in p + C interactions at 31 GeV/c are performed using the NA61/SHINE spectrometer at the CERN SPS. The analysis is based on the full set of data collected in 2009 ...using a graphite target with a thickness of 4 % of a nuclear interaction length. Inelastic and production cross sections as well as spectra of $\pi ^{\pm }$ , $K^{\pm }$ , p, $K^0_S$ and $\varLambda $ are measured with high precision. These measurements are essential for improved calculations of the initial neutrino fluxes in the T2K long-baseline neutrino oscillation experiment in Japan. A comparison of the NA61/SHINE measurements with predictions of several hadroproduction models is presented.
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NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a multi-purpose experimental facility to study hadron production in hadron-proton, hadron-nucleus and nucleus-nucleus collisions at the CERN ...Super Proton Synchrotron. It recorded the first physics data with hadron beams in 2009 and with ion beams (secondary super(7)Be beams) in 2011. NA61/SHINE has greatly profited from the long development of the CERN proton and ion sources and the accelerator chain as well as the H2 beamline of the CERN North Area, The latter has recently been modified to also serve as a fragment separator as needed to produce the Be beams for NA61/SHINE. Numerous components of the NA61/SHINE set-up were inherited from its predecessors, in particular, the last one, the NA49 experiment. Important new detectors and upgrades of the legacy equipment were introduced by the NA61/SHINE Collaboration. This paper describes the state of the NA61/SHINE facility - the beams and the detector system - before the CERN Long Shutdown I, which started in March 2013.
This paper reports measurements of two-pion femtoscopic correlations in Be+Be collisions at a beam momentum of 150
A
GeV
/
c
(energy available in the center-of-mass system for nucleon pair
s
NN
=
...16.84
GeV) by the NA61/SHINE experiment at the CERN SPS accelerator. The obtained momentum space correlation functions can be well described by a Lévy distributed source model. The transverse mass dependence of the Lévy source parameters is presented, and their possible theoretical interpretations are discussed. The results show that the Lévy exponent
α
is approximately constant as a function of
m
T
, and far from both the Gaussian case of
α
=
2
or the conjectured value at the critical endpoint,
α
=
0.5
. The radius scale parameter
R
shows a slight decrease in
m
T
, which can be explained as a signature of transverse flow. Finally, an approximately constant trend of the intercept parameter
λ
as a function of
m
T
was observed, similar to previous NA44 S + Pb results (obtained with a Gaussian approximation, but unlike RHIC results).
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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
Δ
P
T
,
N
,
Σ
P
T
,
N
and
Φ
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
U
r
qmd
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.
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This paper presents multiplicity measurements of charged hadrons produced in 120 GeV/$c$ proton-carbon interactions. The measurements were made using data collected at the NA61/SHINE experiment ...during two different data-taking periods, with increased phase space coverage in the second configuration due to the addition of new subdetectors. Particle identification via $dE/dx$ was employed to obtain double-differential production multiplicities of $\pi^+$, $\pi^-$, $p$, $\bar{p}$, $K^+$ and $K^-$. These measurements are presented as a function of laboratory momentum in intervals of laboratory polar angle covering the range from 0 to 450 mrad. They provide crucial inputs for current and future long-baseline neutrino experiments, where they are used to estimate the initial neutrino flux.
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