Measurements Of Particle Production Research Articles

Comparison of strange particle production measurements in central Pb–Pb collisions at $$\sqrt {s_{NN} }$$ = 2.76 and 5.02 TeV by using Monte Carlo simulation models EPOS-1.99 and EPOS-LHC

Comparison of strange particle production measurements in central Pb–Pb collisions at $$\sqrt {s_{NN} }$$ = 2.76 and 5.02 TeV by using Monte Carlo simulation models EPOS-1.99 and EPOS-LHC

Measurements of pi ^- production in ^7Be + ^9Be collisions at beam momenta from 19A to 150A,text{ GeV }!/!c in the NA61/SHINE experiment at the CERN SPS

The NA61/SHINE collaboration studies at the CERN Super Proton Synchrotron (SPS) the onset of deconfinement in hadronic matter by the measurement of particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents results on inclusive double-differential spectra and mean multiplicities of pi ^{-} mesons produced in the 5% most central^7Be + ^9Be collisions at beam momenta of 19A, 30A, 40A, 75A and 150A,text{ GeV }!/!c obtained by the so-called h^- method which does not require any particle identification. The shape of the transverse mass spectra differs from the shapes measured in central Pb + Pb collisions and inelastic p+p interactions. The normalized width of the rapidity distribution decreases with increasing collision energy and is in between the results for inelastic nucleon–nucleon and central Pb + Pb collisions. The mean multiplicity of pions per wounded nucleon in central^7Be + ^9Be collisions is close to that in central Pb + Pb collisions up to 75A,text{ GeV }!/!c. However, at the top SPS energy the result lies between those for nucleon–nucleon and Pb + Pb interactions. The results are discussed in the context of predictions for the onset of deconfinement at the CERN SPS collision energies.

ALICE measures pA collisions: Collectivity in small systems?

Proton-nucleus collisions provide a reference for heavy ion-collisions, to study the signatures deriving from the presence of a complex nuclear structure in the initial state, which confirm that the suppression of high-pThadron production observed in heavy-ion collisions is a genuine effect of the hot deconfined QGP. However, several measurements of particle production in the low and intermediate momentum region indicate the presence of coherent and collective effects, already in small systems, such as the ones produced in p-Pb collisions. Measurements from proton-lead collisions at √sNN = 5.02 TeV obtained by the ALICE experiment at the CERN LHC will be presented and compared to p-p, A-A and d-A experimental results at different collision energies and to the available theoretical model predictions.

Studies of particle production in pp collisions in the forward region at LHCb

The LHCb detector at the LHC has a pseudorapidity coverage (2<η<5) which allows it to perform particle production measurements in a kinematic region where QCD models have large uncertainties. Selected analyses on particle production measurements in pp collisions are summarised in these proceedings. The energy flow has been measured separately for different event classes allowing to probe multi-parton interactions at large η. The measured prompt hadron ratios are important for hadronisation models, while the p‾/p ratio is a good observable to test models of baryon number transport. Charm production has been studied to determine cross-sections and production ratios. All measurements are compared to a variety of theory predictions.

Particle production in p–Pb collisions with ALICE at the LHC

Measurements of the transverse momentum spectra of light flavor particles at intermediate and high pT are an important tool for QCD studies. In pp collisions they provide a baseline for perturbative QCD, while in Pb-Pb they are used to investigate the suppression caused by the surrounding medium. In p-Pb collisions, such measurements provide a reference to disentangle final from initial state effects and thus play an important role in the search for signatures of the formation of a deconfined hot medium. While the comparison of the p-Pb and Pb-Pb data indicates that initial state effects do not play a role in the suppression of hadron production observed at high pT in heavy ion collisions, several measurements of particle production in the low and intermediate pT region indicate the presence of collective effects.

20pAH-6 RHICf実験 : RHICにおける超前方生成粒子測定

20pAH-6 RHICf実験 : RHICにおける超前方生成粒子測定

An empirically derived inorganic sea spray source function incorporating sea surface temperature

Abstract. We have developed an inorganic sea spray source function that is based upon state-of-the-art measurements of sea spray aerosol production using a temperature-controlled plunging jet sea spray aerosol chamber. The size-resolved particle production was measured between 0.01 and 10 μm dry diameter. Particle production decreased non-linearly with increasing seawater temperature (between −1 and 30 °C) similar to previous findings. In addition, we observed that the particle effective radius, as well as the particle surface, particle volume and particle mass, increased with increasing seawater temperature due to increased production of particles with dry diameters greater than 1 μm. By combining these measurements with the volume of air entrained by the plunging jet we have determined the size-resolved particle flux as a function of air entrainment. Through the use of existing parameterisations of air entrainment as a function of wind speed, we were subsequently able to scale our laboratory measurements of particle production to wind speed. By scaling in this way we avoid some of the difficulties associated with defining the "white area" of the laboratory whitecap – a contentious issue when relating laboratory measurements of particle production to oceanic whitecaps using the more frequently applied whitecap method. The here-derived inorganic sea spray source function was implemented in a Lagrangian particle dispersion model (FLEXPART – FLEXible PARTicle dispersion model). An estimated annual global flux of inorganic sea spray aerosol of 5.9 ± 0.2 Pg yr−1 was derived that is close to the median of estimates from the same model using a wide range of existing sea spray source functions. When using the source function derived here, the model also showed good skill in predicting measurements of Na+ concentration at a number of field sites further underlining the validity of our source function. In a final step, the sensitivity of a large-scale model (NorESM – the Norwegian Earth System Model) to our new source function was tested. Compared to the previously implemented parameterisation, a clear decrease of sea spray aerosol number flux and increase in aerosol residence time was observed, especially over the Southern Ocean. At the same time an increase in aerosol optical depth due to an increase in the number of particles with optically relevant sizes was found. That there were noticeable regional differences may have important implications for aerosol optical properties and number concentrations, subsequently also affecting the indirect radiative forcing by non-sea spray anthropogenic aerosols.

Overview of results from ALICE

ALICE is a dedicated experiment for measurements of heavy-ion collisions at the Large Hadron Collider (LHC). A wealth of experimental data recorded in 2010, 2011 and 2012 suggests that a strongly interacting de-confined medium is created in collisions of lead ions at a centre-of-mass energy = 2.76 TeV. In order to quantify the properties of this hot and dense matter, measurements were performed in smaller systems, such as proton-proton and proton-lead, where effects related to the medium are expected to be negligible. We present an overview of recent measurements of particle production and particle correlations in protonproton, Pb-Pb and p-Pb collisions at the LHC by ALICE Collaboration.

ALICE measurements in p–Pb collisions: Charged particle multiplicity, centrality determination and implications for binary scaling

Measurements of particle production in proton-nucleus collisions provide a reference to disentangle final state effects, i.e. signatures of the formation of a deconfined hot medium, from initial state effects, already present in cold nuclear matter. Since many initial state effects are expected to vary as a function of the number of collisions suffered by the incoming proton, it is crucial to estimate the centrality of the collision. In p-Pb collisions categorization of events into different centrality classes using a particle multiplicity distribution is complicated by the low particle multiplicities and the large multiplicity fluctuations. We present ALICE measurements of particle production in p-Pb collisions at sqrt(sNN) = 5.02$ TeV, including the pseudo-rapidity and transverse momentum dependence, we discuss the event classification in centrality classes and its implications for the measurements of nuclear modification factors.

Particle production in the Color Glass Condensate: from electron–proton DIS to proton–nucleus collisions

We study single inclusive hadron production in proton-proton and proton-nucleus collisions in the CGC framework. The parameters in the calculation are obtained by fitting electron-proton deep inelastic scattering data. The obtained dipole-proton amplitude is generalized to dipole-nucleus scattering without any additional nuclear parameters other than the Woods-Saxon distribution. We show that it is possible to use an initial condition without an anomalous dimension and still obtain a good description of the HERA inclusive cross section and LHC single particle production measurements. We argue that one must consistently use the proton transverse area as measured by a high virtuality probe in DIS also for the single inclusive cross section in proton-proton and proton-nucleus collisions, and obtain a nuclear modification factor $R_{pA}$ that at midrapidity approaches unity at large momenta and at all energies.

Conceptual design and performance simulations of super-compact electromagnetic calorimeter

Measurements of particle production at forward rapidities in high energy p-p, p-A and A-A collisions provide access to physics processes at very low Bjorken x. These measurements will allow to study the gluon saturation scale and improve our knowledge of parton distribution in nuclei. Specific requirements must be fulfilled for a calorimeter to successfully operate in high-multiplicity forward region within often stringent space limits. Here we present a study of a conceptual design of super-compact electromagnetic calorimeter being developed at Czech Technical University in Prague. The design of the sampling calorimeter is based on a sandwich structure of thin tungsten and scintillator layers oriented in parallel to the beam. Used optical readout of individual scintillator pads guaranties the required high radiation hardness of the detector. We present simulation of the expected performance of the optical pad readout together with overall detector performance. It is aimed for the detector to allow measuring of high energy photons (1<E<300 GeV) in forward rapidities (2.5 < η < 4).

Measurements of Particle Production in pp Collisions in the Forward Region at the LHC

The phase space coverage of the LHCb detector allows a unique insight into the particle production in the forward region at the LHC. Due to its unique pseudorapidity range and to the possibility of extending the measurements to low transverse momenta, the LHCb data provide important input to the understanding of particle production in a kinematical range where QCD models have large uncertainties. Measurements of the production of charged particles and of the strange phi mesons are presented. In addition the ratio of (Lambda) over bar/Lambda is studied as a function of rapidity and transverse momentum for centre-of-mass energies root s = 0.9 TeV and root s = 7.0 TeV, probing baryon number transport from the beam. Baryon strangeness suppression is evaluated through the measurement of (Lambda) over bar /K-S(0). The LHCb results are compared with lower energy measurements, phenomenological models and Monte Carlo event generators.

NA61/SHINE Physics Program – First Results and Future Plans

The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study properties of the onset of deconfinement. These goals are to be achieved by performing a twodimensional phase diagram (T - {\mu}B) scan measurements of hadron production as a function of collision energy and system size. With its large acceptance and good particle identification NA61/SHINE also performs detailed and precise particle production measurements for the T2K, Pierre Auger Observatory and KASCADEGrande experiments. This contribution summarizes current status and future plans as well as presents the first physics results of the NA61/SHINE experiment.

Diffractive Physics at the CERN Large Hadron Collider

Abstract After a short introduction on diffraction, I briefly review the framework used to describe non-perturbative QCD phenomena in hadron-hadron interactions. Then I explain why diffractive processes cannot be ignored at LHC and how ALICE, ATLAS, CMS, LHCb and TOTEM study diffraction, with emphasis on how inclusive particle production measurements are normalised to non-single diffractive and inelastic event classes.

Erratum: Measurement of particle production and inclusive differential cross sections inpp¯collisions ats=1.96 TeV[Phys. Rev. D79, 112005 (2009)

Received 18 November 2010DOI:https://doi.org/10.1103/PhysRevD.82.119903© 2010 The American Physical Society

Measurement of particle production and inclusive differential cross sections inpp¯collisions ats=1.96 TeV

We report a set of measurements of particle production in inelastic pbar{p} collisions collected with a minimum-bias trigger at the Tevatron Collider with the CDF II experiment. The inclusive charged particle transverse momentum differential cross section is measured, with improved precision, over a range about ten times wider than in previous measurements. The former modeling of the spectrum appears to be incompatible with the high particle momenta observed. The dependence of the charged particle transverse momentum on the event particle multiplicity is analyzed to study the various components of hadron interactions. This is one of the observable variables most poorly reproduced by the available Monte Carlo generators. A first measurement of the event transverse energy sum differential cross section is also reported. A comparison with a Pythia prediction at the hadron level is performed. The inclusive charged particle differential production cross section is fairly well reproduced only in the transverse momentum range available from previous measurements. At higher momentum the agreement is poor. The transverse energy sum is poorly reproduced over the whole spectrum. The dependence of the charged particle transverse momentum on the particle multiplicity needs the introduction of more sophisticated particle production mechanisms, such as multiple parton interactions, in order to be better explained.

The Main Injector Particle Production Experiment

It is currently impossible to apply the theory of strong interactions, QCD, to compute non-perturbative hadron interaction cross sections from first principles. Thus high quality hadronic particle production measurements are needed to fully understand the data from experiments that have hadronic interactions as a signal or background. This includes atmospheric and accelerator neutrino experiments, calorimetry and hadronic shower simulation. Such data can also be used to test observed regularities in particle production such as scaling relations in inclusive reactions with some precision. The spectrum of baryon resonances predicted by QCD includes many states that have not been observed. Measurements of pion, kaon, and proton beams on a liquid hydrogen target at beam momenta around 1 GeV/c will provide important input to searches for missing baryon resonances. We review status, results, and prospects of particle production measurements at Fermilab.

Review of the safety of LHC collisions

The safety of collisions at the Large Hadron Collider (LHC) was studied in 2003 by the LHC Safety Study Group, who concluded that they presented no danger. Here we review their 2003 analysis in light of additional experimental results and theoretical understanding, which enable us to confirm, update and extend the conclusions of the LHC Safety Study Group. The LHC reproduces in the laboratory, under controlled conditions, collisions at centre-of-mass energies, less than those reached in the atmosphere by some of the cosmic rays that have been bombarding the Earth for billions of years. We recall the rates for the collisions of cosmic rays with the Earth, Sun, neutron stars, white dwarfs and other astronomical bodies at energies higher than the LHC. The stability of astronomical bodies indicates that such collisions cannot be dangerous. Specifically, we study the possible production at the LHC of hypothetical objects such as vacuum bubbles, magnetic monopoles, microscopic black holes and strangelets, and find no associated risks. Any microscopic black holes produced at the LHC are expected to decay by Hawking radiation before they reach the detector walls. If some microscopic black holes were stable, those produced by cosmic rays would be stopped inside the Earth or other astronomical bodies. The stability of astronomical bodies strongly constrains the possible rate of accretion by any such microscopic black holes, so that they present no conceivable danger. In the case of strangelets, the good agreement of measurements of particle production at RHIC with simple thermodynamic models severely constrains the production of strangelets in heavy-ion collisions at the LHC, which also present no danger.

Review of Recent and Future Needs in Hadronic Flavor Particle Production Measurements

Interactions of energetic particles on target nuclei producing secondary particles will be reviewed. Current simulation codes rely upon poorly measured results from the past. While current neutrino experiments, both atmospheric and accelerator based, rely upon Kaon and pion production measurements which are poorly known and dominate their errors. The goal for the current round of experiments are to dramatically improve these measurements while improvments beyond this are still needed. It is not only of interest to neutrino experiments, but also for designing calorimeters for the the International Linear Collider which must achieve unprecedented resolutions for reaching their stated physics goals.

Recent high pT measurements in STAR

After five years of data taking, the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory provides precise measurements of particle production at high transverse momentum in p-p, d-Au, and Au-Au collisions at √SNN = 200 GeV. We review recent results on the flavor dependence of high pT particle suppression and hadron particle spectra at √SNN = 62.4 GeV. New results on two-particle angular correlations for identified trigger particles and for low momentum associated charged hadrons in p-p and Au-Au as well as near-side .Δη correlations will be presented and discussed.