We report on the inclusive Formula omitted production cross section measured at the CERN Large Hadron Collider in proton-proton collisions at a center-of-mass energy Formula omitted TeV. The Formula ...omitted mesons are reconstructed in the Formula omitted decay channel and the measurements are performed at midrapidity ( Formula omitted) in the transverse-momentum interval Formula omitted GeV/ Formula omitted, using a minimum-bias data sample corresponding to an integrated luminosity Formula omitted and an Electromagnetic Calorimeter triggered data sample with Formula omitted. The Formula omitted-integrated Formula omitted production cross section at midrapidity, computed using the minimum-bias data sample, is Formula omitted. An approximate logarithmic dependence with the collision energy is suggested by these results and available world data, in agreement with model predictions. The integrated and Formula omitted-differential measurements are compared with measurements in pp collisions at lower energies and with several recent phenomenological calculations based on the non-relativistic QCD and Color Evaporation models.
Measurements of event-by-event fluctuations of charged-particle multiplicities in Pb-Pb collisions at Formula omitted Formula omitted 2.76 TeV using the ALICE detector at the CERN Large Hadron ...Collider (LHC) are presented in the pseudorapidity range Formula omitted and transverse momentum Formula omitted GeV/c. The amplitude of the fluctuations is expressed in terms of the variance normalized by the mean of the multiplicity distribution. The Formula omitted and Formula omitted dependences of the fluctuations and their evolution with respect to collision centrality are investigated. The multiplicity fluctuations tend to decrease from peripheral to central collisions. The results are compared to those obtained from HIJING and AMPT Monte Carlo event generators as well as to experimental data at lower collision energies. Additionally, the measured multiplicity fluctuations are discussed in the context of the isothermal compressibility of the high-density strongly-interacting system formed in central Pb-Pb collisions.
Two-particle Azimuthal correlations are measured with the ALICE apparatus in pp collisions at Formula omitted 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 ( Formula omitted) or baryon ( Formula omitted) with transverse momentum Formula omitted GeV/ Formula omitted is produced. Azimuthal correlations between kaons or Formula omitted hyperons with other hadrons are presented at midrapidity for a broad range of the trigger ( Formula omitted GeV/ Formula omitted) and associated particle Formula omitted (1 GeV/ Formula omitted Formula omitted), for minimum-bias events and as a function of the event multiplicity. The near- and away-side peak yields are compared for the case of either Formula omitted or Formula omitted( Formula omitted) being the trigger particle with that of inclusive hadrons (a sample dominated by pions). In addition, the measurements are compared with predictions from PYTHIA 8 and EPOS LHC event generators.
The coherent photoproduction of Formula omitted and Formula omitted mesons was measured in ultra-peripheral Pb-Pb collisions at a center-of-mass energy Formula omitted TeV with the ALICE detector. ...Charmonia are detected in the central rapidity region for events where the hadronic interactions are strongly suppressed. The Formula omitted is reconstructed using the dilepton ( Formula omitted) and proton-antiproton decay channels, while for the Formula omitted the dilepton and the Formula omitted decay channels are studied. The analysis is based on an event sample corresponding to an integrated luminosity of about 233 Formula omitted. The results are compared with theoretical models for coherent Formula omitted and Formula omitted photoproduction. The coherent cross section is found to be in a good agreement with models incorporating moderate nuclear gluon shadowing of about 0.64 at a Bjorken-x of around Formula omitted, such as the EPS09 parametrization, however none of the models is able to fully describe the rapidity dependence of the coherent Formula omitted cross section including ALICE measurements at forward rapidity. The ratio of Formula omitted to Formula omitted coherent photoproduction cross sections was also measured and found to be consistent with the one for photoproduction off protons.
The TDCpix is a novel pixel readout ASIC for the NA62 Gigatracker detector. NA62 is a new experiment being installed at the CERN Super Proton Synchrotron. Its Gigatracker detector shall provide ...on-beam tracking and time stamping of individual particles with a time resolution of 150psrms. It will consist of three tracking stations, each with one hybrid pixel sensor. The peak flow of particles crossing the detector modules reaches 1.27MHz/mm2 for a total rate of about 0.75GHz. Ten TDCpix chips will be bump-bonded to every silicon pixel sensor. Each chip shall perform time stamping of 100M particle hits per second with a detection efficiency above 99% and a timing accuracy better than 200ps rms for an overall three-station-setup time resolution of better than 150ps. The TDCpix chip has been designed in a 130nm CMOS technology. It will feature 45×40 square pixels of 300×300μm2 and a complex End of Column peripheral region including an array of TDCs based on DLLs, four high speed serializers, a low-jitter PLL, readout and control circuits. This contribution will describe the complete design of the final TDCpix ASIC. It will discuss design choices, the challenges faced and some of the lessons learned. Furthermore, experimental results from the testing of circuit prototypes will be presented. These demonstrate the achievement of key performance figures such as a time resolution of the processing chain of 75ps rms with a laser sent to the center of the pixel and the capability of time stamping charged particles with an overall resolution below 200psrms.
•Feasibility demonstration of a silicon pixel detector with sub-ns time tagging capability.•Demonstrator detector assembly with a time resolution of 75ps RMS with laser charge injection; 170ps RMS with particle beam.•Design of trigger-less TDCpix ASIC with 1800pixels, 720 TDC channels and 4 3.2Gbit/s serializers.
Production of pions, kaons Acharya, S; Adamová, D; Adler, A ...
The European physical journal. C, Particles and fields,
07/2021, Letnik:
81, Številka:
7
Journal Article
The first measurement of the production of pions, kaons, (anti-)protons and Formula omitted mesons at midrapidity in Xe-Xe collisions at Formula omitted is presented. Transverse momentum ( Formula ...omitted) spectra and Formula omitted-integrated yields are extracted in several centrality intervals bridging from p-Pb to mid-central Pb-Pb collisions in terms of final-state multiplicity. The study of Xe-Xe and Pb-Pb collisions allows systems at similar charged-particle multiplicities but with different initial geometrical eccentricities to be investigated. A detailed comparison of the spectral shapes in the two systems reveals an opposite behaviour for radial and elliptic flow. In particular, this study shows that the radial flow does not depend on the colliding system when compared at similar charged-particle multiplicity. In terms of hadron chemistry, the previously observed smooth evolution of particle ratios with multiplicity from small to large collision systems is also found to hold in Xe-Xe. In addition, our results confirm that two remarkable features of particle production at LHC energies are also valid in the collision of medium-sized nuclei: the lower proton-to-pion ratio with respect to the thermal model expectations and the increase of the Formula omitted-to-pion ratio with increasing final-state multiplicity.
The production of Formula omitted, Formula omitted, Formula omitted, Formula omitted, Formula omitted, Formula omitted, Formula omitted, Formula omitted, Formula omitted, and their antiparticles was ...measured in inelastic proton-proton (pp) collisions at a center-of-mass energy of Formula omitted = 13 TeV at midrapidity ( Formula omitted) as a function of transverse momentum ( Formula omitted) using the ALICE detector at the CERN LHC. Furthermore, the single-particle Formula omitted distributions of Formula omitted, Formula omitted, and Formula omitted in inelastic pp collisions at Formula omitted TeV are reported here for the first time. The Formula omitted distributions are studied at midrapidity within the transverse momentum range Formula omitted GeV/c, depending on the particle species. The Formula omitted spectra, integrated yields, and particle yield ratios are discussed as a function of collision energy and compared with measurements at lower Formula omitted and with results from various general-purpose QCD-inspired Monte Carlo models. A hardening of the spectra at high Formula omitted with increasing collision energy is observed, which is similar for all particle species under study. The transverse mass and Formula omitted scaling properties of hadron production are also studied. As the collision energy increases from Formula omitted = 7-13 TeV, the yields of non- and single-strange hadrons normalized to the pion yields remain approximately constant as a function of Formula omitted, while ratios for multi-strange hadrons indicate enhancements. The Formula omitted-differential cross sections of Formula omitted, Formula omitted and Formula omitted ( Formula omitted) are compared with next-to-leading order perturbative QCD calculations, which are found to overestimate the cross sections for Formula omitted and Formula omitted ( Formula omitted) at high Formula omitted.
![Inclusive [Formula omitted]...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1434-6044/small "Inclusive [Formula omitted] production at midrapidity in pp collisions at [Formula omitted] TeV")
PDF
