Status of the ALICE experiment at the LHC

The status of the ALICE experiment is presented. ALICE is the LHC experiment devoted to heavy ion collisions. Preparing for the first lead-lead run, foreseen in November 2010, ALICE is successfully collecting data in proton-proton collisions at the LHC since November 2009, exploiting the charateristics of the detector for its proton-proton physics program. First results are briefly reviewed with an emphasis on performance of its detector sub-systems.Comment: Proceedings of the HCP 2010 Conference - Toronto, 23-27 August 201

Soft QCD, minimum bias and diffraction: results from ALICE

We report recent results from the ALICE experiment at the LHC for minimum bias pp collisions. This overview includes results on inelastic cross section, with analysis of single and double diffractive events; the study of hadron production mechanisms, both for inclusive and identified particles; Bose-Einstein correlations; and fluctuations in $$Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 4 pages, 11 figure

The cosmic ray primary composition in the "knee" region through the EAS electromagnetic and muon measurements at EAS-TOP

Abstract The evolution of the cosmic ray primary composition in the energy range 10 6 –10 7 GeV (i.e. the "knee" region) is studied by means of the e.m. and muon data of the Extensive Air Shower EAS-TOP array (Campo Imperatore, National Gran Sasso Laboratories). The measurement is performed through: (a) the correlated muon number ( N μ ) and shower size ( N e ) spectra, and (b) the evolution of the average muon numbers and their distributions as a function of the shower size. From analysis (a) the dominance of helium primaries at the knee, and therefore the possibility that the knee itself is due to a break in their energy spectrum (at E k He =(3.5±0.3)×10 6 GeV) are deduced. Concerning analysis (b), the measurement accuracies allow the classification in terms of three mass groups: light (p,He), intermediate (CNO), and heavy (Fe). At primary energies E 0 ≈10 6 GeV the results are consistent with the extrapolations of the data from direct experiments. In the knee region the obtained evolution of the energy spectra leads to: (i) an average steep spectrum of the light mass group ( γ p,He >3.1), (ii) a spectrum of the intermediate mass group harder than the one of the light component ( γ CNO ≃2.75, possibly bending at E k CNO ≈(6–7)×10 6 GeV), (iii) a constant slope for the spectrum of the heavy primaries ( γ Fe ≃2.3–2.7) consistent with the direct measurements. In the investigated energy range, the average primary mass increases from 〈ln A 〉=1.6–1.9 at E 0 ≃1.5×10 6 GeV to 〈ln A 〉=2.8–3.1 at E 0 ≃1.5×10 7 GeV. The result supports the standard acceleration and propagation models of galactic cosmic rays that predict rigidity dependent cut-offs for the primary spectra of the different nuclei. The uncertainties connected to the hadronic interaction model (QGSJET in CORSIKA) used for the interpretation are discussed

SNEWS: The SuperNova Early Warning System

This paper provides a technical description of the SuperNova Early Warning System (SNEWS), an international network of experiments with the goal of providing an early warning of a galactic supernova.Comment: 25 pages, for New Journal of Physics Focus Issue on Neutrino Physic

QCD challenges from pp to AA collisions: 4th edition

This paper is a write-up of the ideas that were presented, developed and discussed at the fourth International Workshop on QCD Challenges from pp to AA, which took place in February 2023 in Padua, Italy. The goal of the workshop was to focus on some of the open questions in the field of high-energy heavy-ion physics and to stimulate the formulation of concrete suggestions for making progresses on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results

QCD challenges from pp to AA collisions: 4th edition

This paper is a write-up of the ideas that were presented, developed and discussed at the fourth International Workshop on QCD Challenges from pp to AA, which took place in February 2023 in Padua, Italy. The goal of the workshop was to focus on some of the open questions in the field of high-energy heavy-ion physics and to stimulate the formulation of concrete suggestions for making progresses on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results

QCD challenges from pp to AA collisions -- 4th edition

This paper is a write-up of the ideas that were presented, developed and discussed at the fourth International Workshop on QCD Challenges from pp to AA, which took place in February 2023 in Padua, Italy. The goal of the workshop was to focus on some of the open questions in the field of high-energy heavy-ion physics and to stimulate the formulation of concrete suggestions for making progresses on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results

Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe