Exhibiting the ALICE experiment

Among the many outreach and communication tools available in our digital era, traditional tools such as exhibitions still hold an important place. The ALICE collaboration is setting up a new exhibition at the experiment's site, as part of the ALICE Visitor Centre. Its goal is to communicate to visitors the physics and the tools and methods used by ALICE. It combines modern technology such as video mapping with real detector items, aiming to fascinate the visitors and give them an immersive experience of a high energy physics experiment. The development process, the messages to be delivered and the choices for the contents and the way of exhibiting them are discussed; and the final design and present status of the project are presented.Comment: 6 pages, 9 figures, Fifth Annual Large Hadron Collider Physics Conferenc

The time of flight detector for the ALICE experiment

Abstract For the identification of particles in the momentum range 0.5 to 2.5 GeV /c the ALICE experiment uses a time of flight array. The detectors used are Multigap Resistive Plate Chambers (MRPC) with 50 ps time resolution. The whole array covers a ∼150 m 2 area and consists of detector elements in the form of MRPC strips. To cope with the high multiplicity expected for heavy ion collisions, the TOF array is segmented; pickup pads of 2.5×3.5 cm 2 are used. Thus the whole system will have 160 000 read-out channels. Here we present results of the R&D program of the last 3 years, which led to the design of the final TOF system for ALICE

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

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV

Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

Peer reviewe

Elliptic flow of muons from heavy-flavour hadron decays at forward rapidity in Pb-Pb collisions at root s(NN)=2.76TeV

The elliptic flow, v(2), of muons from heavy-flavour hadron decays at forward rapidity (2.5 <y <4) is measured in Pb-Pb collisions at root s(NN)= 2.76TeVwith the ALICE detector at the LHC. The scalar product, two- and four-particle Q cumulants and Lee-Yang zeros methods are used. The dependence of the v(2) of muons from heavy-flavour hadron decays on the collision centrality, in the range 0-40%, and on transverse momentum, p(T), is studied in the interval 3 <p(T)<10 GeV/c. A positive v(2) is observed with the scalar product and two-particle Q cumulants in semi-central collisions (10-20% and 20-40% centrality classes) for the p(T) interval from 3 to about 5GeV/c with a significance larger than 3 sigma, based on the combination of statistical and systematic uncertainties. The v(2) magnitude tends to decrease towards more central collisions and with increasing pT. It becomes compatible with zero in the interval 6 <p(T)<10 GeV/c. The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V.Peer reviewe

Pseudorapidity and transverse-momentum distributions of charged particles in proton-proton collisions at root s=13 TeV

The pseudorapidity (eta) and transverse-momentum (p(T)) distributions of charged particles produced in proton-proton collisions are measured at the centre-of-mass energy root s = 13 TeV. The pseudorapidity distribution in vertical bar eta vertical bar <1.8 is reported for inelastic events and for events with at least one charged particle in vertical bar eta vertical bar <1. The pseudorapidity density of charged particles produced in the pseudorapidity region vertical bar eta vertical bar <0.5 is 5.31 +/- 0.18 and 6.46 +/- 0.19 for the two event classes, respectively. The transverse-momentum distribution of charged particles is measured in the range 0.15 <p(T) <20 GeV/c and vertical bar eta vertical bar <0.8 for events with at least one charged particle in vertical bar eta vertical bar <1. The evolution of the transverse momentum spectra of charged particles is also investigated as a function of event multiplicity. The results are compared with calculations from PYTHIA and EPOS Monte Carlo generators. (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

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

Outreach and educational activities of the ALICE collaboration during the COVID pandemic

With the onset of the COVID pandemic in 2020 all outreach and educational activities with in-person participation had to stop. The ALICE Collaboration adapted to the new situation and continued reaching out to the public using the multitude of online tools and platforms available. Here we focus on two of our main outreach activities, virtual visits and masterclasses. With the cancellation of all in-person visits, virtual visits became the only way to explore the experiment. ALICE had already been offering virtual visits for remote audiences with equipment installed in the ALICE Run Control Centre (ARC). We recently acquired dedicated mobile equipment for the virtual visits to the cavern and developed a scenario which includes both the cavern and the ARC as well as a Q&A; session. In this way, visitors from many countries have the opportunity to interact with scientists and to see parts of the experiment that they would never be able to see during a real visit. Concerning the International Masterclasses (IMC) programme, ALICE has been participating ever since measurements based on LHC data were introduced in it. The packages used had been developed by simplifying the ALICE event display and were based on ROOT. With the spreading of the COVID pandemic the 2020 IMC programme was interrupted. In 2021, with most activities taking place remotely, it was obvious that web-based versions were needed. The implementation of such versions allowed us to hold remote masterclasses for high-school students, thus ensuring the continuity of this important outreach activity of our community. In addition we reached new countries and also involved high-school teachers in this global effort