ALICE results from the first Pb-Pb run at the CERN LHC

After 20 years of preparation, the dedicated heavy ion experiment ALICE took first data at the CERN LHC accelerator with proton collisions at the end of 2009 and with lead beams at the end of 2010. This article will give a brief overview of the main results presented at the Quark Matter 2011 conference.Comment: Inited talk at the 22nd International Conference on Ultra-relativistic Nucleus-Nucleus Collision (Quark Matter 2011), 23 - 28 May 2011, Annecy, Franc

First Results from Pb+Pb collisions at the LHC

At the end of 2010, the CERN Large Hadron Collider started operation with heavy ion beams, colliding lead nuclei at a centre-of-mass energy of 2.76 TeV/nucleon and opening a new era in ultra-relativistic heavy ion physics at energies exceeding previous accelerators by more than an order of magnitude. This review summarizes the results from the first year of heavy ion physics at LHC obtained by the three experiments participating in the heavy ion program, ALICE, ATLAS, and CMS.Comment: To appear in Annual Review of Nuclear and Particle Scienc

Approaches on self-healing of an interpenetrating metal ceramic composite

An interpenetrating metal ceramic composite (IMCC), manufactured via gas pressure infiltration of AlSi10Mg melt into a open porous Al2O3-preform, was investigated upon the ability of self-healing. A specific damage is introduced into the IMCC first. Then microstructural investigations are carried out at the damaged samples and for self-healing treated samples. The nature of the interpenetrating structure is used to heat the composite above the solidus temperature of the metallic phase and provide a shape stability by the ceramic phase to melt the metal and fill the cracks formed before. The investigation is systematically compared to the results of the undamaged samples as well as the pre-damaged samples without treatment for self-healing. The microstructural results show a change in crack geometry and therefore the possibility of self-healing. Nevertheless, open questions in process control as well as parameter- optimization require further research to achieve microstructural improvement of the healed samples above the performance of the pre-damaged ones

NA49/NA61: results and plans on beam energy and system size scan at the CERN SPS

This paper presents results and plans of the NA49 and NA61/SHINE experiments at the CERN Super Proton Synchrotron concerning the study of relativistic nucleus-nucleus interactions. First, the NA49 evidence for the energy threshold of creating quark-gluon plasma, the onset of deconfinement, in central lead-lead collisions around 30A GeV is reviewed. Then the status of the NA61/SHINE systematic study of properties of the onset of deconfinement is presented. Second, the search for the critical point of strongly interacting matter undertaken by both experiments is discussed. NA49 measured large fluctuations at the top SPS energy, 158A GeV, in collisions of light and medium size nuclei. They seem to indicate that the critical point exists and is located close to baryonic chemical potential of about 250 MeV. The NA61/SHINE beam energy and system size scan started in 2009 will provide evidence for the existence of the critical point or refute the interpretation of the NA49 fluctuation data in terms of the critical point.Comment: 11 pages, invited talk at Quark Matter 201

D meson nuclear modification factors in Pb-Pb collisions at {\surd}sNN = 2.76 TeV, measured with the ALICE detector

The ALICE experiment has measured the D meson production in pp and Pb-Pb collisions at the LHC at {\surd}s = 7 and 2.76 TeV and {\surd}sNN = 2.76 TeV respectively, via the exclusive reconstruction of hadronic decay channels. The analyses of the D0{\to}K-pi+ and D+{\to}K-pi+pi+ channels will be described and the preliminary results for the D0 and D+ nuclear modification factor will be presented.Comment: Proceedings of Quark Matter 2011 conference. 4 pages, 4 figures. The slides of the talk can be found at the link: http://indico.cern.ch/materialDisplay.py?contribId=591&sessionId=53&materialId=slides&confId=3024

Medium information from anisotropic flow and jet quenching in relativistic heavy ion collisions

Within a multiphase transport (AMPT) model, where the initial conditions are obtained from the recently updated HIJING 2.0 model, the recent anisotropic flow and suppression data for charged hadrons in Pb+Pb collisions at the LHC center of mass energy of 2.76 TeV are explored to constrain the properties of the partonic medium formed. In contrast to RHIC, the measured centrality dependence of charged hadron multiplicity dN_ch/deta at LHC provides severe constraint to the largely uncertain gluon shadowing parameter s_g. We find final-state parton scatterings reduce considerably hadron yield at midrapidity and enforces a smaller s_g to be consistent with dN_ch/deta data at LHC. With the parton shadowing so constrained, hadron production and flow over a wide transverse momenta range are investigated in AMPT. The model calculations for the elliptic and triangular flow are found to be in excellent agreement with the RHIC data, and predictions for the flow coefficients v_n(p_T, cent) at LHC are given. The magnitude and pattern of suppression of the hadrons in AMPT are found consistent with the measurements at RHIC. However, the suppression is distinctly overpredicted in Pb+Pb collisions at the LHC energy. Reduction of the QCD coupling constant alpha_s by ~30% in the higher temperature plasma formed at LHC reproduces the measured hadron suppression.Comment: Talk given by Subrata Pal at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

Investigation on the recycling potential of additively manufactured carbon fiber reinforced PA 6.6

Carbon fiber reinforced polymers (CFRP) are already used in a wide range of applications such as automotive, aerospace and renewable energy industries and demand on this material class is increasing steadily. As demand increases, the amount of CFRP waste, either from production or at the end of life of components, increases simultaneously and sustainable solutions such as disposal, reuse or recycling of fiber reinforced materials getting more and more important. In this paper one possibility for recycling short carbon fiber reinforced polyamide 6.6 (CF/PA 6.6) is presented. The recycling process includes shredding of the material, drying and filament extrusion to enable a reuse of the material with an additive manufacturing process. The focus of this investigation is on the mechanical properties of the recycled filaments itself as well as on the 3D printed specimen considered recycled filaments. The properties at different stages of the short carbon fiber reinforced polyamide 6.6 recycling process were investigated, including the juvenile CF/PA 6.6 as well as specimens made from one- or two-times recycled material. Mechanical performance was evaluated by tensile, bending and impact testing. Experimental results pointed out that no significant difference in performance of juvenile and recycled materials was observed for tensile and flexural loads. The impact strength of the recycled specimen decreased to a small extent

Transverse momentum distributions and their forward- backward correlations in the percolating colour string approach

The forward-backward correlations in the $p_T$ distributions, which present a clear signature of non-linear effects in particle production, are studied in the model of percolating colour strings. Quantitative predictions are given for these correlations at SPS, RHIC and LHC energies. Interaction of strings also naturally explains the flattening of $p_T$ distributions and increase of $$ with energy and atomic number for nuclear collisionsComment: 6 pages in LaTex, 3 figures in Postscrip