Click chemistry of multi-walled carbon nanotubes-G-1,3-diazido-2-isopropanol with alkyne groups

The click chemistry was employed on oxidized multiwall carbon nanotubes for their functionalization with 1,3-diazido-2-isopropanol (2N3OH). Phenylacetylene and propargylamine are used as alkyne groups, catalyzed with copper iodide (I). The chemical and structural characterization are described starting from the Raman and infrared spectroscopy as well as the realization of an elemental combustion analysis, transmission electron microscopy and nuclear magnetic resonance (NMR)CONACY

Multiplicity dependence of light (anti-)nuclei production in p–Pb collisions at sNN=5.02 TeV

The measurement of the deuteron and anti-deuteron production in the rapidity range −1 < y < 0 as a function of transverse momentum and event multiplicity in p–Pb collisions at √sNN = 5.02 TeV is presented. (Anti-)deuterons are identified via their specific energy loss dE/dx and via their time-of- flight. Their production in p–Pb collisions is compared to pp and Pb–Pb collisions and is discussed within the context of thermal and coalescence models. The ratio of integrated yields of deuterons to protons (d/p) shows a significant increase as a function of the charged-particle multiplicity of the event starting from values similar to those observed in pp collisions at low multiplicities and approaching those observed in Pb–Pb collisions at high multiplicities. The mean transverse particle momenta are extracted from the deuteron spectra and the values are similar to those obtained for p and particles. Thus, deuteron spectra do not follow mass ordering. This behaviour is in contrast to the trend observed for non-composite particles in p–Pb collisions. In addition, the production of the rare 3He and 3He nuclei has been studied. The spectrum corresponding to all non-single diffractive p-Pb collisions is obtained in the rapidity window −1 < y < 0 and the pT-integrated yield dN/dy is extracted. It is found that the yields of protons, deuterons, and 3He, normalised by the spin degeneracy factor, follow an exponential decrease with mass number

Higher harmonic non-linear flow modes of charged hadrons in Pb-Pb collisions at sNN\sqrt{s_{\rm{NN}}} = 5.02 TeV

International audienceAnisotropic flow coefficients, v$_{n}$, non-linear flow mode coefficients, χ$_{n,mk}$, and correlations among different symmetry planes, ρ$_{n,mk}$ are measured in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. Results obtained with multi-particle correlations are reported for the transverse momentum interval 0.2 < p$_{T}$< 5.0 GeV/c within the pseudorapidity interval 0.4 < |η| < 0.8 as a function of collision centrality. The v$_{n}$ coefficients and χ$_{n,mk}$ and ρ$_{n,mk}$ are presented up to the ninth and seventh harmonic order, respectively. Calculations suggest that the correlations measured in different symmetry planes and the non-linear flow mode coefficients are dependent on the shear and bulk viscosity to entropy ratios of the medium created in heavy-ion collisions. The comparison between these measurements and those at lower energies and calculations from hydrodynamic models places strong constraints on the initial conditions and transport properties of the system.[graphic not available: see fulltext

Production of pions, kaons, (anti-)protons and ϕ\phi mesons in Xe–Xe collisions at sNN\sqrt{s_{\mathrm{NN}}} = 5.44 TeV

The first measurement of the production of pions, kaons, (anti-)protons and $\phi$ mesons at midrapidity in Xe–Xe collisions at $\sqrt{s_{\mathrm{NN}}} = 5.44~\text {TeV}$ is presented. Transverse momentum ($p_{\mathrm{T}}$) spectra and $p_{\mathrm{T}}$-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 $\phi$-to-pion ratio with increasing final-state multiplicity

J/ψ\psi production as a function of charged-particle multiplicity in p-Pb collisions at sNN = 8.16\sqrt{\textit{s}_{\rm NN}}~=~8.16 TeV

Inclusive J/ψ yields and average transverse momenta in p-Pb collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV are measured as a function of the charged-particle pseudorapidity density with ALICE. The J/ψ mesons are reconstructed at forward (2.03 < y$_{cms}$< 3.53) and backward (−4.46 < y$_{cms}$< −2.96) center-of-mass rapidity in their dimuon decay channel while the charged-particle pseudorapidity density is measured around midrapidity. The J/ψ yields at forward and backward rapidity normalized to their respective average values increase with the normalized charged-particle pseudorapidity density, the former showing a weaker increase than the latter. The normalized average transverse momenta at forward and backward rapidity manifest a steady increase from low to high charged-particle pseudorapidity density with a saturation beyond the average value

Jet-associated deuteron production in pp collisions at s=13 TeV

International audienceDeuteron production in high-energy collisions is sensitive to the space–time evolution of the collision system, and is typically described by a coalescence mechanism. For the first time, we present results on jet-associated deuteron production in pp collisions at s=13 TeV, providing an opportunity to test the established picture for deuteron production in events with a hard scattering. Using a trigger particle with high transverse-momentum (pT&gt;5 GeV/c) as a proxy for the presence of a jet at midrapidity, we observe a measurable population of deuterons being produced around the jet proxy. The associated deuteron yield measured in a narrow angular range around the trigger particle differs by 2.4–4.8 standard deviations from the uncorrelated background. The data are described by PYTHIA model calculations featuring baryon coalescence

Elliptic Flow of Electrons from Beauty-Hadron Decays in Pb-Pb Collisions at sNN\sqrt {s_{NN}} = 5.02 TeV

The elliptic flow of electrons from beauty hadron decays at midrapidity (|y|<0.8) is measured in Pb-Pb collisions at $\sqrt {s_{NN}}$ = 5.02 TeV with the ALICE detector at the LHC. The azimuthal distribution of the particles produced in the collisions can be parametrized with a Fourier expansion, in which the second harmonic coefficient represents the elliptic flow, $v_2$. The $v_2$ coefficient of electrons from beauty hadron decays is measured for the first time in the transverse momentum ($p_T$) range 1.3–6 GeV/c in the centrality class 30%–50%. The measurement of electrons from beauty-hadron decays exploits their larger mean proper decay length cτ ≈ 500 μm compared to that of charm hadrons and most of the other background sources. The $v_2$ of electrons from beauty hadron decays at midrapidity is found to be positive with a significance of 3.75 σ. The results provide insights into the degree of thermalization of beauty quarks in the medium. A model assuming full thermalization of beauty quarks is strongly disfavored by the measurement at high $p_T$, but is in agreement with the results at low $p_T$. Transport models including substantial interactions of beauty quarks with an expanding strongly interacting medium describe the measurement within uncertainties

Coherent J/ψ\psi photoproduction at forward rapidity in ultra-peripheral Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm{NN}}}=5.02 TeV

The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photoproduction in ultra-peripheral Pb–Pb collisions at a center-of-mass energy $\sqrt{s_{\rm NN}}$ = 5.02 TeV. The J/ψ is detected via its dimuon decay in the forward rapidity region (−4.0 < y <−2.5 ) for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 750 $\mu$b$^{-1}$ . The cross section for coherent J/ψ production is presented in six rapidity bins. The results are compared with theoretical models for coherent J/ψ photoproduction. These comparisons indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of ψ′ to J/ψ coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons

Measurement of charged jet cross section in pppp collisions at s=5.02{\sqrt{s}=5.02} TeV

International audienceThe cross section of jets reconstructed from charged particles is measured in the transverse momentum range of 5<pT<100  GeV/c in pp collisions at the center-of-mass energy of s=5.02  TeV with the ALICE detector. The jets are reconstructed using the anti-kT algorithm with resolution parameters R=0.2, 0.3, 0.4, and 0.6 in the pseudorapidity range |η|<0.9-R. The charged jet cross sections are compared with the leading-order (LO) and to next-to-leading-order (NLO) perturbative quantum chromodynamics (pQCD) calculations. It is found that the NLO calculations agree better with the measurements. The cross section ratios for different resolution parameters are also measured. These ratios increase from low pT to high pT and saturate at high pT, indicating that jet collimation is larger at high pT than at low pT. These results provide a precision test of pQCD predictions and serve as a baseline for the measurement in Pb-Pb collisions at the same energy to quantify the effects of the hot and dense medium created in heavy-ion collisions at the LHC

Long- and short-range correlations and their event-scale dependence in high-multiplicity pp collisions at s=13\boldsymbol{\sqrt{{\textit s}}}=13 TeV

Two-particle angular correlations are measured in high-multiplicity proton-proton collisions at $\sqrt{s}$ = 13 TeV by the ALICE Collaboration. The yields of particle pairs at short-(∆η ∼ 0) and long-range (1.6 < |∆η| < 1.8) in pseudorapidity are extracted on the near-side (∆φ ∼ 0). They are reported as a function of transverse momentum (p$_{T}$) in the range 1 < p$_{T}$< 4 GeV/c. Furthermore, the event-scale dependence is studied for the first time by requiring the presence of high-p$_{T}$ leading particles or jets for varying p$_{T}$ thresholds. The results demonstrate that the long-range “ridge” yield, possibly related to the collective behavior of the system, is present in events with high-p$_{T}$ processes as well. The magnitudes of the short- and long-range yields are found to grow with the event scale. The results are compared to EPOS LHC and PYTHIA 8 calculations, with and without string-shoving interactions. It is found that while both models describe the qualitative trends in the data, calculations from EPOS LHC show a better quantitative agreement for the p$_{T}$ dependency, while overestimating the event-scale dependency