Vector boson and charmonia measurements in pp+Pb collisions with ATLAS

The production of electroweak bosons ($Z,\gamma$ and $W$) and charmonia is sensitive to the initial-state geometry of heavy-ion collisions and to the parton distribution function with its potential nuclear modification. Since their leptonic decay products do not interact strongly, their kinematics are unmodified by the strongly interacting medium, which can be created in a heavy-ion collision. We report on the latest results of the ATLAS Collaboration on electroweak boson and charmonia production in $p$+Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. Production yields of $Z$ and $W$ bosons are presented as a function of (pseudo-)rapidity in different centrality bins. The forward-backward ratio of J/$\psi$ is shown as a function of transverse momentum and center-of-mass rapidity.Comment: 5 pages, 7 figures, Proceedings of XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS 2016), DESY Hamburg, Germany, 11-15 April, 201

Low-mass dielectron measurement in pp and Pb--Pb collisions in ALICE

We report on the first dielectron measurement in pp collisons at $\sqrt{s} = 7$ TeV with the ALICE detector system. The results are compared to the expected hadronic sources. The hadronic cocktail agrees to the measured dielectron continuum within statistical and systematic uncertainties. The status of the dielectron measurement in Pb--Pb collisions at {$\sqrt{s_{NN}}=2.76$} TeV is addressed.Comment: 4 pages, 7 figures, Proceedings for Hot Quarks 2012 workshop (October 14-20, 2012, Copamarina, Puerto Rico

Dielectron measurements in pp, p-Pb and Pb-Pb collisions with ALICE at the LHC

Electromagnetic probes are excellent messengers from the hot and dense medium created in high-energy heavy-ion collisions. Since leptons do not interact strongly, their spectra reflect the entire space-time evolution of the collision. The surrounding medium can lead to modifications of the dielectron production with respect to the vacuum rate. To quantify modifications in heavy-ion collisions, measurements in pp collisions serve as a reference, while the analysis of p-A collisions allows for the disentanglement of cold nuclear matter effects from those of the hot and dense medium. In this proceedings, dielectron measurements with the ALICE central barrel detectors are presented. The invariant mass distributions in the range $0<m_{ee}<3$ GeV/$c^{2}$ are compared to the expected yields from hadronic sources for pp collisions at $\sqrt{s}=7$ TeV, and for p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. The cross section of direct photons measured via virtual photons in pp collisions is compared to predictions from NLO pQCD calculations as a function of the transverse momentum. The status of the analysis of Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV is presented.Comment: 4 pages, 8 figures, Proceedings of the "Quark Matter 2014 Conference", XXIV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, Darmstadt, May 19-24 201

Towards electron transport measurements in chemically modified graphene: The effect of a solvent

Chemical functionalization of graphene modifies the local electron density of the carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice. However, not only chemistry, in this case diazonium chemistry, has an effect on the electron transport. Latter is also influenced by defects and dopants resulting from different processing steps. Here, we show that solvents used in the chemical reaction process change the transport properties. In more detail, the investigated combination of isopropanol and heating treatment reduces the doping concentration and significantly increases the mobility of graphene. Furthermore, the isopropanol treatment alone increases the concentration of dopants and introduces an asymmetry between electron and hole transport which might be difficult to distinguish from the effect of functionalization. The results shown in this work demand a closer look on the influence of solvents used for chemical modification in order to understand their influence