Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES

We present measurements of exclusive ensuremathπ+,0 and η production in pp reactions at 1.25GeV and 2.2GeV beam kinetic energy in hadron and dielectron channels. In the case of π+ and π0 , high-statistics invariant-mass and angular distributions are obtained within the HADES acceptance as well as acceptance-corrected distributions, which are compared to a resonance model. The sensitivity of the data to the yield and production angular distribution of Δ (1232) and higher-lying baryon resonances is shown, and an improved parameterization is proposed. The extracted cross-sections are of special interest in the case of pp → pp η , since controversial data exist at 2.0GeV; we find \ensuremathσ=0.142±0.022 mb. Using the dielectron channels, the π0 and η Dalitz decay signals are reconstructed with yields fully consistent with the hadronic channels. The electron invariant masses and acceptance-corrected helicity angle distributions are found in good agreement with model predictions

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

Dielectron analysis in p - p collisions at 3.5 GeV with the HADES spectrometer : omega-meson line shape and a new electronics readout for the Multi-wire Drift Chambers

The HADES (High Acceptance DiElectron Spectrometer) is an experimental apparatus installed at the heavy-ion synchrotron SIS-18 at GSI, Darmstadt. The main physics motivation of the HADES experiment is the measurement of e+e− pairs in the invariant-mass range up to 1 GeV/c2 in heavy-ion collisions as well as in pion and proton-induced reactions. The HADES physics program is focused on in-medium properties of the light vector mesons ρ(770), ω(783) and φ(1020), which decay with a small branching ratio into dileptons. Dileptons are penetrating probes which allow to study the in-medium properties of hadrons. However, in heavy-ion collisions, the measurement of such lepton pairs is difficult because they are rare and have a very large combinatorial background. Recently, HADES has been upgraded with new detectors and new electronics in order to handle higher intensity beams and reactions with heavy nuclei up to Au. HADES will continue for a few more years its rich physics program at its current place at SIS-18 and then move to the upcoming international Facility for Antiproton and Ion Research (FAIR) accelerator complex. In this context the physics results presented in this work are important prerequisites for the investigation of in-medium vector meson properties in p + A and A+A collisions. This work consists of five chapters. The first chapter introduces the physics motivation and a review of recent physics results. In the second chapter, the HADES spectrometer is described and its sub-detectors are presented. Chapter three deals with the issue of lepton identification and the reconstruction of the dielectron spectra in p + p collisions is presented. Here, two reactions are characterized: inclusive and exclusive dilepton production reactions. From the spectra obtained, the corresponding cross sections are presented with the respective statistical and systematical errors. A comparison with theoretical models is included as well. Conclusions are given in chapter four. The final part of this work is dedicated to the HADES upgrade, whose goal is among others the achievement of a reliable and fast data acquisition of the Multiwire Drift Chambers (MDCs). Chapter five presents my contribution to this successful project during the three years of my stay at GSI.HADES (High Acceptance Di-Electron Spectrometer) ist ein hochauflösendes Dielektronenspektrometer, das am Schwerionen-Synchroton(SIS-18) an der Gesellschaft für Schwerionenforschung (GSI) in Darmstadt aufgebaut wurde. Die primäre physikalische Motivation des Experiments ist die Messung von e+e− Paare im invarianten Massenbereich bis 1 GeV/c2, sowohl in pion- und protoninduzierten Reaktionen, als auch in Schwerionenkollisionen. Schwerpunkt des HADES-Physik Programms ist die Erforschung von in- Medium Eigenschaften der leichten Vektormesonen ρ(770), ω(783) and φ(1020). Dileptonen sind ”penetrating probes”, die das Studium der Eigenschaften von Hadronen in Kernmaterie möglich machen. Allerdings ist die Messung dieser Dileptonenpaare schwierig, da sie selten sind und einen sehr grossen kombinatorischen Untergrund haben. Vor Kurzem wurde HADES mit neuen Detektoren und neuer Elektronik aufgerüstet, um bei höheren Intensitäten und Reaktionen schwererer Kerne messen zu können. Das breite physikalische Programm von HADES wird in den nächsten Jahren noch am SIS-18 statt finden, und dann am geplanten bevorstehenden international Facility for Antiproton and Ion Research (FAIR) Beschleuniger fortgesetzt werden. In diesem Zusammenhang sind die in der vorliegenden Arbeit vorgestellten physikalischen Ergebnisse wichtige Voraussetzungen für die Untersuchung der ”in-Medium” Vektormesonen Eigenschaften in p + A und A+A Kollisionen. Diese Arbeit besteht aus f¨unf Teilen. Das erste Kapitel beschreibt die zugrunde liegende physikalische Motivation und gibt eine Übersicht der bisherigen physikalischen Ergebnisse. Im Rahmen des zweiten Kapitels werden das HADES Spektrometer und die Subdetektoren beschrieben. Das dritte Kapitel behandelt die Frage der Identifikation der Leptonen und beschreibt die Rekonstruktion der Spektren der Elektronenpaare in p + p Kollisionen. Hier werden zwei Reaktionen charakterisiert: der inklusive (pp → Xω) und der exklusive (pp → ppω) Produktionsmechanismus der Dileptonen. In den erhaltenen Spektren werden die entsprechenden Wirkungsquerschnitte mit den jeweiligen statistischen und systematischen Fehlern dargestellt. Ein Vergleich mit theoretischen Modellen ist enthalten. Die Schlussfolgerungen werden im vierten Kapitel gegeben. Der letzte Teil dieser Arbeit fokussiert auf das HADES ”Upgrade” Programm, dessen Ziel unter anderem das Erreichen einer zuverlässigen und schnellen Datenerfassung der Multi-wire Drift Chambers (MDCs) ist. Das fünfte Kapitel präsentiert meinen Beitrag zu diesem erfolgreichen Projekt während der drei Jahre meiner Anwesenheit an der GSI

燒津鰹漁業に於ける船仲組織(上) - 本邦漁業に特異なる勞働組織の一例 -

We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at √sNN = 2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged onedimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with _dNch/dη_1/3. This behavior is compared to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller √sNN, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. The results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider

Resonance production in p+p, p+A and A+A collisions measured with HADES

The knowledge of baryonic resonance properties and production cross sections plays an important role for the extraction and understanding of medium modifications of mesons in hot and/or dense nuclear matter. We present and discuss systematics on dielectron and strangeness production obtained with HADES on p+p, p+A and A+A collisions in the few GeV energy regime with respect to these resonances