Refine
Year of publication
Document Type
- Article (2040)
- Preprint (1436)
- Doctoral Thesis (597)
- Conference Proceeding (249)
- diplomthesis (100)
- Bachelor Thesis (75)
- Master's Thesis (61)
- Contribution to a Periodical (46)
- Diploma Thesis (34)
- Book (33)
Keywords
- Kollisionen schwerer Ionen (47)
- heavy ion collisions (44)
- LHC (27)
- Quark-Gluon-Plasma (25)
- Heavy Ion Experiments (21)
- BESIII (19)
- equation of state (19)
- quark-gluon plasma (19)
- Relativistic heavy-ion collisions (18)
- QCD (16)
Institute
- Physik (4766) (remove)
Zur Unterstützung von Lehrkräften bei der Auswahl eines Sachunterrichtsschulbuchs im Hinblick auf die didaktische Aufbereitung physikalischer Themen wurde ein bereits bestehendes und in der Schweiz eingesetztes Schulbuchraster weiterentwickelt. Die ergänzenden Bewertungskriterien berücksichtigen, inwieweit die Schulbücher physikalische Inhalte in einer Weise präsentieren, dass a) häufige Präkonzepte der Schülerinnen und Schüler aufgegriffen, b) Inhalte strukturiert dargestellt werden, c) multiple externe Repräsentationen zum Einsatz kommen, d) Selbsterklärungen angeregt wie auch e) offene Schülerexperimente angeboten werden. Zudem sollten f) für die Lehrkräfte Zusatzmaterialen mit fachwissenschaftlichen und fachdidaktischen Erläuterungen zur Verfügungen stehen. Ergänzende Erläuterungen der Rasterkriterien sollen eine möglichst objektive Beurteilung unterstützen. Anhand dieses weiterentwickelten Rasters wurden exemplarisch die 2017 in Hessen zugelassenen Sachunterrichtsschulbücher analysiert.
In der vorliegenden Arbeit wurden zeitaufgelöste optische und magneto-optische Untersuchungen an den halb-metallischen gemischtvalenten Manganatverbindungen La0.67Ca0.33MnO3 und Nd0.7Sr0.3MnO3 durchgeführt, die wichtige Informationen über die nach der optischen Anregung ablaufenden Relaxationsprozesse lieferten. Dabei wird das zu untersuchende Material mittels eines intensitätsstarken ultrakurzen Lichtpuls angeregt. Die dadurch erzeugten Änderungen in der komplexen dielektrischen Funktion der Probe tastet man mittels eines zweiten intensitätsschwächeren ultrakurzen Lichtpuls ab. Durch eine variable Weglängendifferenz zwischen den optischen Wegen des Anregeund des Abtastpulses erzeugt man eine variable Zeitverzögerung und kann damit die Änderungen in der dielektrischen Funktion zeitaufgelöst untersuchen....
An overview is given on the experimental study of physics with relativistic heavy-ion collisions, with emphasis on recent measurements at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC). The focus here is laid on p–Pb collisions at the LHC and the corresponding d–Au measurements at RHIC. The topics touched are “collectivity and approach to equilibrium”, “high pT and jets”, “heavy flavour and electroweak bosons” and “search for exotic objects”.
Nonequilibrium models (three-fluid hydrodynamics, UrQMD, and quark molecular dynamics) are used to discuss the uniqueness of often proposed experimental signatures for quark matter formation in relativistic heavy ion collisions from the SPS via RHIC to LHC. It is demonstrated that these models - although they do treat the most interesting early phase of the collisions quite differently (thermalizing QGP vs. coherent color fields with virtual particles) -- all yield a reasonable agreement with a large variety of the available heavy ion data. Hadron/hyperon yields, including J/Psi meson production/suppression, strange matter formation, dileptons, and directed flow (bounce-off and squeeze-out) are investigated. Observations of interesting phenomena in dense matter are reported. However, we emphasize the need for systematic future measurements to search for simultaneous irregularities in the excitation functions of several observables in order to come close to pinning the properties of hot, dense QCD matter from data. The role of future experiments with the STAR and ALICE detectors is pointed out.
This a review of the present status of heavy-ion collisions at intermediate energies. The main goal of heavy-ion physics in this energy regime is to shed some light on the nuclear equation of state (EOS), hence we present the basic concept of the EOS in nuclear matter as well as of nuclear shock waves which provide the key mechanism for the compression of nuclear matter. The main part of this article is devoted to the models currently used for describing heavy-ion reactions theoretically and to the observables useful for extracting information about the EOS from experiments. A detailed discussion of the flow effects with a broad comparison with the avaible data is presented. The many-body aspects of such reactions are investigated via the multifragmentation break up of excited nuclear systems and a comparison of model calculations with the most recent multifragmentation experiments is presented.
Clathrates are candidate materials for thermoelectric applications because of a number of unique properties. The clathrate I phases in the Ba-Ni-Ge ternary system allow controlled variation of the charge carrier concentration by adjusting the Ni content. Depending on the Ni content, the physical properties vary from metal-like to insulator-like and show a transition from p-type to n-type conduction. Here we present first results on the characterization of millimeter-sized single crystals grown by the Bridgman technique. Single crystals with a composition of Ba8Ni3.5Ge42.1h0.4 show metallic behavior (dp/dT > 0) albeit with high resistivity at room temperature [p (300 K) = 1 mOhm cm]. The charge carrier concentration at 300 K, as determined from Hall-effect measurements, is 2.3 e-/unit cell. The dimensionless thermoelectric figure of merit estimated at 680 K is ZT ~ 0.2. Keywords Clathrates - thermoelectric material - intermetallic compound - nickel
An excess of J/ψ yield at very low transverse momentum (pT<0.3 GeV/c), originating from coherent photoproduction, is observed in peripheral and semicentral hadronic Pb−Pb collisions at a center-of-mass energy per nucleon pair of √sNN=5.02 TeV. The measurement is performed with the ALICE detector via the dimuon decay channel at forward rapidity (2.5<y<4). The nuclear modification factor at very low pT and the coherent photoproduction cross section are measured as a function of centrality down to the 10% most central collisions. These results extend the previous study at √sNN=2.76 TeV, confirming the clear excess over hadronic production in the pT range 0−0.3 GeV/c and the centrality range 70−90%, and establishing an excess with a significance greater than 5σ also in the 50−70% and 30−50% centrality ranges. The results are compared with earlier measurements at √sNN=2.76 TeV and with different theoretical predictions aiming at describing how coherent photoproduction occurs in hadronic interactions with nuclear overlap.
An excess of J/ψ yield at very low transverse momentum (pT<0.3 GeV/c), originating from coherent photoproduction, is observed in peripheral and semicentral hadronic Pb–Pb collisions at a center-of-mass energy per nucleon pair of sNN=5.02 TeV. The measurement is performed with the ALICE detector via the dimuon decay channel at forward rapidity (2.5<y<4). The nuclear modification factor at very low pT and the coherent photoproduction cross section are measured as a function of centrality down to the 10% most central collisions. These results extend the previous study at sNN=2.76 TeV, confirming the clear excess over hadronic production in the pT range 0−0.3 GeV/c and the centrality range 70–90%, and establishing an excess with a significance greater than 5σ also in the 50–70% and 30–50% centrality ranges. The results are compared with earlier measurements at sNN=2.76 TeV and with different theoretical predictions aiming at describing how coherent photoproduction occurs in hadronic interactions with nuclear overlap.
An excess of J/ψ yield at very low transverse momentum (pT<0.3 GeV/c), originating from coherent photoproduction, is observed in peripheral and semicentral hadronic Pb−Pb collisions at a center-of-mass energy per nucleon pair of sNN−−−√=5.02 TeV. The measurement is performed with the ALICE detector via the dimuon decay channel at forward rapidity (2.5<y<4). The nuclear modification factor at very low pT and the coherent photoproduction cross section are measured as a function of centrality down to the 10% most central collisions. These results extend the previous study at sNN−−−√=2.76 TeV, confirming the clear excess over hadronic production in the pT range 0−0.3 GeV/c and the centrality range 70−90%, and establishing an excess with a significance greater than 5σ also in the 50−70% and 30−50% centrality ranges. The results are compared with earlier measurements at sNN−−−√=2.76 TeV and with different theoretical predictions aiming at describing how coherent photoproduction occurs in hadronic interactions with nuclear overlap.