Produktion von K∗−K^{*}- und Φ−\Phi- Mesonen in pp- und PbPb-Reaktionen am CERN SPS

In der vorliegenden Abhandlung wird die Produktion der Mesonen K*0(896) und Phi(1020) in pp- und PbPb-Reaktionen bei einer Schwerpunktsenergie von s 1/2=17.2GeV am CERN-SPS untersucht. In den pp-Kollisionen konnten der totale inklusive Wirkungsquerschnitt, die Longitudinal- und Transversalimpulsverteilung sowie die Abhaengigkeit der Produktionsrate vom Energieumsatz in der Kollision bestimmt werden. In den PbPb-Stoessen wurde die Abhaengigkeit der Produktionsrate von der Groesse des Stossparameters ermittelt. Der Vergleich der Produktionsraten in den beiden Kollisionssystemen liess Aussagen ueber die erhoehte Seltsamkeitsproduktion in PbPb-Stoessen zu.The topic of this thesis is the production of K*0(896)- and Phi(1020)-mesons in pp- and PbPb-collisions at a center of mass energy of s 1/2=17.2GeV at the CERN-SPS. In pp-collisions, the total inclusive cross section, the longitudinal and the transverse momentum distributions as well as the dependence of the production rates on the energy transfer in the collision were determined. In PbPb-collisions, the dependence of the meson production rates on the impact paramter was investigated. The comparison of the production rates in these two collision systems lead to statements concerning the enhanced strangeness production in PbPb-collisions.SIGLEAvailable from: http://www.iwi-iuk.org/dienste/TheO/ / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

New Results from NA49

We present recent results of the SPS experiment NA49 on production of strange particles and event-by-event fluctuations of mean $p_t$ and of charged particle ratios in central Pb+Pb collisions at various beam energies (40, 80, 158 AGeV) as well as in different collisions at 158 AGeV, going from p+p over light-ion collisions to peripheral and central Pb+Pb.Comment: 5 pages, 6 figures (in eps) talk given at XXXI International Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China URL http://ismd31.ccnu.edu.cn

Front-end electronics for drift tubes in a high-rate environment

A front-end electronics readout for drift tubes in a high-rate environment is presented. This system allows us to encode several pieces of information (leading edge time, trailing edge time, signal charge and piled-up hits from multiple tracks) into a single readout channel that is presented to the TDC. The advantage of active baseline restoration compared to bipolar signal shaping is discussed

Rate effects in high-resolution drift chambers

The impact of high counting rates on the spatial resolution of cylindrical drift tubes is investigated in detail and the results are compared with simulations. Electronics effects and space-charge effects are quantitatively analysed. A spatial resolution of $\sigma < 80\,\mu\mathrm{m}$ can be achieved even at rates as high as 1500\,Hz/cm wire length (300\,kHz per wire)

Resolution limits of drift tubes

Measurements of the drift-tube response to charged particle tracks are compared with a complete simulation. The measured resolution of typically 80\,$\mu$m agrees well with the simulation and allows the individual factors limiting the resolution such as diffusion, charge deposit fluctuations, gas gain fluctuations and signal processing to be studied. The results with respect to the dependence of the drift chamber resolution on gas gain, gas pressure and electronics parameters are reported

Dependence of Drift Tube Performance on the Anode Wire Diameter

Cylindrical pressurized drift tubes with different anode wire diameters wereoperated in a 170~GeV muon test beam. The dependences of spatialresolution, efficiency and streamer probability on the anode wirediameter were measured. The resolution measurements are compared with a simulation

Activation of Carbon-Hydrogen and Hydrogen-Hydrogen Bonds by Copper-Nitrenes: A Comparison of Density Functionality Theory with Single- and Multireference Correlation Consistent Composite Approaches

Article on a comparison of density functional theory with single- and multireference correlation consistent composite approaches (ccCA)

The Ectomycorrhizospheric Habitat of Norway Spruce and Tricholoma vaccinum: Promotion of Plant Growth and Fitness by a Rich Microorganismic Community

The contribution of the mycorrhizospheric microbes in a stand of ectomycorrhizal Norway spruce (Picea abies) featuring mycorrhiza with the basidiomycete Tricholoma vaccinum was addressed by microbiome analysis and in vitro reconstruction of microbial as well as plant-microbe interactions. The protective role of the mycorrhizal fungus with respect to pathogen attack could be validated against Botrytis cinerea and Heterobasidion annosum in co-cultures revealing reduced pathogen growth, higher survival rate of the spruce trees and reduced symptoms on needles upon symbiosis with T. vaccinum. The community structure was shown to yield a high diversity in ECM forming basidiomycetes of Thelephorales and Agaricales associated with a rich bacterial diversity dominated by Rhizobiales with the most abundant Nitrobacter winogradski (3.9%). Isolated bacteria were then used to address plant growth promoting abilities, which included production of the phytohormone indole-3-acetic acid (performed by 74% of the bacterial isolates), siderophores (22%), and phosphate mobilization (23%). Among the isolates, mycorrhiza helper bacteria (MHB) were identified, with Bacillus cereus MRZ-1 inducing hyperbranching in T. vaccinum, supporting tree germination, shoot elongation, and root formation as well as higher mycorrhization rates. Thus, a huge pool of potential MHB and fungal community with widely distributed auxin-production potential extended the ability of T. vaccinum to form ectomycorrhiza. The forest community profited from the mycorrhizal fungus T. vaccinum, with spruce survival enhanced by 33% in microcosms using soil from the native habitat. A higher fungal abundance and diversity in cases where the tree had died during the experiment, showing that decomposition of plant litter from a dead tree supported a different community. T. vaccinum thus actively structured the community of microorganisms in its habitat

Performance of Density Functional Theory for 3d Transition Metal-Containing Complexes: Utilization of the Correlation Consistent Basis Sets

Article discussing the performance of density functional theory for 3d transition metal-containing complexes and the utilization of the correlation consistent basis sets