Dynamical and thermal aspects of relativistic heavy-ion collisions

Within a covariant BUU-approach we simulate heavyion collisions at various bombarding energies from 400 MeV/u to 1 GeV/u. We evaluate locally the energymomentum tensorT ^v (x), and extract pressures, energydensities and temperatures. The connection of these thermodynamical quantities to experimental observables and their sensitivity to the equation of state is discussed. Furthermore, we investigate the question of local equilibration and evaluate the entropy produced in these reactions.Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday. Work supported by BMFT and GSI Darmstadt     

Buffons Nadelproblem und verwandte probleme behandelt mit der Theorie der Gleichverteilung

The famous needle-problem of Buffon leads — as is well known — to a method to approximate with probability 1 with empirical tests. In this article, the value of approximation is treated in the case when the discrepancy of the basic random sequence is known. Some generalizations of the problem are also considered.     

Influence of surface structure on surface analytical statements

The influence of surface structure of technical materials on results and statements of surface analytical methods has been investigated. Especially surface roughness as a typical property of rolled products has been observed. For this purpose samples of steel (technical surface, roughness up to 5 m) and silicon wafers (polished surface) have been analyzed by SNMS and GDOS in order to get information about changes of the surface roughness as function of the sputtering time and their influence on the statements about the depth profiles obtained.     

Simultaneous determination of hydrogen as its iodine equivalent and of nitrogen by a volumetric method

Summary The method developed for simultaneous determination of hydrogen (by means of an equivalent amount of iodine) and of nitrogen by a volumetric method, is based on a flash combustion technique in a stream of CO₂ (100 ml/min) with controlled addition of O₂ (20%). Hydrogen is determined by conversion of water into hydrogen chloride on anhydrous magnesium chloride heated at 600–650° C, and reaction of the hydrogen chloride with Ag₂OI₂ at 220° C to yield iodine, which is collected on silver and weighed. The precision of the determination of hydrogen is excellent, the standard deviation being 0.008–0.017% abs., about a tenth of that obtained by the classical methods. The error in the determination of hydrogen was ±0.006% abs.

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Gleichzeitige Bestimmung von Wasserstoff als dessen Jodäquivalent und von Stickstoff auf volumetrischem Wege

Zusammenfassung Die entwickelte Methode zur gleichzeitigen Bestimmung von Wasserstoff in Form seines Jodäquivalents und von Stickstoff auf gasvolumetrischem Wege beruht auf der Entflammungsmineralisation im CO₂-Strom (100 cm³/min) mit kontrolliertem Zusatz von O₂ (20%). Der Gasstrom wird zusätzlich über P₂O₅ getrocknet. Die dem Wasserstoff äquivalente Jodmenge wird an metallischem Silber gebunden und gravimetrisch bestimmt, wobei Wasser bei 600–650° C mit Magnesiumchlorid in Chlorwasserstoff übergeführt wird, der nachfolgend bei 220° C mit Ag₂Oj₂ zu Jod umgesetzt wird. Für Verbindungen, die neben C, H, N und O auch Br, Cl, P und S enthalten, werden Wasserstoffresultate mit hoher Präzision erzielt:s _H beträgt 0,008 bis 0,017% absolut und ist etwa 10mal kleiner als bei den üblichen, klassischen Methoden. Die Genauigkeit der Wasserstoffbestimmung entspricht einem mittleren Fehler=±0,006% absolut. Die Resultate für den Wasserstoff und Stickstoff verlangen eine Blindwertkorrektur.

     

Differential thermal analysis - evolved gas analysis of synthetic goethite

Samples of synthetic goethite have been studied by combined DTA-EGA. The total CO₂ content of the samples ranged between 1.0 and 2.7 %wt. The origin of the evolved CO₂ is discussed and it is proposed that the samples contain CO₂ as surface complexes and incorporated in the crystal structure.