Measuring the collective flow with jets

In nucleus-nucleus collisions, high-p(T) partons interact with a dense medium, which possesses strong collective flow components. Here, we demonstrate that the resulting medium-induced gluon radiation does not depend solely on the energy density of the medium, but also on the collective flow. Both components can be disentangled by the measurement of particle production associated with high-p(T) trigger particles, jetlike correlations, and jets. In particular, we show that flow effects lead to a characteristic breaking of the rotational symmetry of the average jet energy and jet multiplicity distribution in the eta x phi plane. We argue that data on the medium-induced broadening of jetlike particle correlations in Au + Au collisions at the Relativistic Heavy-Ion Collider may provide evidence for a significant distortion of parton fragmentation due to the longitudinal collective flow.     

Expedient construction of the vibsanin E core without the use of protecting groups

[reaction: see text] The tricyclic core of vibsanin E was constructed without the use of a protecting group in six steps. The El Ga?ed Baylis-Hillman variant was key to allowing the Br?nsted acid induced tandem cyclization forming rings B and C in one operation.     

Reconstructing the freeze-out state in Pb+Pb collisions at 158 <Emphasis Type="Italic">A</Emphasis>GeV/<Emphasis Type="Italic">c</Emphasis><Superscript>a</Superscript>

For a class of analytical parametrizations of the freeze-out state of relativistic heavy ion collisions, we perform a simultaneous analysis of the single-particle m _⊥-spectra and two-particle Bose-Einstein correlations measured in central Pb+Pb collisions at the CERN SPS. The analysis includes a full model parameter scan with χ² confidence levels. A comparison of different transverse density profiles for the particle emission region allows for a quantitative discussion of possible model dependencies of the results. Our fit results suggest a low thermal freeze-out temperature T≈95±15 MeV and a large average transverse flow velocity \(\bar v_ \bot \approx 0.55 \pm 0.07\). Moreover, the fit favours a box-shaped transverse density profile over a Gaussian one. We discuss the origins and the consequences of these results in detail. In order to reproduce the measured pion multiplicity our model requires a positive pion chemical potential. A study of the pion phase-space density indicates μ_π≈60 MeV for T=100 MeV.     

Thermal analysis of palygorskite

Slickensides and fissures in a fresh outcrop of silicified limestones at the Bürgenstock (Switzerland) contained palygorskite. According to TG, DTA and heating X-ray experiments, dehydration of the palygorskite took place in four steps. Each step clearly showed an alteration in the unit cell dimensions. Exothermic reactions which occur at higher temperatures resulted in the formation of a Mg-Al- silicate high phase together with some clinoenstatite and the formation of β- cristobalite with some cordierite, respectively.     

A computation of the eighth Dedekind number

We compute the eighth Dedekind number, or the number of monotone collections of subsets of a set with eight elements. The number obtained is 56, 130, 437, 228, 687, 557, 907, 788.Work done while the author was with IDA-CCR, Princeton, New Jersey.     

Reference materials for thermogravimetry

The thermobalances available commercially have a wide range of heater-sample-temperature sensor relationships. Because of the differences, relating data from one apparatus to another has been imprecise. The International Confederation for Thermal Analysis has certified a set of magnetic reference materials for thermogravimetry. Analysis of the test data from eighteen instruments shows that, whereas data from several models of a single instrument show spans of measured temperatures from 3–15°, the spans for all instruments were 17–39°. The differences are systematic, not only between balance types but also for the same model of instrument in different laboratories. The use of these certified reference materials enables correlation between instruments.

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Zusammenfassung Die handelsüblichen Thermowaagen verfügen über eine breite Skala von Heizkörper-Probe-Temperaturfühler-Beziehungen. Wegen dieser Unterschiede waren die Angaben von einem Gerät zum anderen ungenau. Die Internationale Konföderation für Thermoanalyse hat eine Reihe magnetischer Referenzsubstanzen für die Thermogravimetrie bestätigt. Die Analyse der Prüfdaten von achtzehn Geräten zeigt, daß während die Angaben verschiedener Modelle in einem einzigen Instrument eine Spanne gemessener Temperaturen von 3 bis 15° zeigen, die Spannen für sämtliche Instrumente 17 bis 39° betragen. Die Differenzen sind systematisch, nicht nur zwischen Waagentypen, sondern auch für dasselbe Gerätemodell in verschiedenen Laboratorien. Der Gebrauch dieser geeichten Referenzsubstanzen gestattet die Korrelation zwischen Geräten.

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Résumé Les thermobalances en vente ont une large gamme de dispositions respectives de l'ensemble chauffage — échantillon — détecteur de température. A cause de ces différences le rapprochement des données fournies d'un appareil à l'autre est imprécis. Le Confédération Internationale d'Analyse Thermique propose une série de substances de référence magnétiques certifiées pour la thermogravimétrie. L'analyse des données d'essais fournies par dixhuit instruments montre que le données fournies par les différents modèles d'un même instrument restent comprises dans un intervalle de températures mesurées de 3 – 15° tandis que l'intervalle peut être de 17 à 39° si les valeurs fournies par tous les instruments sont prises en compte. Les différences sont systématiques, non seulement entre les différents types de balances, mais aussi pour le même modèle d'instrument dans des laboratoires différents. L'utilisation de ces substances de référence certifiées permet de corréler les divers instruments.

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— — . , , , . . , 3–15°, 17–39°. , . , , .

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Presented at the 6th ICTA Conference Bayreuth, G. F. R., 1980.     

A note on measure-valued solutions to the full Euler system

Applications of Mathematics - We construct two particular solutions of the full Euler system which emanate from the same initial data. Our aim is to show that the convex combination of these two...     

The calcination of limestone — Studies on the past, the presence and the future of a crucial industrial process

The calcination of limestone is one of the oldest technical processes and it is still of actual interest. Very early calcitic mortars from Turkey have been investigated and compared with materials of other early civilisations i.e. with Egyptian mortars containing gypsum as well as medieval dolomite-based mortars from alpine regions. Contemporary calcination procedures, in particular the cement production, range among the most important global industrial processes causing non neglectable environmental problems. Sustainable, solar energy assisted calcination technologies and the conversion of product CO₂ into useful commodities are discussed.The authors like to thank Prof. K. von Salis Perch-Nielson, Institute of Geology, ETH Zürich, for assistance in sedimentological investigations.