φ production in In–In collisions at 158 A GeV

The NA60 experiment has measured muon pair production in In–In collisions at 158 AGeV at the CERN SPS. This paper presents a high statistics measurement of φ→μ μ meson production. Differential spectra, yields, mass and width are measured as a function of centrality and compared to previous measurements in other colliding systems at the same energy. The width of the rapidity distribution is found to be constant as a function of centrality, compatible with previous results. The decay muon polar angle distribution is measured in several reference frames. No evidence of polarization is found as a function of transverse momentum and centrality. The analysis of the p _T spectra shows that the φ has a small radial flow, implying a weak coupling to the medium. The T _eff parameter measured in In–In collisions suggests that the high value observed in Pb–Pb in the kaon channel is difficult to reconcile with radial flow alone. The absolute yield is compared to results in Pb–Pb collisions: though significantly smaller than measured by NA50 in the muon channel, it is found to exceed the NA49 and CERES data in the kaon channel at any centrality. The mass and width are found to be compatible with the PDG values at any centrality and at any p _T : no evidence for in-medium modifications is observed.     

Relationship between the Molecular Structure of Cyanine Dyes and the Vibrational Fine Structure of their Electronic Absorption Spectra

Vibronic sub‐bands in the electronic absorption spectra of symmetrical cyanine dyes (see picture) are attributed to the symmetric C? C valence vibration of the polymethine chain in the excited state. The ³J(H,H) coupling constants in the polymethine chain can be used to characterize the bond localization within the chain in the ground state and thus to explain the intensity distribution of the sub‐bands.

     

Combining reactive and configurational-bias Monte Carlo: confinement influence on the propene metathesis reaction system in various zeolites

In order to efficiently calculate chemical equilibria of large molecules in a confined environment the reactive Monte Carlo technique is combined with the configurational-bias Monte Carlo approach. To prove that detailed balance is fulfilled the acceptance rule for this combination of particular Monte Carlo techniques is derived in detail. Notably, by using this derivation all other acceptance rules of any Monte Carlo trial moves usually carried out in combination with the configurational-bias Monte Carlo approach can be deduced from it. As an application of the combination of reactive and configurational-bias Monte Carlo the influence of different zeolitic confinements (MFI, TON, LTL, and FER) on the reaction equilibrium and the selectivity of the propene metathesis reaction system was investigated. Compared to the bulk phase the conversion is increased significantly. The authors study this reaction system in the temperature range between 300 and 600 K, and the pressure range from 1 to 7 bars. In contrast to the bulk phase, pressure and temperature have a strong influence on the composition of the reaction mixture in confinement. At low pressures and temperatures both conversion and selectivity are highest. Furthermore, the equilibrium composition is strongly dependent on the type of zeolite. This demonstrates the important role of the host structure in catalytic systems.     

Perfect imaging through a disordered waveguide lattice

It is experimentally demonstrated that perfect imaging is possible in disordered wave guiding media, provided that the disorder is off-diagonal, i.e., that only the spacing varies randomly between the otherwise identical lattice sites. On-diagonal disorder or Kerr nonlinearity destroys the imaging.     

Selektive Bestimmung von Niob durch Extraktion des Hydroxychinolinkomplexes

Zusammenfassung Eine selektive, relativ schnell durchführbare photometrische Mikrobestimmung von Mob in Zr-Nb-Legierungen und anderen Materialien wurde ausgearbeitet. Sie beruht auf der Extraktion des Niobs mit einer Oxin/Chloroformlösung und photometrischer Messung bei 385 nm. Störende Elemente werden vor der Extraktion aus H₂O₂-haltiger Lösung mit Natronlauge ausgefällt. Die relative Genauigkeit beträgt ± 3%, die kleinste bestimmbare Menge 1 Nb/10 ml.

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Summary A selective and fairly rapid method has been worked out for the determination of micro amounts of niobium in Zr-Nb alloys and other materials. It is based on the extraction of Nb with a solution of hydroxyquinoline in chloroform and photometric measurement at 385 nm. Interfering elements are removed before the extraction by precipitation with sodium hydroxide in presence of hydrogen peroxide. The relative accuracy is ± 3%, the minimum quantity to be determined 1 Nb/10 ml.

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Für die kritische Überprüfung meiner Arbeit möchte ich Herrn Dr. H. Züst danken.     

Neue hochselektive spektralphotometrische Cyanidbestimmung durch Zerstörung des Platin-3,4-Diaminobenzoesäure-Komplexes

An accurate sensitive and simple method for the determination of cyanide was developed from the fact that cyanide interferes strongly in the determination of platinum with 3,4-diaminobenzoic acid. The influence of a great number of cations and anions was tested. Due to the high selectivity the method is especially suited for the analysis of more complex samples such as waste waters. The sensitivity of <0.02 μg CN^?/ml compares favourably with the known methods. About 30–40 samples can be analysed per day.     

Spektralphotometrische Bestimmung von schwerem Wasser in H2O/D2O-Gemischen im nahen Infrarot

Three different methods are described for the determination of D₂O in H₂O/D₂O mixtures by means of IR absorption. Wave-lengths, concentration ranges and accuracies are as follows: 2500 nm: 99–100 Mol-% D₂O, ±0.001%; 1670 nm: 0–20 Mol-% D₂O, ±0.02%; 1368 nm: 0–100% D₂O, ±0.1%. The methods are simple and rapid and have been successfully used for several years.     

Einflu? variabler18O-Gehalte auf die refraktometrische und spektralphotometrische D-Gehaltsbestimmung in Wasser

Zusammenfassung Mit Hilfe von hochangereichertem H₂ ¹⁸O und D₂ ¹⁸O wird der Einfluß des¹⁸O-Gehaltes auf einige Methoden der optischen D/H-Analyse von Wasser untersucht. Bei der refraktometrischen D-Gehaltsbestimmung entsprechen dem instrumentellen Fehler von ±0,1% D Variationen von 6 Atom-%¹⁸O in H₂O und 20%¹⁸O in D₂O.Der Einfluß auf einige spektralphotometrische D-Bestimmungsmethoden im nahen Infrarot wird anhand von Differenzspektren von D₂ ¹⁸O gegen D₂ ¹⁶O und von H₂ ¹⁸O gegen H₂ ¹⁶O ermittelt. Es werden auch geeignete Wellenlängen für minimale Störung der D-Analyse durch den¹⁸O-Gehalt angegeben und Möglichkeiten für die spektralphotometrische¹⁸O-Analyse in H₂O und D₂O diskutiert.

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Influence of varying¹⁸O contents on the refractometric and spectrophotometric D-determination in water

The influence of varying¹⁸O-contents on the D-analysis of water by some optical methods is investigated by means of highly enriched H₂ ¹⁸O and D₂ ¹⁸O. The instrumental error of ±0.1% D in the refractometric D-analysis of water was found to correspond to differences of 6 atom%¹⁸O in H₂O and 20%¹⁸O in D₂O.The sensitivity of several spectrophotometric methods of D-analysis to differences in¹⁸O content is determined on the basis of differential spectra between D₂ ¹⁸O and D₂ ¹⁶O and H₂ ¹⁸O and H₂ ¹⁶O, respectively. Wavelengths for minimum interference of¹⁸O-content with D-analysis are given and possibilities of spectrophotometric¹⁸O-analysis are discussed.