Leptonic and charged kaon decay modes of the phi meson measured in heavy-ion collisions at the CERN super proton synchrotron

We report on results of a measurement of meson production in central Pb-Au collisions at E(lab) = 158A GeV. For the first time in the history of high energy heavy-ion collisions, phi mesons were reconstructed both in the K+K- and the dilepton decay channels in the same experiment. This measurement yields rapidity densities near midrapidity, from the two decay channels, of 2.05 +/- 0.14(stat) +/- 0.25(syst) and 2.04 +/- 0.49(stat) +/- 0.32(syst), respectively. The shape of the measured transverse momentum spectrum is also in close agreement in both decay channels. The data rule out a possible enhancement of the phi yield in the leptonic over the hadronic decay channel of a factor 1.6 or larger at the 95% C.L. This rules out the discrepancy reported in the literature between measurements of the hadronic and dimuon decay channels by two different experiments.     

Asymptotic cohomological functions of toric divisors

We study functions on the class group of a toric variety measuring the rates of growth of the cohomology groups of multiples of divisors. We show that these functions are piecewise polynomial with respect to finite polyhedral chamber decompositions. As applications, we express the self-intersection number of a T-Cartier divisor as a linear combination of the volumes of the bounded regions in the corresponding hyperplane arrangement and prove an asymptotic converse to Serre vanishing.     

Eine Beziehung zwischen Binomialkoeffizienten und Primzahlpotenzen

Ohne Zusammenfassung     

The membrane inclusions curvature equations

We examine a system of equations arising in biophysics whose solutions are believed to represent the stable positions of N conical proteins embedded in a cell membrane. Symmetry considerations motivate two equivalent refomulations of the system which allow the complete classification of solutions for small N<13. The occurrence of regular geometric patterns in these solutions suggests considering a simpler system, which leads to the detection of solutions for larger N up to 280. We use the most recent techniques of Gröbner bases computation for solving polynomial systems of equations.     

Macroscopic Isotope Separation of 13C by a CO2 Laser

By photochemical dissociation of the rare carbon isotope component of CHClF₂ by means of a CO₂ laser with an average power of 150 W, Q-switched at 10 kHz, we have demonstrated the separation of more than 1 mol of ¹³C, enriched to 50% (2 mol of total carbon). It is contained in about 1 mol (101 g) of the product C₂F₄. The total throughput of the starting material was 29 kg. The experiment was run day and night for 2 weeks, almost only controlled by a computer. We obtained production rates of 5 mmol/h, corresponding to about 0.5 kg ¹³C per year.     

Infrared laser-spectroscopic analysis of <Superscript>14</Superscript>NO and <Superscript>15</Superscript>NO in human breath

We report on monitoring of nitric oxide (NO) traces in human breath via infrared cavity leak-out spectroscopy. Using a CO sideband laser near 5 μm wavelength and an optical cavity with two high-reflectivity mirrors (R=99.98%), the minimum detectable absorption is 2×10⁻¹⁰ cm⁻¹ Hz^1/2. This allows for spectroscopic analysis of rare NO isotopologues with unprecedented sensitivity. Application to simultaneous online detection of ¹⁴NO and ¹⁵NO in breath samples collected in the nasal cavity is described for the first time. We achieved a noise-equivalent detection limit of 7 parts per trillion for nasal ¹⁵NO (integration time: 70 s).     

Spin polarization in 16O-induced heavy-ion reactions

The circular polarization P_γ of γ-rays from ¹⁶O-induced reactions on ²⁷Al, ⁴⁸Ti, ⁵⁸Ni and ⁶²Ni at 100 MeV incident energy has been measured in coincidence with projectile-like fragments detected at angles behind the grazing angle. The dependence of P_γ on the reaction Q-value, on the fragment atomic number and, for ¹⁶O+⁴⁸Ti, on the scattering angle was investigated.The results show that deep-inelastic (DI) collisions in these fairly light heavy-ion systems are associated with predominantly negative scattering angles. The average value of P_γ(DI) = 0.6 obtained for ¹⁶O + Ni at θ_lab= 35° is consistent with pure negative-angle scattering. The magnitude of P_γ(DI) is smaller for the two lighter systems which is interpreted as mainly arising from the increasing probability for orbiting trajectories leading to scattering angles beyond 180°Trajectory calculations within a classical friction model were performed, and the parameter dependence of the results was studied. Strong radial friction forces were found necessary to simulate the observed negative-angle cross sections.