Production characteristics of the F meson

Inclusive cross sections of η production by e⁺e^- annihilation for c.m. energies between 4.0 and 5.0 GeV are presented. The η production is shown to be correlated with the production of a weakly decaying particle, indicating that its main source is F production. At the 4.42 GeV resonance it is correlated with a low energy photon, suggesting or production. A mass determination of the F is made at 4.42 GeV using the F → ηπ decay channel.     

Observation of the decay τ → πv

The decay of the heavy lepton τ into πv has been established using the magnetic detector PLUTO. The branching ratio is determined to be BR(τ→πv)=(9.0 ± 2.9)% with an additional systematic uncertainty of 2.5%. This value is in good agreement with the theoretical prediction.     

Eigenschaften und Parameterabhängigkeit der Temperaturverteilung und der Charakteristik eines zylindersymmetrischen Stickstoffbogens

The purpose of this work is to examine the properties and dependence upon parameters of the temperature distribution, and to ascertain the characteristic of a stationary, cylindersymmetrical nitrogen arc with negligible convection. Proceeding from the local balance of energy (the Elenbaas-Heller differential equation), the article makes known a process designed to determine the axial field strength in the arc discharge tube explicity with the aid of the boundary conditions of the temperature and the material functions. To this end, the differential equation is converted to a nonlinear integral equation. This equation can then, provided that the material functions are known and the parameters — radius of discharge tube, axis temperature, wall temperature — are established, be solved either numerically or graphically by a method analogous with the Picard's method of successive approximations. The numerical results, parameter limitations, and assumptions concerning material functions, enable the graphic and analytical relationship between temperature distribution and characteristic to be ascertained within a predetermined range of parameters. Thus we are enabled to interpret and theoretically record a few empirical beginnings and laws.     

Cumulative "roof effect" in high-resolution in vivo 31P NMR spectra of human calf muscle and the Clebsch-Gordan coefficients of ATP at 1.5 T

NMR spectra of non-weakly coupled spin systems exhibit asymmetries in line intensities known as "roof effect" in 1D spectroscopy. Due to limited spectral resolution, this effect has not been paid much attention so far in in vivo spectroscopy. But when high-quality spectra are obtained, this effect should be taken into account to explain the quantum-mechanical fine structure of the system. Adenosine 5'-triphosphate (ATP) represents a 31P spin system with multiple line splittings which are caused by J-couplings of medium strength at 1.5 T. We analyzed the ATP roof effect in vivo, especially for the beta-ATP multiplet. The intensities of its outer resonances deviate by ca. 12.5% from a symmetrical triplet. As this asymmetry reflects the transition from Paschen-Back to Zeeman effect with total spin that is largely broken up, the Clebsch-Gordan coefficients of the system can be indicated in analogy to the hyperfine structure of hydrogen. Taking the roof effect into account, the chi2 of fitting in vivo ATP resonances is reduced by ca. 9% (p<0.005).     

Turbulence investigations during ergodic divertor operation with induced 2/1 tearing mode

Within the last year of TEXTOR operation a major part of the experiments were dedicated to the interaction of the ergodized plasma edge, induced by the dynamic ergodic divertor (DED), with the core plasma. Systematic experiments are performed in the 3/1 configuration of the DED. Depending on , the DED generates a locked 2/1 mode in the plasma at a critical current in the DED coils. Different diagnostics were used to measure the plasma response in the core and edge. The investigations in this paper are focused on the measurement of density fluctuation and the analysis of the coherent-mode structure outside the q = 2 surface using O-mode poloidal correlation reflectometry. A reduction of the quasi-coherent mode amplitude and frequency is observed, caused by the 2/1 mode together with a decrease of the density scale length. Moreover, the deduced poloidal rotation velocity at the q = 3 surface changes from the electron to the ion diamagnetic drift direction with the onset of the 2/1 island. Also a reduction of the density fluctuations is observed as well as a decrease in the poloidal correlation length. From Ar-injection a delayed inward propagation of the emission maximum is observed for different Ar ionization stages when the 2/1 mode is generated.Similar experiments with a slowly rotating DED show that the steepened density gradients are spatially localized and confirm the hypothesis that the 2/1 mode is responsible for the observations.Presented at the Workshop Electric Fields Structures and Relaxation in Edge Plasmas, Nice, France, October 26–27, 2004.     

Effect of inhibitors on the catalyzed dehydration of HCO3- by copper(II) complexes re-evaluated

In a recent paper by Cheng and co-workers (Sun, Y.-J.; Zang, L. Z.; Cheng, P.; Lin, H.-K.; Yan, S.-P.; Sun, W.; Liao, D.-Z.; Jiang, Z.-H.; Shen, P.-W. Inorg. Chem. 2003, 42, 508-515), kinetic evidence for inhibitor effects of specific ligands on the catalyzed dehydration of HCO3- by copper(II) complexes of the type [Tp(Ph)]CuX (X- = OH-, N3-, and NCS-) was reported. The analysis of the kinetic data is not correct, and a re-evaluation shows that the claimed catalytic activity of the studied complexes on the dehydration reaction of bicarbonate is indeed questionable. Furthermore, the apparent inhibitor effect of specific selected ligands in the Cu(II) complexes does not seem to exist at all and is based on a wrong interpretation of the kinetic data.     

Calculation of high frequency ultrasonic signals for shear wave insonification in solid material

The goal of the theoretical part is to simulate an automatic ultrasonic inspection with contact technique shear wave probes, where the high frequency signals are captured and used to perform a reconstruction based on the synthetic aperture focusing method "SAFT". Therefore the ultrasonic probe, the scanning path and the defects are parameters in a CAD model. The scattering behavior of the defect is calculated by the Kirchhoff approximation in its elastodynamic version. The result of the simulation--the high frequency data--and the result of the SAFT-reconstructions are compared with experimental results on a steel test block with side drilled and flat bottom holes. The model is validated by the experiment. One of the applications of the model is to identify multiple reflections.     

Universal pion freeze-out in heavy-ion collisions

Based on an evaluation of data on pion interferometry and on particle yields at midrapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda(f) reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from the Alternating Gradient Synchrotron to the Relativistic Heavy Ion Collider.