Proton-Induced Deuteron Breakup Reaction at 65 MeV: Unspecific Configurations

 Cross sections and vector-analyzing powers for four unspecific configurations of the ²H(p,pp)n breakup reaction at E ^lab _p  = 65MeV were measured in a kinematically complete experiment. Measured observables are compared with rigorous Faddeev calculations using four realistic charge-dependent interaction models, the CD Bonn, Argonne v ₁₈, Nijmegen I, and Nijmegen II potentials with or without inclusion of the Tucson-Melbourne three-nucleon force. Coulomb effects are completely omitted. A satisfactory agreement between theory and experiment has been found. There exist, however, some discrepancies between measured and calculated analyzing-power distributions in certain kinematical regions. The effects of the Tucson-Melbourne three-body force are either negligible or slightly increasing the disagreement. Received May 12, 1999; revised March 3, 2000; accepted for publication April 26, 2000     

New excited superdeformed bands in heavy Pb nuclei: Clue for an octupole softness near the N = 118 gap at large deformation

We report the identification of six new superdeformed (SD) bands in ^197,198Pb observed with the EUROBALL IV spectrometer. The results are interpreted in the framework of cranked Hartree-Fock calculations with approximate projection on the particle number by means of the Lipkin-Nogami method. A mixing between quasi-particle excitations and an octupole vibration is suggested in the two SD isotopes. We have estimated the ordering of the neutron valence orbitals and confirm indirectly a N = 118 SD gap. Received: 20 December 2000 / Accepted: 24 January 2001     

High resolution inductively coupled plasma mass spectrometry (HR-ICPMS) determination and multivariate evaluation of 10 trace elements in mussels from 7 sites in Limfjorden, Denmark

The contents of V, Cr, Co, Ni, Cu, Ga, Rb, Cd, Ba, and Pb in the soft tissue of blue mussel (Mytilus edulis) were determined by a high resolution inductively coupled plasma mass spectrometry (HR-ICPMS) method. Sample digestions were performed in closed microwave vessels using nitric acid and hydrogen peroxide. Using HR-ICPMS it is possible to resolve the analytical peaks from otherwise interfering polyatomic ions with a mass resolution setting of 4000 (Cr, Ni, Cu). The proposed method was validated using a mussel tissue reference material (NIST SRM 2974). The proposed method was applied to real samples of blue mussel from seven sites in the inlet “Limfjorden”, Denmark, and the levels of trace elements found were compared with the levels found in an earlier study. For the mussel samples large inter-regional differences in trace element concentrations in the tissues were recorded. The mussels from the different sites could be separated using principal component analysis (PCA). Comparison with the levels of trace elements in mussels found in 1982 showed that the trace elemental contamination has increased during the last 15 years. From the data obtained, mussel tissue appears to be good bio-indicator for identification of coastal areas exposed to metallic contaminants.     

Interpolation of Scattered 3D PTV Data to a Regular Grid

The velocity data obtained by many 3D measurement methods such as particle tracking velocimetry (PTV) are not regularly distributed in3D space. We revised three numerical schemes to interpolate the scattered velocity vectors to a regularly spaced grid. Additionally, two techniques were examined to smooth the resulting flow field. The different algorithms were tested for a synthetic data set based on the analytical solution of Burgers' vortex. To study the impact of measurement errors a Gaussian noise was superimposed on the exact solution. It was found that an interpolation scheme of higher order does not necessarily perform better than one of lower order. The most‘robust’ algorithm was used to process 3D PTV data, which were obtained from measurements of a separating flow in a forward facing step configuration. Information on the 3D streamlines and vortex structures was obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mixing modeling for stochastic simulations of turbulent premixed flames

The use of probability density function (PDF) methods for turbulent combustion simulations is very attractive because arbitrary finite-rate chemistry can be exactly taken into account. However, many real flames involve a variety of mixing regimes (non-premixed, partially-premixed and premixed turbulent combustion), and the development of PDF methods for partiallypremixed and premixed turbulent combustion turned out to be a very challenging task. A promising way to extend the range of applicability of PDF methods to the fast flamelet chemistry of turbulent premixed flames is described here. Simulation results of three turbulent premixed flames demonstrate the suitability of this approach. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Species-specific isotope-ratio measurements of volatile tin and antimony compounds using capillary GC–ICP–time-of-flight MS

The analytical performance of an axial inductively-coupled-plasma time-of-flight mass spectrometer (ICP–TOFMS) as a detector for fast transient chromatographic signals resulting from the coupling to capillary gas chromatography (CGC) was investigated. A cryotrapping GC–ICP–TOFMS method for the determination of volatile metal(loid) compounds (VOMs) in gases was used and the suitability of the TOF mass analyzer for multi-elemental speciation analysis and multi-isotope ratio determinations was studied in terms of accuracy and precision. Isotope ratios ¹¹⁸Sn/¹²⁰Sn and ¹²¹Sb/¹²³Sb have been determined in in-house gas standard atmospheres in Tedlar bags at two different levels (100 pg and 1 ng) for different elemental species (SnH₄, MeSnH₃, Me₂SnH₂, Me₃SnH, BuSnH₃, SbH₃, and MeSbH₂). A limitation arising from counting statistics in both detection modes could be shown. A solution containing rhodium (10 ng mL^–1) and cadmium (40 ng mL^–1) was introduced simultaneously to the GC outlet. Rhodium acts as a continuous internal standard and Cd is used for mass-bias correction (by measuring the ¹¹¹Cd/¹¹³Cd ratio). The detection system in both pulse counting and analog mode was examined. The best attainable precision was established for Me₂SnH₂ (analog mode, 12 replicates, 1 ng, RSD 0.34%, accuracy 0.31%) whereas most other species ranged between 0.4 and 0.5% RSD if higher concentrations were used. The limitations of the pulse counting system are clearly seen, with peak heights of more than 2000 counts reaching saturation (for an integration time of 100 ms), which reduces the accuracy of isotope ratio determinations. A dozen VOM could be detected in an aged landfill gas sample; several unidentified Sn compounds were present. Although their isotope ratios are within the confidence value of the standards, it is not yet clear if the acquired precision is good enough to identify isotopic fractionation of metal(loid)s through biovolatilization processes. With the precision achieved, the combination of cryotrapping GC and ICP–TOFMS is a powerful tool for monitoring volatile multi-element species in multi-tracer experiments and isotope dilution methodology. Received: 23 November 2000 / Revised: 19 February 2001 / Accepted: 24 February 2001     

Spectroscopy of Ly-α Lines at Storage Rings by Crystal Spectrometry and Absorption Edge Technique

Crystal spectrometry and absorption edge technique have the capability to overcome the gap in accuracy between experiment and theory in the strong field domain of QED. New results are presented which indicate the capacity of these methods to measure the energies of X-rays emitted by highly charged heavy ions at modern storage rings with a precision sensitive to second order corrections to the Lambshift in H-like very heavy ions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Infrared Spectra of the HAnX and H2AnX2 Molecules (An=Th and U,X=Cl and Br) in Argon Matrices Supported by Electronic Structure Calculations

Uranium and thorium hydrides are known as functional groups for ligand stabilized complexes and as isolated molecules under matrix isolation conditions. Here, the new molecular products of the reactions of laser-ablated U and Th atoms with HCl and with HBr, namely HUCl, HUBr and HThCl, HThBr, based on their mid and far infrared spectra in solid argon, are reported. The assignment of these species is based on the close agreement between observed and calculated vibrational frequencies. The H−U and U−³⁵Cl stretching modes of HUCl were observed at 1404.6 and 323.8 cm⁻¹, respectively. Using DCl instead to form DUCl gives absorption bands at 1003.1 and 314.7 cm⁻¹. The corresponding bands of HThCl are 1483.8 (H−Th) and 1058.0 (D −Th), as well as 340.3 and 335.8 cm⁻¹ (Th−³⁵Cl), respectively. HUBr is observed at 1410.6 cm⁻¹ and the BP86 computed shift from HUCl is 6.2 cm⁻¹ in excellent agreement. The U−H stretching frequency increases from 1383.1 (HUF), 1404.6 (HUCl), 1410.6 (HUBr) to 1423.6 cm⁻¹ (UH) as less electronic charge is removed from the U−H bond by the less electronegative substituent. These U−H stretching frequencies follow the Mayer bond orders calculated for the three HUX molecules. A similar trend is found for the Th counterparts. Additional absorptions are assigned to the H₂AnX₂ molecules (An=U, Th, X=Cl, Br) formed by the exothermic reaction of a second HX molecule with the above primary products.