Beta-delayed two-proton decay of39Ti

The beta-delayed two-proton decay of theT _z =–5/2 nuclide³⁹Ti has been observed. The³⁹Sc isobaric analog state has been calculated to lie at 8.82 MeV using the measured two-proton sum energy of 4750±40 keV for its decay to the³⁷K ground state. Combining this excitation energy with a Coulomb displacement energy calculation has lowered the energy available for ground state two-proton emission of³⁹Ti from 760 to 530 keV.This work was supported by Director, Office of Energy Research, Division of Nuclear Physics of the Office of High Energy and Nuclear Physics of the U.S. Depeartment of Energy under Contracts DE-AC03-76SF00098 with Lawrence Berkeley Laboratory, DE-AC02-76CH00016 with Brookhaven National Laboratory and DE-AC06-76RL0 1830 with Pacific Northwest Laboratories.     

Measurement of excitation functions in the reactions 197Au(11C, xn)208-xAt using a radioactive 11C beam

A light-element radioactive ion-beam capability has been developed at the LBNL 88-Inch Cyclotron. The system is based on the coupled-cyclotrons method and utilizes short-lived species, e.g., 11C, 14O, 13N produced by (p,n) and (p,alpha) reactions at the LBNL Biomedical Isotope Facility Cyclotron. In a first experiment, 197Au(11C,xn)208-xAt excitation functions have been measured for energies ranging from the Coulomb barrier up to 110 MeV using a beam of 11C with intensities up to (1-2)x10(8) ions/sec on target. The results of this experiment are compared to measurements of 197Au(12C, xn)209-xAt excitation functions.     

Computer Simulations of the Formation of Bile Salt Micelles and Bile Salt/DPPC Mixed Micelles in Aqueous Solutions

Brownian dynamics simulations for a coarse-grained model have been performed to study the formation of micelles from bile salts and mixed micelles with dipalmitoyl-phosphatidylcholine (DPPC) in aqueous solutions. The particular association behavior of bile salts as facial surfactants was shown to be caused by their special molecular architecture with a hydrophilic and a hydrophobic side. The experimentally observed smooth transition into the micellar region with increasing concentration is reproduced. Micelle size distributions have been evaluated at different bile salt concentrations. Typical structures of pure bile salt micelles could be identified. The composition and the structure of mixed micelles have been studied in their dependence on the bile salt/lipid concentration ratio in the aqueous solution. We have found that the bile salt fraction in the mixed micelles increases considerably with increasing bile salt/lipid concentration ratio and decreasing micelle size. The structural and thermodynamic features of micelle formation in the aqueous bile salt solutions with DPPC, which we have studied with the coarse-grained model, are in good qualitative agreement with experimental findings.     

Effects of the hyperfine interactions on the decay of the collective nuclear excited states in α-hematite

In this paper the time dependence of the coherent decay of nuclear excited state in an α-⁵⁷Fe₂O₃ single crystal is presented. The experiment was carried out in diffraction geometry. A highly monochromatized and collimated beam of synchrotron radiation was used for the excitation of nuclear levels. Quantum beat spectra taken below and above the (7, 7, 7) pure nucleation reflection of hemative show a characteristic pattern corresponding to the magnetic an quadrupole hyperfine interactions. This work was performed under the auspices of the U.S. Department of Energy under Contract No. DE-AC02-76CH00016.     

Two-phase electrohydrodynamic simulations using a volume-of-fluid approach: A comment

This comment refers to the article of Tomar et al. [1], which presents a numerical methodology of a continuum surface force formulation for simulating two-phase electrohydrodynamic flows. The present work shows, that due to the diffusive character of the Laplacian equation (? · (??₀E) = 0) with discontinuous physical properties (?(x, y, z)), different averaging methods (arithmetic and harmonic) for the fluid property in the transition region have to be applied. The correct choice of the averaging method depends on the orientation of the flux to the interface.An additional improvement is made by calculating the electric displacement D at the cell faces. This leads to a numerical solution independent of the spatial resolution as well as of the interfacial smearing. Simulation results of two different test cases show that the error of the numerical solution is in the order of machine precision.     

Germanium

125 years ago, on February 6, 1886, Clemens Winkler discovered the new chemical element “Germanium”. Hence, the chemist on the Mining Academy of Freiberg (Saxony) confirmed also the theory from the Periodic Table of the Elements. The anniversary should be a sufficient motivation to remember this great scientific achievement with its interesting details.