General theory of similarity measures for library search systems

A general theory of similarity measures for library search systems is presented. It shows that once the spectral features to be used in the comparison of two spectra have been selected and their relative importance has been fixed, the characteristics of the similarity measure are fully controlled by two independent parameters. These two parameters control whether a forward or a reverse search and whether an identity, a similarity, or a classification search is conducted.     

212Th,a new isotope

The new isotope²¹²Th has been found to decay withE _α = (7.802 ±0.010) MeV andt _1/2 =(30 _?10 ⁺²⁰ ms. The decay energies of the previously observed isotopes²¹³Th and²¹⁴Th could be confirmed. The measured half-lives are in agreement with calculated values.     

Diffusion localisée de phosphore dans le silicium

Sans résumé     

Nuclear charge distribution of mass-separated isobars from thermal-neutron-induced fission of 235U

The nuclear charge distribution of fission products with mass numbers A = 90, 91, 94, 99, 100, 101 and 104 provided by the mass separator “Lohengrin” was measured. Adjacent elements in the group of the light fission products could be separated by their different energy loss in a carbon absorber. The Z-yields were found to be strongly dependent on the kinetic energy of the fission products. The widths of the nuclear charge distributions are very small, in general, and strongly dependent on A as well as on the kinetic energy. The influence of the neutron evaporation and odd-even effects are clearly detected. An asymmetric nuclear charge distribution was found for A = 104 indicating the suppression of fission fragments with Z = 43. The average nuclear charges of the fission products at their average kinetic energy are in good agreement with the results from measurements of the number of β-decays and K X-ray measurements. The average nuclear charge of the isobar A = 132 was measured at its average kinetic energy with a calibrated secondary electron detector to be Z = 51.14 ± 0.15 which is in very good agreement with the radiochemical results. Thus previous physical measurements indicating a large independent yield for the doubly magic nucleus ¹³²Sn could not be confirmed.     

Strukturaufklärung organischer Verbindungen durch computerunterstützten Vergleich spektraler Daten

A system for computer-aided identification of organic compounds by means of spectroscopic data is described. The binary coded spectral data of the unknown compounds are compared with a reference file containing NMR., IR. and Mass Spectra. A highly flexible software automatically selects the appropriate search strategy and directs the updating of the collection, thereby ensuring continuous adaption to varying needs.     

Determination of H o , G o , and S o of the interaction of ions with carrier antibiotics by computerized microcalorimetry

ΔH°, ΔG°, and ΔS° — and thereby the equilibrium constant of the interaction of carrier antibiotics with ions — are determined using a microcalorimeter on-line with a dedicated computer. Thermodynamic data of the interaction of monensin, macrotetrolides and valinomycin with sodium and potassium ions in methanol at 25°C are given.     

Momentum distributions of projectile fragments produced in the cold and hot fragmentation of relativistic136Xe and197Au projectiles

The longitudinal-momentum distributions of projectile fragments from 0.8 A GeV¹³⁶Xe and 1 A GeV¹⁹⁷Au projectiles impinging on targets of beryllium and aluminium, respectively, have been measured using the projectile-fragment separator FRS at GSI. Different momentum distributions have been found for two different classes of fragmentation processes: the abundant hot fragmentation with several nucleons evaporated from the prefragments, and the rare cold fragmentation with only protons removed from the projectile, but no nucleons evaporated. The data are compared to model calculations.This article comprises part of the Ph.D. thesis of B. Voss     

Investigation of the fusion of heavy nearly symmetric systems

Excitation functions in the vicinity of the Coulomb barrier have been measured for the formation of evaporation residues in¹⁰⁰Mo-induced fusion reactions with^{90, 92, 96}Zr,^{92, 96, 98, 100}Mo,¹⁰⁴Ru and¹¹⁰Pd as well as for the system⁹⁶Zr+⁹⁶Zr. From these data the fusion probability in central collisions was extracted covering a range of 4 orders of magnitude. At the fusion barriers expected from systematics we find that the fusion probability is suppressed by one to three orders of magnitude. It is rising very gradually at higher energies and reaches for the heaviest systems saturation only at energies as high as 30 MeV above the barrier. The observed hindrance of the fusion process increases roughly with the growing Coulomb repulsion between the collision partners, but there is also a distinct influence of their individual nuclear structure. The data are compared to the extra-push model, the surface-friction model and the diabatic fusion model. A parameterisation of the extra-push energy and its fluctuation in terms of a macroscopic quantity like the Coulomb repulsion combined with a microscopic quantity characterizing the nuclear structure is proposed. As a byproduct of this work a new alpha emitter,¹⁹¹Po, could be identified. Its half-life is (15.5 _–2.5 ⁺⁶ ) ms, the alpha energy is (7314±20) keV.