[en] This paper reports on a measurement of the photoproduction of ω(782) and Φ(1020) vector mesons with the SAPHIR detector at the electron accelerator facility ELSA. The incident photons were tagged in an energy range from reaction threshold up to 2.6 GeV. ω and Φ events were selected by separating their signal in the invariant mass spectrum of their decay products, i.e. in the π⁺π^-π⁰ and the K⁺K^- system, respectively. As a cross check for normalization the inclusive two and three pion production was evaluated. The results agree with earlier experiments. From the experimental data total cross sections σ_tot, differential cross sections dσ/dt as well as decay angular distributions in both, Gottfried Jackson and helicity frames, were extracted. For the ω production they show that diffractive processes play an important role as expected from higher energy data. However, at threshold s-channel resonances significantly contribute. In the region of large four-momentum transfers (vertical stroke t vertical stroke > 1 GeV²) significant deviations from t-channel exchange mechanisms are observed. The Φ production can be described mainly by diffraction, but also other t-channel exchange processes seem to contribute. (orig.)

[en] After a general presentation of the present energy situation and its future prospects, the author evokes the main directions of the electric current production policy and stresses the development of the electronuclear program. He discusses more particularly the problems of nuclear acceptance by the public as well as the revision of the regulations now in force

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[en] The alimentary solubility and behavior of neptunium-234 were studied in an artificial rumen and simulated bovine gastrointestinal fluids. Rumen juice was augmented with citrate-buffered neptunium-234 solution and allowed to incubate for 24 hours. This juice was successively converted, by the addition of bile and enzymes and adjustment of the pH, to simulate the digestive stages of the abomasum, duodenum, jejunum, and lower small intestine. Fluid samples were collected from each of these digestive stages and analyzed for soluble neptunium-234 by gamma spectrometry

[en] An artificial rumen and simulated abomasal and intestinal fluids procedure was used to study the alimentary availability of plutonium-238. When plutonium-238 was administered as plutonium nitrate, 10.1% remained soluble following the artificial rumen incubation period and 15.3% following the abomasal period; 30.1% and 32.7% remained soluble when the fluid was held at pH 4 and 5, respectively, during the duodenal phase. The solubility increased to 60.1% following the addition of bile and enzymes with adjustment of the pH to 6 to simulate the jejunum. The increase in plutonium solubility in the simulated jejunal fluid was found to be due to the presence of bile. Plutonium administered as a citrate-buffered plutonium solution was 9.0% soluble following the rumen incubation period, 13.1% following the abomasal period, and 22.5% and 24.8% when held at pH 4 and 5, respectively, in the duodenal phase. The solubility increased to 59.6% following the addition of bile and enzymes with adjustment of the pH to 6. Plutonium administered as 0.06-μm plutonium dioxide spheres was 1.5% soluble following the rumen incubation period, 2.3% following the abomasal period, and 3.6% and 3.9% when held at pH 4 and 5, respectively, in the duodenal phase. Solubility increased to 7.4% following the addition of bile and enzymes with adjustment of the pH to 6. Rumen contents of cattle grazing on plutonium-contaminated desert vegetation at the Nevada Test Site, Area 13, were collected quarterly and incubated in simulated bovine gastrointestinal fluids to study the alimentary availability of field-deposited plutonium-238, plutonium-239, and americium-241. Results to date indicate that the highest concentrations of plutonium and americium in the rumen contents occurred during the late summer or fall

[en] One of the broader applications of synchrotron radiation has been to EXAFS studies for material structure determination, i.e., for an analysis of x-ray absorption over an extended energy region beyond a core ionization limit. Studies of the near edge structure (XANES) give a different type of information, characteristic of the local symmetry and electronic configuration of the absorbing atom. This type of information is reflected also in the x-ray emission spectra, in particular for transitions involving the valence levels. Examination of the near edge absorption or the emission spectrum does not require an instrument capable of scanning a wide energy range with high counting statistics, as does EXAFS; the needs are rather for good resolution and a reliable calibration of the energy scale. Some of the problems of near edge spectra were particularly evident in our investigation of Ru-Lβ₂₁₅ emission from Ru(NH₃)₆Cl₃. The Ru-Lβ₂₁₅ emission was measured with a laboratory Rowland circle x-ray spectrometer with a curved quartz (1010) crystal (radius = 22 inches) in a fixed position appropriate to the energy range, and a position sensitive detector which can be positioned along the Rowland circle. The Ru spectrum was excited mainly by Sn-L/sub α/ primary radiation from a Sn anode in a demountable x-ray tube operating at 13 kV and 120 mA. The resolution of the instrument in this region is 1.5 eV. An accurate calibration of the energy scale was conveniently obtained by measuring a reference x-ray emission line in the same instrumental configuration. In the present case the Pd-L/sub α/ emission line at 2838 eV was used to establish the energy scale. The energy dispersion of the instrument was determined from the Cl-K/sub β/ emission spectrum of CH₃Cl between 2810 eV and 2830 eV and Pd-Lα₁₂ and extrapolated to the energy region of the recorded emission spectrum. 6 references, 1 figure

[en] The uptake of ²³⁸Pu, ²³⁹Pu, and ²⁴¹Am by cattle through ingestion of contaminated forage at the Nevada Test Site and the Rocky Flats Plant are compared. Data are included on the solubility of ²³⁹Pu and ²⁴¹Am by bovine gastrointestinal fluids, the effects of particle size on the retention of sand in the gastrointestinal tract of ruminants, the tissue distribution of ²³⁸Pu, and ²⁴³Cm in lactating dairy cows, with emphasis on excretion in milk