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31.
R. Hempelmann C. J. Carlile D. Beyer Ch. Kaps 《Zeitschrift für Physik B Condensed Matter》1994,95(1):49-53
Using pulsed neutrons of 19.8 Å wavelength a quasielastic line broadening as low as 0.03 eV (FWHM) has been observed due to Na+ diffusion in the glass Na2O·2SiO2. From the linewidths a Na+ self-diffusion coefficient of 3.1·10–8 cm2/s at 420°C was obtained in excellent agreement with the diffusion coefficient determined for the same sample batch using22Na radioactive tracers. The experimental Q dependence of the quasielasic linewidths gives a hint for deviations from a purely random walk in an ionic glass. 相似文献
32.
S. Czajkowski M. Bernas P. Armbruster H. Geissel C. Kozhuharov G. Münzenberg D. Vieira Ph. Dessagne Ch. Miehe E. Hanelt G. Audi J. K. P. Lee 《Zeitschrift für Physik A Hadrons and Nuclei》1994,348(4):267-272
Neutron-rich Co and Fe isotopes produced by86Kr projectile fragmentation at 500 MeV/u were separated and identified using the fragment separator (FrS) in a bunched energy mode.66Co and65Fe ions were selectively implanted in a double PIN-diode array where the-decay signals were measured. The half-lives were deduced from time correlations between implantation and-decay signals. The remeasurement of the66Co half-life confirms the isotope identification. The value of the65Fe half-life was found to be 0.45±0.15 s. 相似文献
33.
Morenzoni E. Birke M. Hofer A. Kottmann F. Litterst J. Matthias B. Meyberg M. Niedermayer Ch. Prokscha Th. Schatz G. Wutzke Th. 《Hyperfine Interactions》1996,97(1):395-406
During the last few decades, a variety of methods has been developed which makes use of polarized positive muons as a microscopic probe of the magnetic properties of condensed matter (muon spin rotation, relaxation, resonance,SR). Until now, available beams for SR studies have delivered 100% polarized muons with energies in the MeV range, resulting in a deep penetration of the muons into the sample material under investigation. This presently limits the applications of theSR technique to the study of the bulk characteristics of matter. To be able to control the implantation depth, a very low energy beam of polarized muons is being developed at the Paul Scherrer Institute. Very slow polarized muons (kinetic energy 10 eV, polarization 90%) are obtained from the moderation of a high energy muon beam in a thin film of an appropriate condensed gas. These muons can be used as a source for a beam of tunable energy between a few tens of eV and some tens of keV. Implantation depths in the range of few to a few hundreds of nanometers can thus be achieved by varying the energy. 相似文献
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The 837 keV resonance is used for the rapid and non-destructive determination of the gradient of fluorine on the surface of metallic samples. The precise yield curve of this resonance for thick target and the experimental sensitivity of the method have been determined. With this method less than 5·10?4 μg·cm?2 fluorine content can be measured. The resolution is of the order of 1000 Å in aluminium and the concentration profiles can be measured to the depth of 1 μm. The time requirement of a surface analysis is 15–30 min, and 2–3 hrs of a gradient measurement. In addition, this method is simpler and more sensitive than the detection of the 1350 keV alpha-particles from the19F(p, αo)16O reaction. 相似文献
38.
G. Zigeuner R. Hopmann Ch. Knopp A. Fuchsgruber 《Monatshefte für Chemie / Chemical Monthly》1970,101(6):1829-1830
Dihydro-6-styryl-2(1H)-pyrimidinones react with dienophiles such as maleic anhydride in form of aDiels—Alder reaction. 相似文献
39.
I. Golicheff M. Loeuillet Ch. Engelmann 《Journal of Radioanalytical and Nuclear Chemistry》1974,22(1-2):113-129
The experimental device used is described. Excitation functions are given for an angle of observation 150° with respect to
the incident beam. The possibilities of applying these reactions to the measurement of surface lithium and fluorine concentrations
are considered. The detection limits for these two elements are shown to be 5·10−3 μg·cm−2 with protons of energy between 1,350 and 1,500 keV. The method is compared with that based on the detection of prompt γ-rays
from the reactions7Li(p, γ)8Be and19F(p, α γ)16O.
相似文献
40.
Raschig rings used as a safety mechanism, to avoid critical reactions in solutions containing radioactive materials, are usually made of borosilicate glass. Since boron is the active neutron absorbing ingredient, it is important to determine the boron content in the Raschig rings at any given time. A method has been developed to determine rapidly the boron content of borosilicate glasses. Ion exchange and potentiometric measurement are used to determine boron as the tetrafluoroborate ion. The precision of the method is ±2.0 mV. The average difference between values of a wet chemical analysis and those of the potentiometric method is 7.7%. 相似文献