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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 219 (1967), S. 106-113 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Zusammenfassung Mit Hilfe einer neuen Meßmethode wurde die Polarisationsspannung in Niederdruckpolyäthylen bei einer Probe von 400 μm Dicke in Abhängigkeit von der äußeren Spannung und bei verschiedenen Temperaturen in Abhängigkeit von der Polarisierungszeit gemessen. Der im Bereich zwischen 40°C und 70°C gefundene Polarisationsverlauf, bei dem die Polarisation mit der Zeit nicht stetig ansteigt, sondern ein Maximum und ein Minimum durchläuft, bevor sie den maximalen Endwert erreicht, wird durch Entladung von Ladungsträgern an einer Elektrode erklärt. Aus der Temperaturabhängigkeit des Minimums im Polarisationsverlauf wird eine Aktivierungsenergie von 0,3 eV bestimmt, die gut mit den aus der Temperaturabhängigkeit der strahlungsinduzierten elektrischen Leitfähigkeit ermittelten Werten übereinstimmt. Es wird daraus gefolgert, daß es sich um Elektronen handelt. Ihre Beweglichkeit wurde bei Zimmertemperatur zu 4·10−7 cm2/Vsec abgeschätzt. Die Polarisationsspannung steigt proportional zur äußeren Spannung bis etwa 400 V äußerer Spannung an, darüber geringer als linear, erreicht bei etwa 1800 V ein Maximum und nimmt mit wachsender äußerer Spannung wieder ab. Dieser Verlauf kann annähernd quantitativ durch bei Abweichung von der Proportionalität einsetzende Injektion und dadurch bewirkten Abbau der Raumladung bei gleichzeitiger Verschiebung des Ladungsschwerpunktes erklärt werden.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Czechoslovak journal of physics 18 (1968), S. 1390-1401 
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper the results of calorimetric measurements of the correlation factor erg/cm2 R for filtered and unfiltered X-radiation in the energy region up to 220 keV are given. The value of the correlation factor for X-radiation filtered by 3 mm Cu measured by a calorimeter is compared with the values of the correlation factor calculated by an independent method from the energy spectra of the same radiation. The initial spectra are obtained by means of a numerical graphical method from transmission curves measured by means of an ionization chamber in copper and tin. This comparison has shown very good agreement between the calorimetric value of the correlation factor 3·-45. 103 erg/cm2 R and those calculated by using White's values of the correlation factor depending on the X-radiation energy, provided the average energy required to produce an ion pair in air is 34·0 eV. The experimental results thus obtained enable us also to evaluate the amount of average effective energy of the measured X-radiation which is equivalent to the energy of monochromatic X-radiation having the same correlation factor, in comparison with the effective energy, currently determined by ionization measurements of the half-value layers.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 244 (2000), S. 45-50 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The long-lived radionuclide 129I (T 1/2 = 15.7 My) occurs in the nature in very low concentrations. Since the middle of our century the environmental levels of 129I have been dramatically changed as a consequence of civil and military use of nuclear fission. Its investigation in environmental materials is of interest for environmental surveillance, retrospective dosimetry and for the use as a natural and man-made fracers of environmental processes. We are comparing two analytical methods which presently are capable of determining 129I in environmental materials, namely radiochemical neutron activation analysis (RNAA) and accelerator mass spectrometry (AMS). Emphasis is laid upon the quality control and detection capabilities for the analysis of 129I in environmental materials. Some applications are discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 245 (2000), S. 447-453 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract appeared in the Journal of Radioanalytical and Nuclear Chemistry, Vol. 243, No. 2 (2000) 467–472. During the electronic submission of the paper the file was damaged, and parts were left out. In order to correct this, we publish the correct paper as a whole. Iodine-129 may be no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioactive contamination. Since 1943, 129I/127I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer, living near a nuclear reprocessing facility have contained 129I which is 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of 129I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that 129I may be helpful to evaluate past radiation hazard from fission products.
    Type of Medium: Electronic Resource
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