RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
Volume 27 , Issue 1
Showing 1-16 articles out of 16 articles from the selected issue
  • Makoto YOSHIDA, Hiroshi MIYAHARA, Tamaki WATANABE
    1978 Volume 27 Issue 1 Pages 1-6
    Published: January 15, 1978
    Released: September 07, 2010
    JOURNALS FREE ACCESS
    The self-absorption of a thin source for 4πβ-counting was studied through measuring β-ray counting efficiencies against spherical and slab sources by means of 4πβ-γ coincidence counting method. The former was the granular source which consisted of fine ion exchange resin particles adsorbing a radioactive nuclide, and the latter was the membraneous source in which a radioactive nuclide was sandwiched with two absorbers of VYNS.
    On the basis of the measuredβ-ray counting efficiencies, it was tried to estimate systematically the self-absorption of fine spherical and thin slab sources with homogeneously dispersed radioactive nuclide. The measured self-absorption of both sources, however, was not well explained by the conventional calculation owing to the exponential absorption of β-rays with only a mass absorption coefficient. The disagreement seemed to originate mainly from the thinness of the membraneous sources and the use of4πβproportional counter which can detect low energyβ-rays of several hundred eV. Therefore, using the approximate formula improved according to the assumptions that the absorption of β-rays can be expressed with two mass absorption coefficients and that the β-ray path length in the slab source has an upper limit, relatively good agreement was obtained.
    The relation between the position of a radioactive nuclide in the slab source and the counting efficiency of the β-rays emitted there, also, indicated the existence of low energy β-rays which was due to the scattering of β-rays in a source itself.
    As the result, it turned out that the self-absorption could markedly be reduced when a radioactive nuclide was distributed on the surface of source grain.
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  • Takahiko AOYAMA, Tamaki WATANABE
    1978 Volume 27 Issue 1 Pages 7-13
    Published: January 15, 1978
    Released: September 07, 2010
    JOURNALS FREE ACCESS
    This paper describes the performance of a hybrid spark chamber for measuring β-ray emitting radionuclide distribution on a plane source, which was developed to improve the instability of usual self-triggering spark chambers. The chamber consists of a parallel plate spark chamber gap and a parallel plate proportional chamber gap composed of mesh electrodes in the same gas space, and is operated by flowing gas, a mixture of argon and ethanol saturated vapor at 0°C, continuously through it.
    Instability is due to the occurrence of spurious sparks not caused by incident particles and it became conspicuous in the small intensity of incident particles. The hybrid spark chamber enabled us to obtain good counting plateau, that is, good stability for especially small intensity of β-rays and even for the background by setting up gas multiplication in the proportional chamber gap moderately high.
    Good spatial resolution less than 1 mm was obtained for3H and14C by keeping the distance between the chamber cathode and the source less than 1 mm. In order to obtain good spatial resolution, it is desirable to keep the overvoltage as small as possible while small overvoltage results in the deterioration of the uniformity of sensitivity. It was found by theoretical estimation and experiment that for a given large overvoltage the spatial resolution was improved by increasing the gas multiplication in the proportional chamber gap.
    The hybrid spark chamber has a relatively long dead time. When there being a number of active spots having different activities in a detection area, the sparking efficiency of a weak active spot also decreases by large counting loss due to the total strong activity. Since the ratio between sparking rates of each spot, however, is equal to the ratio of their activities, it was confirmed that the spark image of weak active spots was also obtained easily with relatively long exposure time.
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  • Gensei ITAYA, Kazuhiko KOJIMA
    1978 Volume 27 Issue 1 Pages 14-19
    Published: January 15, 1978
    Released: September 07, 2010
    JOURNALS FREE ACCESS
    A coarse Fresnel zone plate (FZP) may be used as a large-area coded aperture for imaging incoherent sources. The longitudinal and lateral spatial resolutions are discussed on the basis of experiment using an FZP having 18 or 19 zones as an aperture. In this paper, it is then shown that the lateral spatial resolution is about 5 mm and the longitudinal is about 1 cm, respectively and it is appropriate to use the longitudinal resolution factor 3.7 as a guide to know the tomographic effect.
    These results may be extended for imaging incoherent gamma-ray sources. According to our experiments, radioactivity of several tens of a millicurie is necessary for imaging with99mTc, when using X-ray film as a detector. Therefore, it is important to improve the detector in order to apply to the human organ imaging generally.
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  • Teruko SAWAI, Toshinari SHIMOKAWA, Yasushi MIKI, Koichi OSEKO, Takeshi ...
    1978 Volume 27 Issue 1 Pages 20-26
    Published: January 15, 1978
    Released: September 07, 2010
    JOURNALS FREE ACCESS
    Present work deals with the effects of gamma irradiation from60Co γ-ray source upon aqueous solutions of three kinds of surfactants. When dilute aqueous solutions of sodium dodecyl sulfate (SDS, anionic), cethyl trimethyl ammonium chloride (CTAC, cationic), and polyoxyethylene lauryl ether (POE, non-ionic) were irradiated with γ-rays at a room tempe-rature, the residual concentration, products, surface tension, and forming power were examined by colorimetric method, IR spectrophotometric method, gaschromatography, Ross-Miles method, and Traube's stalagmometer etc.. These surfactants were decomposed by the irradiation and thus the surface tension increased and the forming power, on the contrary, decreased with dose. Radiation chemical yields (G-value) of the degradation were about 1 for the solutions of SDS and CTAC, and about 0.3 for the POE solution. From the experimental results, it was found that following chemical reactions seem to occur followed by the radialysis of water;
    a) bond cleavage of ester for SDS, of CN for CTAC, and of oxyethylene for POE,
    b) hydrogen abstraction from the surfactants,
    c) production of CO bond in the presence of dissolved oxygen.
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  • Yasuyuki MAKI, Toshiaki NOJIRI
    1978 Volume 27 Issue 1 Pages 27-29
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Akira YOSHITAKE, Takeshi KAMADA, Masaaki HAZUE
    1978 Volume 27 Issue 1 Pages 30-32
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Toshiaki SHIMIZU, Jun-ichi FUKAMI
    1978 Volume 27 Issue 1 Pages 33-34
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Hyobu ICHINOHE, Hirokuni SUGIMOTO, Tadayoshi ISHIKAWA
    1978 Volume 27 Issue 1 Pages 35-38
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Katsuya NAGASE, Kenshiyo MABUCHI, Yoshinari ARAKAWA, Masayoshi TANAKA, ...
    1978 Volume 27 Issue 1 Pages 39-42
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Keisuke KANAO, Shizumori ISHIHARA, Yumiko ISHIHARA, Etsuko YAGI, Masah ...
    1978 Volume 27 Issue 1 Pages 43-45
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Keisuke KANAO, Shizumori ISHIHARA, Minoru HONDA, Tadashi OGAWA, Etsuko ...
    1978 Volume 27 Issue 1 Pages 46-49
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Nobuko SUZUKI, Hironori OBAYASHI, Gentetsu SATONAKA, Kyoichi FUJII
    1978 Volume 27 Issue 1 Pages 50-52
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Akio KOMATANI, Kohichi YAMAGUCHI, Makoto TAKAMIYA, Jiro WATARAI, Hisas ...
    1978 Volume 27 Issue 1 Pages 53-54
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Ryo FUNAKI, Hirobumi ISHIDA, Shigetoshi SHIRAKAWA, Wataru KUTANI, Kazu ...
    1978 Volume 27 Issue 1 Pages 55-58
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Shigeo BABA, Tsuyoshi GOROMARU
    1978 Volume 27 Issue 1 Pages 59-68
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • 1978 Volume 27 Issue 1 Pages A1787-A1684
    Published: January 15, 1978
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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