Abstract
Half-life,P L /P K -capture ratio andβ-spectrum of Tl204 were studied with a scintillation spectrometer. To avoid source absorption and scattering troubles, the Tl204 source was built in in the lattice of NaJ(Tl)-crystals. The half-life measurements were performed over a period of 2,2 years, and we obtained a half-life of 3.81±0.04 years. TheP L /P K -capture ratio was determined at 0.41±0.03. This ratio gives a desintegration energy of 442 +30−24 keV for the unique first forbidden electron capture decay of Tl204. For the branching ratio of electron capture toβ −-decay we found a value of (2.15±0.06)% and for the ratio ofK-capture toβ −-decay a value of (1.53±0.05)%. Theβ −-spectrum of Tl204 was measured from 200 down to 6 keV and yields an experimental shape factor which deviates below an energy of ∼90 keV from the theoretical shape factorq 2 L 0+9L 1. Reasons for this deviation which is opposite to the one obtained with magnetic spectrometers are discussed.
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Herrn Professor Dr. O.Haxel möchten wir für anregende Diskussionen herzlich danken. Einen Teil der Intensitätsmessungen zur Bestimmung der Halbwertszeit hat Herr Dipl.-Phys. K.Egelkraut ausgeführt, der uns auch in dankenswerter Weise bei der Züchtung der Kristalle unterstützt hat. Das Bundesministerium für Atomkernenergie hat diese Arbeit durch Bereitstellung apparativer Mittel gefördert.
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Leutz, H., Ziegler, K. Halbwertszeit, Elektroneneinfangverhältnis und β-Spektrum des Tl204 . Z. Physik 166, 582–589 (1962). https://doi.org/10.1007/BF01378115
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DOI: https://doi.org/10.1007/BF01378115