. Adventures in radioisotope research;. Radioactive tracers; Radiobiology. THE ACTION OF NEUTRONS ON THE HARE EARTH ELEMENTS 49. 10 days Fig. 1 10 days ^ a) Decay Curve of a Pure and an Impure Yttrium Preparation, b) Samarium Decay Curves (the two days' period only; the weak period of 40 min is not visible;. cally and their separation is attended with very great difficulties. Figure 1 shows the decay of a pure preparation and of one containing some dysprosium. Since yttrium has only one stable isotope, ^^Y, the artificial radio- activity obtained from it is presumably due to the formation |^Y.
. Adventures in radioisotope research;. Radioactive tracers; Radiobiology. THE ACTION OF NEUTRONS ON THE HARE EARTH ELEMENTS 49. 10 days Fig. 1 10 days ^ a) Decay Curve of a Pure and an Impure Yttrium Preparation, b) Samarium Decay Curves (the two days' period only; the weak period of 40 min is not visible;. cally and their separation is attended with very great difficulties. Figure 1 shows the decay of a pure preparation and of one containing some dysprosium. Since yttrium has only one stable isotope, ^^Y, the artificial radio- activity obtained from it is presumably due to the formation |^Y. We find the intensity of the yttrium activity to be times as large as that of dysprosium, both preparations having been activated until saturation was obtained in a paraffin block of 30x30x25 cm edge ; the neutron source was placed on the top of the preparation which w^as covered by a thin shield of paper. The ^-rays emitted by yttrium are absorbed 1() half of their initial value bv mm Al. Lanthanum Marsh and Sugden (4) find days as the half-life of lanthanum and for the intensity of the /?-rays emitted, a value amounting to 35% of that observed for the activity of praseodymium. As we find a value of 22 for the ratio of the radiation intensities of dysprosium and praseody- mium, the lanthanum activity works oul at of that of dysprosium. 4 Tlcvcsy. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hevesy, Georg von, 1885-1966. New York, Pergamon Press
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