On the Angular Distribution in Nuclear Reactions and Coincidence Measurements

The 4.6-hour Kr" period was reported by SnelP as a result of deuteron bombardment of krypton. The Kr" period was not obtained by Clancy' as a result of alpha-particle bombardment of selenium. In the latter bombardments, only a 114-minute krypton period, assigned to the excited level of stable Kr~, and a 33-hour krypton period, assigned to Kr ' ", were observed. The Kr'~ period was then considered by Clancy to be long or fairly short, and a 4-hour krypton activity obtained from deuteron bombardment of krypton was presumed to be caused by Kr 7. The 4.6-hour Kr" activity has been reported by Seelmann-Eggebert and Born' as a result of uranium fission by decay of the 3-minute Br" ~%'. Seelmann-Eggebert and H. J. Born, Naturwiss. 31, 59 (1943). siotope, and also as a result of Sr(n, n) and Rb(n, P) reactions. ' A 4.4+0.2-hour half-life of p -activity appears in Fig. 2, which shows the decay curves of separated p and p+ krypton activity from alphaparticle bombardment of Hilger selenium. This curve indicates that the Kr" isotope is produced by alpha-particle bombardment of selenium. Figure 4 shows the Se, Br, Kr part of the periodic table. The new Kr~' isotope and new reactions found are noted by heavy lines.