Alpha-Gamma Angular Correlations in Three Heavy Odd-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>A</mml:mi></mml:math>Nuclides

Abstract

Angular correlations between alpha particles and gamma rays have been measured in liquid sources of three separate nuclides, americium-243, uranium-233, and neptunium-237. The angular-correlation functions were experimentally determined for five transitions, and the relative angular-momentum mixing ratios for these transitions were deduced. The mixing ratios of $L=2 \mathrm{and} 0$ agree with theory, but the $L=4 \mathrm{and} 2$ mixing ratios are somewhat higher than predicted. Upper limits of the half-lives of 99-keV and 45-keV states in ${\mathrm{Th}}^{229}$ were measured, respectively, as 0.8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ and 1.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec. From a comparison of the attenuated angular correlation in ${\mathrm{Am}}^{243}$, and a previously measured angular correlation in ${\mathrm{Am}}^{241}$, it is deduced that an extranuclear interaction occurs whose time duration is less than 1.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec.