Decays ofTa182andTa183

Abstract

The ${\ensuremath{\beta}}^{\ensuremath{-}}$ decays of ${\mathrm{Ta}}^{182}$ and ${\mathrm{Ta}}^{183}$ into excited states of ${\mathrm{W}}^{182}$ and ${\mathrm{W}}^{183}$ have been studied using a curved crystal gamma-ray diffraction spectrometer and a homogeneous field, ring focusing beta-ray spectrometer. In each case de-excitation of the daughter nucleus gives rise to complex gamma-ray and conversion electron spectra. Energies and relative intensities of gamma rays and conversion lines arising from 27 transitions in ${\mathrm{W}}^{182}$ and 29 transitions in ${\mathrm{W}}^{183}$ are presented. Internal conversion coefficients and multipolarities have been deduced for most of the transitions and together with the gamma-ray energies form the basis of decay schemes proposed for both ${\mathrm{W}}^{182}$ and ${\mathrm{W}}^{183}$. The two decays are reported together because of the close experimental relationship which existed between them as a consequence of the method used for their production, namely, simultaneous production of ${\mathrm{Ta}}^{182}$ by single neutron capture and ${\mathrm{Ta}}^{183}$ by double neutron capture from stable ${\mathrm{Ta}}^{181}$. A corollary result is the value 1.3\ifmmode\times\else\texttimes\fi{}${10}^{4}$ barns for the thermal neutron cross section of ${\mathrm{Ta}}^{182}$.An interpretation of these results on ${\mathrm{W}}^{182}$ in terms of collective rotational motion has been given by A. Bohr and collaborators [Kgl. Danske Videnscab. Selskab, Mat.-fys. Medd. 29, No. 9 (1955)].