Disintegration Schemes of Radioactive Substances IX.Mn52andV48

Abstract

The radiations emitted in the decay of $_{25}\mathrm{Mn}^{52}$ (6.5 day) and of $_{23}\mathrm{V}^{48}$ have been investigated by spectrometer and coincidence methods. ${\mathrm{Mn}}^{52}$ decays with the emission of positrons of maximum energy 0.582\ifmmode\pm\else\textpm\fi{}0.015 Mev, followed by three gamma-rays in cascade, of energies 0.734\ifmmode\pm\else\textpm\fi{}0.015 Mev, 0.940\ifmmode\pm\else\textpm\fi{}0.02 Mev, and 1.46\ifmmode\pm\else\textpm\fi{}0.03 Mev, respectively. These energies are the multiples 3, 4, and 6 of 0.240 Mev, within the experimental errors. The orbital electron capture by ${\mathrm{Mn}}^{52}$ leads to the same excited state of ${\mathrm{Cr}}^{52}$ as the positron emission with which it competes. The positrons of ${\mathrm{V}}^{48}$ are emitted with a maximum energy of 0.716\ifmmode\pm\else\textpm\fi{}0.015 Mev, with successive emission of two gamma-rays of 1.33\ifmmode\pm\else\textpm\fi{}0.03 Mev and 0.980\ifmmode\pm\else\textpm\fi{}0.02 Mev energy. These gamma-ray energies are in the ratio 4:3. From the disintegration schemes one finds the mass differences between neutral atoms: ${\mathrm{Mn}}^{52}$-${\mathrm{Cr}}^{52}$ = 5.10\ifmmode\pm\else\textpm\fi{}0.15\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ a.m.u. and ${\mathrm{V}}^{48}$-${\mathrm{Ti}}^{48}$ = 4.37\ifmmode\pm\else\textpm\fi{}0.12\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ a.m.u. Some evidence is also presented concerning the disintegration of ${\mathrm{V}}^{52}$ and of ${\mathrm{Sc}}^{48}$. The energy levels of ${\mathrm{Cr}}^{52}$ and ${\mathrm{Ti}}^{48}$ identified in the radioactive processes are compared with those found by other methods. The disintegration energies of several nuclei studied are examined with a view to their dependence on atomic weight. It is shown that beta-ray theory explains consistently the lifetimes, the shapes of the positron spectra, and the ratio of electron capture to positron emission if one assumes tensor interaction, angular momentum change $\ensuremath{\Delta}I=0$ or $\ensuremath{\Delta}I=\ifmmode\pm\else\textpm\fi{}1$ (not 0\ensuremath{\rightarrow}0) without parity change in the case of ${\mathrm{Mn}}^{52}$ and with parity change in the case of ${\mathrm{V}}^{48}$.