Studies of Rare Earth Alpha Emitters

Abstract

A series of bombardments using alpha particles from the Berkeley 60-inch cyclotron on rare earth oxides has resulted in the discovery and mass assignment of two new alpha-emitting isotopes, ${\mathrm{Dy}}^{153}$ (5 hr) and ${\mathrm{Dy}}^{154}$ (13 hr). Mass assignments have been made for two other alpha emitters, ${\mathrm{Dy}}^{152}$ (2.3 hr) and ${\mathrm{Tb}}^{151}$ (19 hr). A new 10-hr electron-capture isotope has been identified as ${\mathrm{Dy}}^{155}$. Evidence is also presented for the discovery of another isotope, ${\mathrm{Dy}}^{149}$ (8 min), which was produced by a ${\mathrm{N}}^{14}$ ion bombardment on praseodymium.