Studies of Rare Earth Alpha Emitters

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, Dy¹⁵³ (5 hr) and Dy¹⁵⁴ (13 hr). Mass assignments have been made for two other alpha emitters, Dy¹⁵² (2.3 hr) and Tb¹⁵¹ (19 hr). A new 10-hr electron-capture isotope has been identified as Dy¹⁵⁵. Evidence is also presented for the discovery of another isotope, Dy¹⁴⁹ (8 min), which was produced by a N¹⁴ ion bombardment on praseodymium.