Energy levels in Pb 205 from the decay of Bi 205

Abstract

The energies, spins and parities of 9 excited states in Pb 205 and the probable energies of 8 additional states have been established by studies of 14.5-day Bi 205 decay. The experiments include precision energy measurements on conversion lines in permanent magnet and double focusing spectrometers; measurements of coincidences between pairs of conversion lines in a double long lens spectrometer, and coincidences between high energy gamma rays and low energy conversion lines in the same spectrometer adapted for the purpose; measurements of relative gamma intensities in a scintillation spectrometer. Positons were discovered with a maximum energy of 925 keV, establishing the total decay energy of Bi 205 as 2.65 MeV. The proposed decay scheme contains 28 of the observed transitions and is discussed in the light of the shell model.