THE DECAY OF Pm151

Abstract

The radiations from Pm¹⁵¹ have been studied by external and internal conversion measurements and electron–electron, electron–beta, electron–gamma, and beta–gamma coincidence experiments. Thirty-six transitions have been identified. A decay scheme incorporating 30 of these has been established by energy and coincidence measurements with levels in Sm¹⁵¹ at 0, 0.0048, 0.0658, 0.0697, 0.0915, 0.1048, 0.1677, 0.1684, 0.2090, 0.3239, 0.3449, 0.4445, 0.741, and 0.821 Mev. The half-life of the 0.0048-Mev level is (19 ± 10) × 10⁻⁹ sec. The total decay energy is 1.195 ± 0.010 Mev.