The disintegration of lutecium of mass 177.

The beta and gamma spectra of 6.9 day lutecium have been measured using a thin lens spectrometer. Gamma rays of average energies 112.2 ± 0.6 kev., 206.3 ±1.0 kev., and 317-3 ± 1.5 kev., have been found, the former two of comparable intensity and the latter much weaker. Characteristic X-radiation from Hf has also been observed. These energies are computed from four conversion lines on the beta spectrum at 46.9± 0.5 kev., 101.8±0.6 kev., 109.9 ±0.6 kev., and 141.4 ±0.8 kev., as well as from photoelectron lines using lead, gold, and tin radiators. Beta end points based on a Kurie plot occur at l69±10 kev., 366 ± 25 kev., and 495± 5 kev. A decay scheme is proposed consistent with these results. The great importance of avoiding source charging has been demonstrated by shifts of the conversion lines up to 20 kev. when a source mounting of thin nylon was used. Decay has been followed for 400 hours and the half period found to be 6.98 ± 0.10 days.