Abstract
The beta- and gamma-ray spectra of 55-minute were studied by means of magnetic and scintillation spectrometers. A first forbidden unique (, yes) beta transition takes place to the ground state of in 7±2% of all decays with an end-point energy of 3.45±0.02 Mev and a value of 7.8 (). Beta transitions to the second excited level of at 1.52 Mev take place in 85±6% of the transitions and have an end-point energy of 1.91±0.02 Mev (). The remaining 8±4% of the beta transitions take place to the first excited level at 1.266 Mev (). Three gamma rays were found with energies of 0.246±0.003, 1.266±0.010, and 1.520±0.010 Mev, and relative intensities of 0.9±0.1, 1, and 0.85±0.05, respectively. The 0.240- and 1.266-Mev gamma rays are in cascade. Each of the three gamma rays is in coincidence with beta rays with end-point energies of 1.90±0.05 Mev. A beta-gamma delay is observed with a half-life of (0.95±0.05)× second. The metastable level is shown to be the second excited state. A decay scheme based on these data is proposed.
- Received 30 July 1956
DOI:https://doi.org/10.1103/PhysRev.104.740
©1956 American Physical Society