Abstract
The nuclear level scheme of has been studied utilizing a variety of experimental methods. From the reaction , low-energy -ray transitions were measured between 40 and ≈1350 keV with a bent-crystal spectrometer, and the () conversion-electron spectrum was investigated in the energy range between 160 and 1300 keV with a double-focusing spectrometer. Altogether, some 160 transitions were found, and multipolarities were assigned for about 50 of these. High-energy rays from neutron capture in were measured in the energy region between 4.9 and 8.2 MeV with a Ge(Li) detector operated in the pair mode; 49 transitions were found. Furthermore, the reactions , , , and have been studied at 12-MeV beam energy, using a broad-range magnetic spectrograph. Combining the results of all these experiments, a level scheme containing 90% of the intensity of the low-energy () spectrum of was constructed consisting of the following levels: the ground-state rotational band up to the level; the (-vibrational) band at 888.22 keV including all members up to the possible state; the octupole-vibrational or [411↑-523↑] band with the band head at 1148.29 keV and including members up to the tentative and levels; the [521↑+523↓] band at 1535.89 keV containing members up to the and possibly the level; a band (probably octupole) with and members at 1275.4 and 1357.0 keV, and possibly the member at 1520 keV; a tentative band with and members at 1206.1 and 1390.3 keV, suggesting the level at 1127 keV; the [521↑-523↓] band at 1745 keV containing states up to the level; the [642↑+521↓] band at 1770 keV containing levels up to the member; and finally the [642↑-521↓] band at 1866 keV containing levels up to the state. Other unassigned levels were found above 1.4 MeV in the (), (), and high-energy () measurements. The agreement between experimental and calculated cross sections for the () and () reactions was found to be good for the [521↑±523↓] and the [642↑±521↓] states, but not so good for the [642↑±523↓] states. The neutron binding energy in was determined as 8192.8±3 keV.
- Received 16 February 1967
DOI:https://doi.org/10.1103/PhysRev.160.1011
©1967 American Physical Society