NEUTRON-DEFICIENT MEMBERS OF A=139 DECAY CHAIN .2. 4.5-H PR-139

The γ rays emitted following the decay of 4.5-h Pr139 have been investigated with Ge(Li) and NaI(Tl) detectors in singles and anticoincidence configurations. Twelve transitions having the following energies (and relative intensities) were observed: 254.7 (53), 1320.0 (13), 1347.4 (100), 1375.7 (33), 1563.6 (9), 1596.6 (10), 1630.6 (70), 1653.3 (8), 1730.2 (1.6), 1818.4 (7.0), 1907.9 (3.5), and 2015.9 keV (3.0). Using energy sums and the anticoincidence results, we placed states in Ce139 at 0(32+), 254.7 (1/2+), 1320.0(32,52,72), 1347.4(72+), 1596.6(32,52,72), 1630.6(32,52+), 1818.4(32,52+), 1907(32,52+), 1984.9(32,52+), and 2015.9keV(32,52,72+). The assignments were made on the basis of logft values and relative photon intensities. The single particle versus collective behavior of the states is also discussed. © 1969 The American Physical Society.