NUCLEAR LEVELS IN 142PR

A combination of (d,p)-reaction spectroscopy and high- and low-energy γ rays following thermal-neutron capture in Pr141 has been used to study the levels in Pr142. The (d,p) reaction populates 65 states below 2 MeV, whereas 37 states below 2 MeV are populated by high-energy γ transitions from thermal-neutron capture. The ground-state Q value determined in the (d,p) reaction is 3622±3 keV, in agreement with the neutron binding energy of 5843.4±1.5 keV. Differential cross sections were measured at nine angles for the (d,p) reaction and interpreted in terms of the distorted-wave Born-approximation reaction theory. Utilizing, in addition, some of the low-energy γ rays observed with a bent-crystal spectrograph and with a Ge(Li) spectrometer, it has been possible to make the following assignments (energy in keV, spin and parity in parentheses): ground state, (2-); 3.683, (5-); 17.740, (3-); 63.746, (6-); 72.294, (4-); 84.998, (1-); 128.251, (5-); 144.587, (4-); 176.863, (3-); and 200.525, (2-). These states are interpreted in terms of configuration mixing between the two configurations πd521νf721 and πg72-1νf721. Not only the energies of the levels but also the transition probability ratios are consistent with this interpretation. The calculated half-life of the 3.683 keV, 5- isomeric state is in reasonable agreement with the experimental value. Tentative spin and parity assignments have been made to levels above 250 keV. © 1968 The American Physical Society.