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The level density and γ-ray strength function (γSF) of 243 Pu have been measured in the quasi-continuum using the Oslo method. Excited states in 243 Pu were populated using the 242 Pu(d, p) reaction. The level density closely follows the constant-temperature level density formula for excitation energies above the pairing gap. The γSF displays a double-humped resonance at low energy as also seen in previous investigations of actinide isotopes. The structure is interpreted as the scissors resonance and has a centroid of ω SR = 2.42(5) MeV and a total strength of B SR = 10.1(15) µ 2 N , which is in excellent agreement with sum-rule estimates. The measured level density and γSF were used to calculate the 242 Pu(n, γ) cross section in a neutron energy range for which there were previously no measured data.

Nuclear model calculations of discrete γ -ray production cross sections produced in 48 Ti(n, n γ i ) 48 Ti and 48 Ti(n, 2nγ i ) 47 Ti reactions were made as a function of incident neutron energy from E n = 1 MeV to 35 MeV and compared with new experimental results using the large-scale Compton-suppressed germanium array for neutron induced excitations (GEANIE) at LANSCE. The Hauser-Feshbach reaction code GNASH, incorporating the spin distribution for the preequilibrium process calculated with the FeshbachKerman-Koonin (FKK) quantum-mechanical preequilibrium theory, was used to calculate partial γ -ray transition cross sections. The comparisons of calculated and experimental data demonstrate that, the FKK model for preequilibrium leads a better overall reproduction of the experimental data above E n = 10 MeV, where preequilibrium processes are important. The FKK calculation predicts a strong reduction in the high-spin state population in 48 Ti by inelastic scattering. Population of low-spin states was also affected, however the change in the low-lying 983.5-keV (2 + ) state production is small because almost all γ -ray decay cascades feed this transition. In addition, the FKK calculation has a significant impact on the partial γ -ray transition cross sections for the (n, 2n) reaction above E n = 15 MeV. The calculated cross sections for high-spin states in 47 Ti are reduced, and those from the low-spin states are enhanced, in agreement with the experimental cross section data.