146Gd and 144Sm excited by the (p,t) reaction on radioactive targets

The (p,t) reaction has been used to study the closed-shell nuclei 146Gd and 144Sm, the former exhibiting some characteristics of a doubly closed shell. Exotic radioactive targets of 148Gd (t1/2 = 75 yr) and 146Sm (t1/2 = 7×10^7 yr) obtained from chemical and isotope separation of irradiated beam-stop material were employed. The ground-state mass excess of 146Gd was measured as being Δu = -76.083(15) MeV and the first excited state is confirmed as being a 3- state at 1.580-MeV excitation energy. Thirteen states were observed in 146Gd and 23 in 144Sm. The pairing-monopole and pairing-quadrupole states in both nuclei are observed for the first time. These levels are higher than systematics would predict, confirming a proton-subshell closure in 146Gd, and are split in 144Sm, indicating a strong interaction between nuclear modes

Report to the DOE Nuclear Data Committee, 1984

Experimental results are discussed for: /sup 6/ /sup 7/Li(n,/sup 4/He) cross sections at 14 MeV, neutron elastic and inelastic scattering from carbon near 14 MeV, neutron capture cross sections for /sup 46/Ca and /sup 48/Ca at stellar temperatures, revised neutron cross sections for /sup 142/ /sup 143/ /sup 144/Nd, fragment angular distribution for neutron fission of /sup 232/Th, neutron differential scattering measurements in the actinide region, nuclear structure of /sup 244/Am, conversion coefficients of the M4 transition in /sup 193m/Ir, gamma-ray and conversion-electron decay of the /sup 238/U shape isomer, and levels of /sup 244/Cm populated by the beta decay of 10-hr /sup 244g/Am and 26-minute /sup 244m/Am. Calculations described include tests of microscopic optical models for neutron and proton scattering on light nuclei in the range 14 to 45 MeV, a new dynamic model for fission, and the necessity of discrete-level modeling in isomer ratio calculations for neutron-induced reactions on deformed nuclei. Also, a reevaluation for ENDL of sigma(n,f) and anti nu p for /sup 235/U and /sup 239/Pu from 100 keV to 20 MeV is described. 31 references. (WHK