William Michael Schmitt

Possible observation of the 12+[880] orbital in 96249Cm

Abstract The position of the K 17 2 shell orbital plays a significant role in determining the shell correction energy and hence the stability of the superheavy elements. A deformed component of this orbital, 1 2 + [880] , comes down in energy with increasing prolate deformation, and is expected to have an excitation energy of less than 2 MeV in nuclei with N = 153. We have performed the reaction 248Cm(4He,3He) using 98.5-MeV alpha particles from the IUCF cyclotron to populate high-l states in 249Cm. this reaction preferentially excites high-l states because of the angular momentum mismatch. The emerging 3He ions were momentum analyzed with the K600 magnetic spectrometer. Spectra were measured at θcm = 4.1°, 6.1°, 10.2°, 12.2°, and 16.2° The spectrometer was calibrated with the 208Pb(4He,3He) and 232Th(4He,3He) reactions at the same incident energy. Three strong peaks were identified in the 248Cm(4He,3He) spectrum and these have been given tentative assignments: 593 keV, 15 2 11 2 − [725] ; 1560 keV and 1898 keV, 17 2 1 2 + [880] , 15 2 13 2 − [716] . Our data do not distinguish between the 17 2 + and 15 2 − assignments.

Study of the high-j states in 249Cm

We have performed the reaction 248Cm(4He, 3He) using 98.5-MeV alpha particles from the IUCF cyclotron to populate high-j states in 249Cm. A tentative assignment of the k17/2 component of the 1/2+[880] Nilsson state has been made.