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Properties of neutron-rich nuclei in the A˜160 region are important for achieving a better understanding of the nuclear structure in this region where little is known owing to diffculties in the production of these nuclei at the present nuclear physics facilities. These properties are essential ingredients in the interpretation of the rareearth peak at A˜160 in the r process abundance distribution, since theoretical models are sensitive to nuclear structure input. Predicated on these ideas, we have initiated a new experimental program at Argonne National Laboratory. During the first experiment, beams from the Californium Rare Isotope Breeder Upgrade radioactive beam facility were used in conjunction with the SATURN decay station and the X-array. We focused initially on several odd-odd nuclei, where β decays of both the ground state and an excited isomer were investigated. Because of the spin difference, a variety of structures in the daughter nuclei were selectively populated and characterized based on their decay properties. Mass measurements using the Canadian Penning Trap aimed at establishing the excitation energy of the β-decaying isomers were also carried out. Evidence was found for a change in the single-particle structure, which in turn results in the formation of a sizable N=98 sub-shell gap at large deformation. Results from the first experimental campaign using the newly-commissioned β-decay station at Gammasphere are also presented.

ABSTRACT The novae V4742 and V4743 Sagittarii (Sgr) erupted less than a week apart in 2002 September. This paper collects together early IAU Circular observations, plots light curves, and presents our own spectra of these novae. The spectra were collected with equipment commercially available to amateur astronomers. We identify the major spectral emission lines, measuring full widths at half-maximum, velocity widths and equivalent widths. Both novae displayed fast Duerbeck type A light curves. The eruption of V4743 Sgr fits into the spectral classification scheme for novae proposed by Williams et al. with a principal Fe ii spectrum giving way to an auroral spectrum. We observed only the principal Fe ii phase in V4742 Sgr, during which its He i 706.5-nm emission line appeared early then faded along with the Fe ii complex. This was unlike the spectral evolution of V4743 Sgr, in which the He i 706.5-nm line emerged after the Fe ii complex diminished. [ABSTRACT FROM AUTHOR]