A New Measurement of the Packing Fractions of the Nickel Isotopes

The packing fractions of the nickel isotopes have been measured by comparison with known hydrocarbon lines using a double-focusing mass spectrograph. A new constant source of positive ions was used which produces mass spectra as high as the eighth order. The values of the packing fractions were determined to be: ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$(-8.29×${10}^{-4\mathrm{}}$); ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$(-8.69×${10}^{-4\mathrm{}}$); ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$(-8.75×${10}^{-4\mathrm{}}$); ${}_{}{}^{62}{}_{}{}^{}\mathrm{Ni}$(-9.01×${10}^{-4\mathrm{}}$); ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$(-8.62×${10}^{-4\mathrm{}}$). The binding energies of the neutrons added to form the heavier isotopes are tabulated. An explanation is suggested for the differences in the packing fractions reported here and those given by Okuda and his associates.