Neutron Capture Gamma-Ray Spectra of the Nickel Isotopes

The spectra of gamma radiation following pile-neutron capture in separated isotopes of nickel have been measured with a three-crystal scintillation pair spectrometer as well as with a single-crystal scintillation counter. Energies and intensities of the gamma rays from each isotope are reported. Each of the lines observed with natural nickel has been assigned to ${\mathrm{Ni}}^{58}(n, \gamma ){\mathrm{Ni}}^{59}$, ${\mathrm{Ni}}^{60}(n, \gamma ){\mathrm{Ni}}^{61}$, or ${\mathrm{Ni}}^{62}(n, \gamma ){\mathrm{Ni}}^{63}$. In some cases, gamma rays of nearly identical energies are found in two, or in all three, isotopes. Additional gamma rays not resolved in the natural nickel spectrum appear in ${\mathrm{Ni}}^{58}(n, \gamma ){\mathrm{Ni}}^{59}$ at 7.65 Mev, and in ${\mathrm{Ni}}^{60}(n, \gamma ){\mathrm{Ni}}^{61}$ at 7.65 Mev, and in ${\mathrm{Ni}}^{60}(n, \gamma ){\mathrm{Ni}}^{61}$ at 4.70 and 5.55 Mev. The spectrum of ${\mathrm{Ni}}^{62}(n, \gamma ){\mathrm{Ni}}^{63}$ is dominated by a strong line at 6.80 Mev, presumably the ground-state transition.