Low-energy $\gamma$ rays, in the range from 45 to 230 keV, following the spontaneous fission of ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$, are observed with a high-resolution Ge(Li) detector [full width at half maximum (FWHM) 500 eV at 81 keV], in coincidence with $K$ x rays from the fission fragments, observed with a Si(Li) detector (FWHM 350 eV at 31 keV). Sixteen 1024-channel $\gamma$-ray spectra were accumulated and sorted by computer, corresponding to windows set on $K$ x rays from Y, Zr, Nb, Mo, Tc Ru, Rh, Pd, Pr, Ce, La, Ba, Cs, Xe, I, and Sb. In conjunction with previous works, these data allowed both mass and charge assignments to be made for a number of the observed $\gamma$-ray transitions.

• Received 2 June 1971

DOI:https://doi.org/10.1103/PhysRevC.4.1927