Fragment-correlated γ-ray emission from ²⁵²Cf(sf)

Recent experimental results on the yield of prompt fission γ rays from the spontaneous fission of ²⁵²Cf will be presented. A newly developed twin Frisch-gridded ionization chamber [S. Marin et al., NIM A, 1048, 168027 (2023)] was used to tag fission events and measure the masses and total kinetic energies (TKE) of the fission fragments. In a first experiment, the ionization chamber was combined with a trans-stilbene organic scintillator array to measure the neutrons and γ rays emitted by the fission fragments. The experimental results reveal that the total γ-ray multiplicity saturates at sufficiently high internal fragment excitation energies, and distinct behaviors for the yield of γ rays from light and heavy fragments were observed, suggesting the presence of complex angular momentum generation modes. In a second experiment, the chamber was placed inside a Gammasphere, a world-class γ-ray spectrometer which provides total γ-ray yield and fragment identification. The study of spin sawtooth [J. Wilson et al., Nature 590, 566 (2021)] and its variation with the TKE will be discussed.