Search for spontaneous fission of plutonium and americium nuclides using gamma spectrometry

Spontaneous fission in americium and plutonium isotopes was investigated using high-resolution gamma spectrometry. This process was investigated through analysis of a certified PuO2 sample spectrum obtained from the IAEA database of reference spectra. Measurements were carried out with a HPGe detector, and detection efficiency calibration was performed by Monte Carlo simulations using GEANT4. There are no peaks observed that can be ascribed to beta decay of expected spontaneous-fission daughters. Thus, lower experimental limits on the partial half-lives for some spontaneous fission channels in 238-242Pu and 241Am were established. In many cases these limits have exceeded current theoretical predictions for cold fission done by S.B. Duarte et al., indicating the need to refine current models for the description of this process.