A high-resolution multi-parametric study of 239Pu(nth, f) with the Cosi-Fan-Tutte spectrometer

Abstract The Cosi-Fan-Tutte spectrometer has been used to measure for the first time in one go the mass-nuclear charge-energy correlations of well-resolved light group masses for 239 Pu(n th , f). About 2 × 10 6 events were collected and analysed. The global mass distribution is consistent with the Lohengrin data. The mean proton odd-even effects in yields and energy are δ p =(11.8±0.3)% and δE K o −e=0.49±0.15 MeV respectively. The δ p ( E L ) varies from ≈7% to ≈25% for E L =90 to 116 MeV. The present analysis consists of 21 values of E L compared to only 5 values for Lohengrin. The apparent mean neutron odd-even effect δ n =(3.5±0.1)% is much lower than the δ n = (6.5±0.7)% for Lohengrin. The mean value of conditional variance 〈 σ z 2 ( Z | A )〉=(0.42±0.02); the 〈 σ z 2 ( Z | A )〉 increases from 230 Th to 250 Cf and this behaviour turns out to be important for understanding the dynamics of the fission process.