PROMPT GAMMA-RAYS FROM NEUTRON INTERACTION IN 235U AND RESONANCE SPIN ASSIGNMENTS

Prompt γ-ray spectra from individual resonances in 235U+n have been measured using a Ge(Li) detector and the CBNM linear accelerator as a pulsed neutron source. Whereas the spectra show very little structure at high γ-ray energies, several distinct lines have been observed in the range 250 keV < Eγ < 1.5 MeV. By comparison of the spectra from resonances with strongly different capture-to-fission ratios decision is possible between γ-rays associated with capture or fission. Resonance spin assignments are made on the basis of the relative strength of the 642 keV γ-ray de-exciting the 2- level at 687 keV in 236U. © 1969.