γ-rays >120 keV emitted in the decay of 23.5-min 239U

The β decay of 239U populates at least 31 levels in 239Np below 1100 keV, but the feeding of levels above 118 keV is weak (about 1%, total) and poorly characterized. We have prepared sources by neutron capture in 238U followed by chemical purification. Spectra were obtained with Ge detectors, sometimes with absorbers. For energies above 120 keV, these spectra confirmed 94 and rejected 23 previously reported transitions, and revealed 43 new transitions.