The only published determinations of the energy of the ?-radiation emitted when lithium is bombarded by protons with energy less than 400 keV have been made by absorption measurements of secondary electrons in aluminium. Gentner (1937) found that the radiation at 90� from a thick lithium target at 300 keV, had the same half-value thickness as that at 550 keV, corresponding to about 17 MeV. Tangen (1946), however, reported that the radiation emitted at 0� at both 300 and 400 keV had energy 14�5 � 0�5 MeV.

SummaryProton capture reactions in light nuclei provide y-radiation with energy controllable by variation of proton energy. The radiation from proton capture by 7Li has been used to investigate the (y,n) reactions in 160 and 63CU over an energy range of 300 keV around 17·7 MeV. No. resonant behaviour was observed in 16 0. A variation in the 63CU photoneutron cross section is interpreted as the combined effect of many unresolved levels.