The spectra of the gamma-radiation emitted by lithium and fluorine under proton bombardment have been investigated with a spectrometer which measures the total energy of electron pairs produced in a thin radiator exposed to the gamma-radiation. A long-suspected 14.8-Mev gamma-ray line from the 440-kev resonance in lithium has been clearly resolved from the well-known sharp line at 17.6 Mev. The gamma-radiation from fluorine has been found to consist of two lines at 6.13±0.06 and 6.98±0.07 Mev, rather than a single line as previously believed. Possible variations in the positions and in the relative intensities of the two lines of each spectrum, with changes in the proton energy, have been investigated by using protons of energies approximately 0.45, 0.7, and 1.15 Mev from the Cornell cyclotron. The gamma-ray spectrometer used in these measurements is described, and a discussion given of the factors limiting its resolution. The resolution is such that the observed width at half-maximum of a sharp gamma-ray line is approximately 5.5 percent of its energy.

• Received 16 April 1948

DOI:https://doi.org/10.1103/PhysRev.74.315