The voltage regulation of the Rice Institute pressure electrostatic generator has been improved by the use of a modulated electron current which proceeds up the vacuum tube in the opposite direction to the positive ions. The auxiliary apparatus is composed of a magnetic voltage analyzer and an electronic potential regulator. Calculations indicate that at 1 Mev the potential is controlled to ±150 volts. The resonances in the production of gamma-rays and soft radiation (pairs) when ${\mathrm{F}}^{19}$ is bombarded by protons have been studied with proton energies of from 800 to 1400 kev. Resonances for the emission of gamma-rays have been observed at 820, 862, 890, 927, 1076, 1107, 1122, 1161, 1274, 1335, and 1363 kev. The experimental half-widths of these resonance levels vary from 1.9 to 50 kev. Resonances for the production of soft radiation (pairs) have been observed at 832, 1100, 1220, and 1362 kev; the widths of these resonance levels vary from 28 to 85 kev. An explanation of the varying intensities and widths of the levels can be made on the basis that the protons which produce the disintegrations and the alpha-particles which result have several different values of angular momentum.

• Received 1 October 1946

DOI:https://doi.org/10.1103/PhysRev.70.882