An attempt has been made to produce the 110-msec energetic electron activity recently reported to result from photon irradiation of lithium. The activity has not been found in the high-energy proton bombardment of lithium, and the production cross section is <5×${10}^{-4\mathrm{}}$ times that for producing ${\mathrm{Li}}^9$ from boron under the same conditions. This indicates that the high-energy proton activation cross section of lithium for such an an activity is ≤1 μb.

• Received 23 August 1963

DOI:https://doi.org/10.1103/PhysRev.133.B1