The total photoneutron production cross sections for ${\mathrm{Li}}^6$ and ${\mathrm{Li}}^7$ were determined from the yields measured with a neutron detector. The efficiency of the neutron detector was found from the comparison of the detected and computed neutron yield from copper. In the calculation of the cross section the inverse photon matrix formulation of the photon difference method was used. The ${\mathrm{Li}}^6$ cross section has a peak at about 12.5 Mev and its absolute value at the peak is equal to 2.8±0.53 mb. The ${\mathrm{Li}}^7$ cross section has a peak at about 14 Mev and its value at the peak is equal to 3±0.75 mb.

• Received 24 April 1958

DOI:https://doi.org/10.1103/PhysRev.113.886