Cross Section for Excitation ofPb207mby Inelastic Scattering of Neutrons

Abstract
The cross section for the excitation of the 0.8-sec metastable state of Pb207 by inelastic neutron scattering has been measured for neutron energies up to 3.1 Mev. Neutrons were produced by the Li(p, n) reaction. The lowest neutron energy for which excitation is observed is 1.6 Mev. This is in agreement with the level scheme for Pb207 based on other information. For the first 800 kev above threshold, the cross section rises approximately linearly, attaining a value of 75 millibarns at 2.4 Mev. After leveling off, it abruptly increases at 2.75 Mev and has a value of 190 millibarns at 3.1 Mev. It is judged that the absolute values of the cross section are accurate to ±40 percent. The absolute cross section for excitation of the metastable state as a function of neutron energy is calculated by the use of the strong interaction theory of nuclear reactions. The theoretical predictions agree well with the measured curve.