TOTAL CROSS SECTIONS OF RARE EARTHS FOR FAST NEUTRONS

The total neutron cross sections averaged over resonances have been measured for Nd, Sm, Er, Yb, and Hf as functions of neutron energy from 0.06 to 3 Mev. The cross-section curves have shapes which change gradually with atomic weight and are in agreement with the values predicted by the theory of Feshbach, Porter, and Weisskopf.