The details of a phase-shift calculation of high-energy electron scattering by nuclei are given, together with some preliminary results. A new method for summing the Legendre series for the Coulomb scattering amplitude is described. The results indicate that the erst Born approximation does not give cross sections accurate enough for a reliable interpretation of the experiments. From a comparison of the few theoretical cross sections already obtained with the experiments in gold at 125 Mev, very tentative conclusions about the nuclear charge distribution are drawn. It is pointed out that an analysis of results at two or more energies will be a much more sensitive test of possible charge distributions.
Phys. Rev. 124, 519 (1961). T105 J. M. Trischuk and E. Kankeleit, Nucl. Phys. A90, 33 (i967). T106 E. A. Plassmann and L. M. Langer, Phys. Rev. 96, 1593 (i954) .
The ratio of the (y,n) photodisintegration cross section to the (e,e'n) electrodisintegration cross section for the isotopes Cu 63 , Zn 64 , Ag 109 , and Ta 181 was measured for electron energies of 24 to 35 Mev. This ratio was found to decrease with energy in contrast with the Weizsacker-Williams approximation which predicts a constant ratio. However, the Weizsacker-Williams method does yield a result which is of the right order of magnitude for Cu, Zn, and Ag and which is within a factor of two of the observed value of Ta.Assuming approximately one-half of the total photon absorption of nuclei to be attributed to the (y,n) reaction, then comparison of the experimental results for Cu, Zn, and Ag with calculations of Blair is consistent with the suggestion of Bethe and Levinger that the main absorption mechanism of nuclei for photons is electric dipole with a contribution of ^6 percent electric quadrupole absorption. However, for Ta no simple correlation between experiment and theory was found. This is attributed to a failure of the Born approximation used in the Blair calculations.
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