be an isotopic spin forbidden El from the 3 -state; the 1.72-Mev line would similarly be an isotopic spin forbidden El from the 0+ state. 19 However, the 0+ member would be formed via a first forbidden transition from N 16 while the 3-would result from an allowed transition. Hence, the 1.72-Mev to 2.75-Mev intensity ratio would be greatly decreased following N 16 decay as compared with F+p if the doublet assumption were valid. This is contrary to observation. The unlikelihood that our new state is a single 3-(alpha-particle model) state has already been discussed.We should now like to make a general comment on the situation as regards the comparison between the alpha-particle model of O 16 and experiment. So far, attention has centered on the agreement in energy between the theoretical and experimental levels; but if the model is to be acceptable it must also give an adequate account of the dynamical properties of the states. In particular, we should ask what the model has to say about the reduced alpha-particle widths. These show experimentally a very wide range from 0.15 percent of the Wigner limit for the 2+ state at 19 The need to investigate this alternative explanation has been particularly stressed by Professor H. T. Richards. S EVERAL investigators 1 "" 4 have recently reported measurements of differential elastic scattering cross sections for medium energy neutrons and have compared their results with the theoretical approach of Feshbach, Porter, and Weisskopf. 5 These experiments have been confined to the energy region 1-5 Mev. In order to examine the applicability of this theory to higher energy neutrons, the present study of the differential elastic scattering cross sections of selected f A portion of a dissertation submitted to the Graduate Faculty of the University of Maryland in partial fulfillment of the requirements for the degree of Doctor of Philosophy. 1 M. Walt and H. H. Barschall, Phys. Rev. 93, 1062 (1954). 2 S. C. Snowdon and W. D. Whitehead, Phys. Rev. 94, 1267 (1954). 3 M. Walt and J. R. Beyster, Phys. Rev. 98, 677 (1955). 4 Jennings, Weddell, Alexeff, and Hellens, Phys. Rev. 98, 582 (1955). 5 Feshbach, Porter, and Weisskopf, Phys. Rev. 96, 448 (1954).9.84 Mev to 85 percent of the Wigner limit for the 1-state at 9.58 Mev. Although one could not hope that the model would give a detailed account of the widths, it must at least predict allowed transitions for those states that show experimentally large reduced widths and forbidden transitions for those with very small widths. Unless such qualitative correspondence emerges between theory and experiment for the dynamical properties of the states the present agreement in energy must be regarded as largely fortuitous. It would also be very valuable to know the predictions of the alpha-particle model in relation to radiative widths. It appears probable 20 that the predicted lifetime of the alpha-particle model against pair emission from the 0+ state at 6.06 Mev is too short by a considerable factor. Again the emission of El radiation from the...