Study of (d, α) Reactions on Some Light Nuclei

Abstract

533Similarly, though Ni 58 and Ni 6() are comparable feature for feature below 75°, thereafter they appear to diverge (or for Ni 58 <cr for Ni 60 ). It should be cautioned, however, that it. is difficult to compare these elements without some quantitative analysis that would clearly describe in what sense these elements tended to be equivalent. For example, one would expect a Rutherford normalization to be a valid physical representation only at forward angles.The over-all changes expected on the basis of simple arguments are evident from the data; i.e., the way in which the ratio <r(experimental)/c7 (Rutherford) varies with A (see Fig. 14), and the way 0; varies with A.The practical results of the experiments are, then, that the general features are not greatly changed by using naturally occurring isotopes as targets. Only if one is seeking yet finer effects than the present measurements allow, could this be an important factor. The optical P 1IYSICAL R K VIEW The angular distributions of the charged particles from the W A {d,d)W\ N 14 (^,a 0 )C 12 , N 14 (^«i)C 12 *, and N 15 (d,ao)C 13 reactions have been studied with a deuteron bombarding energy of 21 Mev. The chargedparticle groups are identified and their energy is measured by a dE/dX vs E counter telescope. The N(</,a)C angular distributions and the O l6 (d,a)W 4 angular distribution measured by Freeman tie et al. have been compared with theoretical curves calculated from a simplified direct-interaction model. The relative magnitudes of the experimentally determined cross sections have also been compared with theory. The results indicate that the O u (d,ao) reaction can be described by the compound-nucleus extreme, while the N 14 (d,«0 process appears to favor description by a direct-interaction model. The remaining (d,a) reactions are intermediate cases.

Properties of Excited States inC14

“…We have calculated these using harmonic-oscillator radial wave functions which have a radial fall-off of the form exp (-%yr 2 ). We shall follow Vischer and Ferrell 24 and take 7-1/2 =1.68 F. The y~2 in the expression for A (E2) are in fermi, 4 i.e., we take y~2= 7.9659. We shall evaluate EL radiative widths using the weak surface coupling approximation which endows the neutron with a charge 0z,e in an electric transition of order L. The degree to which this procedure is justified is not too clear; however, it caricatures the effects of the contribution to A(E2) from admixtures of higher shells and has provided a simple and quite consistent method of explaining the fact that £2 and E3 transitions are usually stronger than the predictions of the independentparticle model.…”

“…There are now definite spin and parity assignments for all the bound levels of C 14 with the exception 5,18 -19 of the 7.01-MeV level which is expected 4,22 to be /* = 2+. The predominant shell-model configurations of these states are also known 21-23 and we would now like to compare the experimental information pertaining to electromagnetic transitions from these states with the predictions of the shell model.…”

“…The bound odd-parity states of O^4 belong predominantly to the configuration s A p 9 (2s,ld), while the 0 + ground state and 0 + 6.59-MeV level are 22,23 mixtures of s 4 p 10 and s 4 in the odd-parity states. However, a full theoretical treatment of such admixtures would be quite difficult indeed and those theoretical estimates which have been made indicate that these admixtures are not large.…”