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NUCLEAR OPTICAL MODEL CALCULATIONS.
Engineering technical rept.,
CALIFORNIA UNIV LOS ANGELES
Pagination or Media Count:
The purpose of this article is to review the methods used in optical model calculations including automatic search techniques, and to indicate how to speed up the computations while retaining desired accuracy in the results. All the formulas are presented which are required to compute the final quantities of interest i.e. the differential elastic scattering cross sections, polarizations and total reaction cross section for particles of spin 0, 12 and 1 incident against 0-spin targets. The numerical solutions of the radial Schroedinger differential equations are discussed in some detail as these calculations represent an important part of the total computation. The equations are usually solved by the Runge-Kutta, Cowell or Noumerov methods which are subject to a local truncation error and can be programmed quite easily. These methods are compared with respect to speed and accuracy. The final errors in the coefficients of the scattering matrix are discussed and illustrated for a typical test case. Several methods for automatically searching over the parameter space for the best fit to the experimental data are described and compared, and a recommended search program is presented for which the estimated computing times and storage requirements on an IBM 7094 Mod I computer are given. Author
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