Angular momentum dependence of the absorptive optical potential

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Abstract
It is shown that the expected nonlocality in the imaginary optical potential implies a dependence on the projectile orbital angular momentum l. First, as a model of this effect, a potential with a Gaussian dependence on the nonlocal coordinate is expanded in multipoles, and the local equivalent potential is calculated using the Perey-Saxon method. It is shown that the local approximation tends to compensate for the falloff with l of the multipole expansion because of the smaller local radial wave number for higher l values. The l dependence of the resulting local equivalent potential depends fairly sensitively on whether or not the assumed Gaussian nonlocality is spherical. For a nonlocality that is greater in the angular direction than in the radial direction, there is a distinct residual falloff of the local-equivalent potential with l. Second, the local approximation has also been made to the l-dependent nonlocal potential resulting from the microscopic nuclear structure approach to the imaginary optical potential. It is found that although there is a considerable falloff of the imaginary optical potential with angular momentum as in the Gaussian model, the l dependence is somewhat erratic.