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We undertake herein to derive the Wigner-Wilkins [W-W] neutron/nucleusscattering kernel, a foundation stone in neutron thermalization theory, on thebasis of a self-contained calculation in quantum mechanics. Indeed, aquantum-mechanical derivation of the W-W kernel is available in the literature,cited below, but it is, in our opinion, robbed of conviction by being couchedin terms of an excessive generality. Here, by contrast, we proceed along aself-contained route relying on the Fermi pseudopotential and a first-orderterm in a time-dependent Born approximation series. Our calculations are fullyexplicit at every step and, in particular, we tackle in its every detail afinal integration whose result is merely stated in the available literature.Furthermore, and perhaps the most important point of all, we demonstrate thatthe quantum-mechanical W-W kernel outcome is identical down to the last iotawith its classical antecedent, classical not only by virtue of historicalprecedence but also by being based on classical Newtonian mechanics.

Wigner-Wilkins neutron/nucleus scattering kernel quantum-mechanically derived