Several problems in one-speed neutron transport theory for spherically symmetrical systems are discussed. The singular eigenfunction expansion technique is used to construct a solution for a specific finite-slab Green's function. This slab solution is then used to construct the finite-medium spherical Green's function by extending the point-to-plane transformation concept. For the general case, the expansion coefficients are shown to obey a Fredholm equation, and first-order solutions are obtained; however, in the infinite-medium limit the solution is represented in closed form. In addition, the solution for the angular density in an infinite-medium due to an isotropic point source is developed directly from the set of normal modes of the transport equation. A proof that the result so obtained obeys the proper source condition at the origin is given.

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The dependence of the EPR spectrum of dislocations in deformed silicon on illumination with monochromatic light reveals the two EPR centers Si—K1 (S < 1/2) to be different ionization states of one and the same dislocation center. The energy level separating these ionization states lies near the middle of the gap. Photo‐EPR of p‐ and n‐Si demonstrates that extracting an electron from the single spin states Si—K1 transforms the dislocation center into a spin‐free state. It is assumed that the transition K1 → K2 is connected with a charge state stimulated structure change. In undoped silicon the relaxation of a light induced change of the dislocation charge is strongly inhibited below 140 K.

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