Consider a plane of thickness $$\mathrm{\Delta }z$$. The plane emits $$q$$ neutrons per second per unit area at a single energy and is comprised of a pure absorber. What is the angular flux at the right edge of the plane, $$\mathrm{\Phi }(\mathrm{\Delta }z,\mu )$$? Use your solution to give the angular flux emerging from an infinitely thin plane source. Hint: Use an integrating factor of $$\exp (\sigma z/\mu )$$.

The derivation of this solution is after the jump

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