Suppose that a reactor consists of two materials—the rst material has an absorption cross section of 1 cm−1 and a ssion cross section of 0.5 cm−1 . The second material has an absorption cross section...

Suppose that a reactor consists of two materials—the rst material has an absorption cross section of 1 cm−1 and a ssion cross section of 0.5 cm−1 . The second material has an absorption cross section of 0.25 cm−1 and a ssion cross section of 0. If half of the reactor consists of material 1 and half of the reactor consists of material 2, what must be the minimum value of ν for the reactor to be exactly critical? Assume that no neutrons leak out of the core.