Sec. 5.6] NEUTROXS 135 



1 - HKX/R) + (X/L)] 

 7 " 1 + %[(A/*) + (X/L)] 



where X = mean free path in reflector = 1/Na 

 L = diffusion length 

 The value of y increases with R and for R — > co becomes the albedo for a 

 plane boundary 



1 - (2X/3L) 



7 



1 + (2X/3L) 



Material such as concrete is particularly useful for reflectors and also 

 serves as a barrier around moderators to reduce the health hazard to person- 

 nel working in the vicinity. 



REFERENCES FOR CHAP. 5 



1. Hughes, D.: Phys. Rev., 70, 219 (1946). 



2. Bloch, F., D. Nicodemus, and H. H. Staub: Phys. Rev., 74, 1025 (1948). 



3. Breit, G., and E. Wigner: Phys. Rev., 49, 519 (1936). 



4. Bethe, H: Rev. Mod. Phys., 9, 151 (1937). 



5. Bethe, H, and G. Placzek: Phys. Rev., 51, 450 (1937). 



6. Kapur, P. L., and R. Peirels: Proc. Roy. Soc. (London), 166, 277 (1939). 



7. Siegert, A. J. Y.-.Phys. Rev., 56, 750 (1939). 



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9. Feshback, H, D. C. Peaslee, and V. F. Weisskopf: Phys. Rev., 71, 145 (1947). 



