52 NEUTRONS AND THEIR SPECIAL EFFECTS 



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GENERAL REFERENCES 



Bethe, H. A., Elementary Nuclear Theory, John Wiley, 1947. 



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DISCUSSION 



ZiRKLE : 



Solomon has pointed out that, when thermal neutrons bombard average 

 animal tissue, about eight are captured by hydrogen for each one captured by 

 nitrogen. I should like to add a note about the relative amounts of radio- 

 biological action due to these two capture processes. The additional factors to 

 be considered are: 



(a) The relative amounts of energy carried by the ionizing agents. The gamma 

 photon emitted by H^ (n, 7) H^ is 2 mev; the proton and the C^^ nucleus re- 

 sulting from N^^ (w, p) C^'* share about 0.6 mev. Accordingly the hydrogen 

 reaction predominates in energy by roughly 4 to 1. 



(6) The relative biological effectiveness {RBE) of the ionizing particles. This 

 varies widely among various radiobiological actions, but, as a rough average. 



