BOMBS AT BIKINI 



thick steel wall. Beta rays are particles. Specificall.y 

 they are light-weight negatively-charged particles 

 called electrons; they can scarcely penetrate a sheet 

 of cardboard. Alpha rays are heavier particles and 

 carry positive charges; they too have little penetrat- 

 ing power. Neutrons are uncharged particles; be- 

 cause of their lack of charge they are slippery, hard 

 to stop. They can penetrate several feet of steel. 



In preparing for A-Day, Colonel S. L. Warren and 

 other experts of the Radioactivity Group focused their 

 attention on a period of one minute. They knew that in 

 the A-Day Test, where the bomb was to be detonated 

 in the air, the great bulk of the materials producing 

 nuclear radiations would be carried upward by the 

 fireball and the mushroom. Only during the first 

 minute would the nuclear radiations be of outstanding 

 intensity.* 



There was no mystery as to the source of the nuclear 

 radiation. It was known that the fission products 

 would be highly radioactive.! Fission product s, of 



* It was expected that on B-Day, when the homb was set off 

 underwater, the materials emitting nuclear radiations would he 

 trapped in the water and would present a prolonged menace. Prep- 

 arations for this more complicated situation are discussed in a 

 later chapter. 



t Fissionable materials themselves can, of course he injurious. 

 The Smyth Report states that among materials which are radio- 

 active or toxic are to he listed not only fission products but uranium 

 and plutonium themselves; uranium, aside from its radioactive 

 properties, is poisonous chemically, and plutonium is alpha-radio- 

 active. 



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