BOMBS AT BIKINI 



of the great damage caused by the shock wave, heat 

 flash, and gamma radiation. 



The gamma radiation's maximum power was dis- 

 played in the periods of a few seconds. Geiger count- 

 ers on target vessels demonstrated that an enormous 

 burst of gamma radiation was produced during the 

 instant when the bomb was detonating; additional 

 gamma radiation came from the fission products in the 

 fireball. But after the mushroom had borne its poison- 

 ous pall to high altitude the gamma radiation at sea 

 level was very weak indeed. 



The total amount of gamma radiation reaching the 

 target vessels was large. In many instances the photo- 

 graphic film gages showed aggregate dosages of the 

 order of hundreds or thousands of roentgens.* The 

 total output of gamma radiation was so great that if 

 by some feat of magic it could have been distributed 

 uniformly among several million persons it would have 

 eventually killed or seriously injured all of them. Of 

 course, in any practical situation the number of per- 

 sons affected would be very much smaller. 



The gamma radiation was of many wavelengths, 

 covering an appreciable spectral band. The typical 



* The roentgen is a unit of cumulative intensity of ionizing 

 nuclear radiation. Radiation which is sufficiently intense and pro- 

 longed to produce a hillion ion pairs in a single cubic centimeter 

 of air represents approximately one roentgen. One tenth of a 

 roentgen was adopted hy Joint Task Force One as the maxijnum 

 safe dosage per day. Fifty or 100 roentgens per day can he seri- 

 ously harmful to man, and a few hundreds roentgens may prove 

 fatal. 



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