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SELF-CLEANSING SHOT. In this view the mush- 

 room cloud has risen considerably higher than the 

 altitude indicated in the preceding photograph. 

 The top of the mushroom is beginning to flatten 

 out somewhat; on the under side of the top spurs 

 of vapor have begun to form, extending down- 

 wards. The Test Able shot has been described as 



a "self-cleansing" shot since the bomb was dej 

 tonated in the air and the upward column of gased 

 served to remove most of the radioactive fission 

 products from the lower atmosphere. This "cleans- 

 ing action" was not experienced to the same ex- 

 tent in Test Baker, in which the bomb was deto- 

 nated underwater. 



