98 Dahlgren 



This was called the Trinity Test, designed to determine if a weapon could be 

 built from fissionable material. Once this was determined, Sandia Corporation 

 was established imder the Atomic Energy Commission in Albuquerque to take 

 care of weaponizing the device. They had contracts with the University of 

 California. 



There were two primary laboratories built in the West then — one at Los 

 Alamos, New Mexico, and one at Livermore, California. People were told when 

 they went there that these facilities were functions of the University of Califor- 

 nia, but actually these were the laboratories run by people like Oppenheimer 

 and Teller.* These were the real weapons-building laboratories. Several 

 people from Dahlgren went to those laboratories. Dr. [Norris E.] Bradbury, 

 who was for many years Technical Director at Los Alamos, was a Naval Reserve 

 officer at Dahlgren. I think Dr. Bradbury left there soon after the first atomic 

 device was tested in Alamogordo, and I believe he participated in building the 

 two devices used in Japan. Admiral Ashworth,** who was a Commander when 

 he was at Dahlgren, I believe was also theChief Weaponeer on one of the drops 

 in Japan. The reason these people were pulled out of Dahlgren was that 

 Dahlgren was considered to be the Navy's primary gun laboratory, and the first 

 atomic device used in Japan was a gun-type weapon. They needed somebody 

 experienced in naval gunnery to help put this device together because it was 

 essentially a gun. 



There are several ways to build atomic weapons, and this is no secret. One is 

 to physically separate, by a safe distance, two subcritical masses of fissionable 

 material. These must be assembled quickly and held together, at least for a 

 short period of time, as a critical mass that starts a certain fissionable process 

 and the atomic reaction. One way to do this is to shoot one subcritical mass at the 

 other — the gun against the target, so to speak, or a projectile against a target. Of 

 course there have to be all sorts of associated safety devices, but this was 

 essentially the first type of weapon. 



Another way to create an atomic device is to take a critical mass and make a 

 hollow sphere out of it. Because of the space it occupies from the hollow in the 

 center, it interacts subcritically. Then this mass is assembled by being driven 

 inward and is called an implosion device. Instead of explosion, where things go 

 out, implosion makes things go in. A layer of explosive is placed on the outside 

 of the hollow sphere. The major factor is to have a sufficient number of 



*Dr. Edward Teller, called "the father of the hydrogen bomb," worked on the development of the 



atomic bomb at Los Alamos, New Mexico, with Dr. Robert J. Oppenheimer, the wartime director 



of the Los Alamos laboratories. 

 *Vice Admiral Frederick L. Ashworth served at Dahlgren in 1944 as Senior Aviator and was 



bombardier in the bomber that dropped the second atomic bomb used in warfare on Nagasaki, 



Japan. 



