-
- RD Program during WWII to produce nuclear weapons
- Responsible for the development of the Fat Man and Little Boy bombs that were dropped on Japan, ending the war in the Pacific
- In addition to the two bombs the US used, there was a third core made of 14lbs of Plutonium named "Rufus."
-
- Japan announces its intent to surrender
- Scientists given permission use Rufus, a 3.5" 14lb sphere of plutonium, to test the limits of nuclear material
- Scientists at the Los Alamos National Laboratory begin experimenting with Rufus to better understand the limit between the subcritical and critical state
-
- Physicist Harry Daghlian performed an experiment using tungsten carbide bricks to surround Rufus.
- The bricks would act as neutron reflectors, decreasing the subcriticality of the plutonium.
- Physicist Richard Feynman described such experiments as "Tickling the Tail of a Sleeping Dragon."
-
- Harry was able to stack the tungsten carbide blocks until his measurements indicated that Rufus was only slightly sub critical
- Realizing that the block he was placing on his reflector shell would be the final straw that pushed Rufus to a critical state, he began moving the block away from the core
- Unfortunately, Harry accidentally dropped the final block and it landed on the core, immediately putting Rufus into a critical state
-
- Though Harry quickly removed tungsten to stop the reaction he received an estimated 404rem of neutrons.
- Harry was hospitalized for Acute Radiation Syndrome where he initially had symptoms similar to a bad stomach bug
- His symptoms improved for a few days before rebounding with extreme severity ending in coma and death 25 days after his exposure
-
- After Harry's death, Canadian physicist Louis Slotin began conducting similar experiments with Rufus
- His approach involved using two beryllium half spheres as neutron reflectors that he would bring together using a screwdriver to help keep space between them
- He was warned about his approach to critical assemblies by his boss Enrico Fermi who said "You'll be dead within the year if you keep doing that."
- A few months later Louis died because of a second criticality accident involving Rufus
-
Going critical
-
- 9 months after the Harry's accident, Louis Slotin was giving a tour to Alvin Graves, the scientist would be replacing him
- Alvin saw the critical assembly (Rufus) and commented that he had never seen it demonstrated before
- While demonstrating the experiment, the screwdriver slipped and the two reflectors fell together, completely enclosing the plutonium and causing a prompt criticality event
- Knowing he had received a lethal dose of radiation, Louis simply said, "Well, that does it."
-
A legacy The next tuesday 21
Same hospital bed -