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The Third Shot
Core is prepped and assembly of bomb begins
Implosion type bomb similar to Fat Man
expected drop date 08/24/45
4 days gained during manufacturing, drop moved up to 08/17 -
The Begining
Plutonium from Hanford sent to Los Alamos
Third plutonium core manufactured (1st used in trinity test, 2nd was dropped on nagasaki)
Destined to be 3rd bomb used in Japan
Two plutonium-gallium hemispheres joined by a ring
Core is 3.5 in across, weighing 14 lbs
Nickname: Rufus -
V-J Day
Japan surrenders - Emperor Hirohito accepts terms of Potsdam Accord
Third bomb no longer needed
Core retained at Los Alamos for further experimentation -
The First Incident
Harry Daghlian was attempting neutron reflector experiments with the core
Accidentally dropped a tungsten carbide brick on the core causing supercriticality
The supercritical core emitted a neutron burst, dosing both Daghlian and a nearby security guard -
The Fate of Harry Daghilian
Harry Daghilian dies
Received 2 Gy neutron and 1.1 Gy gamma radiation dose
Official cause of death: acute radiation syndrome, hematopoietic focus -
The Second Incident
Louis Slotin demonstrated technique to measure criticality state by lowering neutron reflector onto the core
Slotin used a screwdrver and an unapproved technique to keep the two reflectors apart, preventing a supercriticality
On the day of the accident the screwdriver slipped, allowing the reflectors to encapsulate the core causing a supercriticality
All seven staff members in the room noticed a blue flash
Richard Feynman once described this experiment as "tickling the tail of a sleeping dragon" -
The Fate of Louis Slotin
Louis Slotin dies
Received 10 Gy neutron and 1.14 Gy gamma radiation dose
Official cause of death: acute radiation syndrome, gastrointestinal focus -
Operation Crossroads
Core scheduled to be used for first test at bikini atoll
Core found to be to radioactive post Slotin accident
Rescheduled for use in third test in early march 1947 codenamed Charlie -
Charlie is Canceled
Operation crossroads canceled due to unexpected underwater radioactivity
Additionally support vessels unable to be decontaminated and personnel found to have received unacceptably large radiation doses
Radiation safety officer Dr, Stafford Warren cancels further testing, describe as "the only Army colonel who ever sank a Navy flotilla" -
The Fate of the Demon Core
Summer of 1946
Rufus given new nickname “Demon Core”
Demon Core melted down and recycled for use in other cores
This was not uncommon as plutonium cores were still rare and were actively being tinkered with by researchers -
Fallout from the Demon Core incidents
Procedures at Los Alamos changed:
No more hands on criticality experiments
All personal at least ¼ mile away and experimetns conducted by remote control machines.
Experiments monitored by remote TV cameras.