World War II Honoree
Civilian on the Home Front
Harry Daghlian, Jr.
Hometown
Waterbury, Connecticut
Honored By
Ralph Bozorth
Relationship
A Grateful American
He was an American physicist with the Manhattan Project which designed and produced the atomic bombs that were used in World War II. He accidentally radiated himself on August 21, 1945, during a critical mass experiment at the remote Omega Site of the Los Alamos laboratory in New Mexico and died 25 days later from the resultant radiation poisoning. Daghlian was irradiated as a result of a criticality accident that occurred when he accidentally dropped a tungsten carbide brick onto a 6.2 kg bomb core made of plutonium gallium alloy. This core, subsequently nicknamed the “demon core", was later involved in the death of another physicist. During an experiment on August 21, 1945, Daghlian was attempting to build a neutron reflector manually by stacking a set of 4.4-kilogram (9.7 lb) tungsten carbide bricks in an incremental fashion around a plutonium core. The purpose of the neutron reflector was to reduce the mass required for the plutonium core to attain criticality. He was moving the final brick over the assembly, but neutron counters alerted Daghlian to the fact that the addition of that brick would render the system supercritical. As he withdrew his hand, he inadvertently dropped the brick onto the center of the assembly. Since the assembly was nearly in the critical state, the accidental addition of that brick caused the reaction to go immediately into the prompt critical region of neutronic behavior. This resulted in a criticality accident. Daghlian reacted immediately after dropping the brick and attempted to knock the brick off the assembly without success. He was forced to disassemble part of the tungsten-carbide pile in order to halt the reaction Daghlian was estimated to have received a heavy dose of radiation. Despite intensive medical care, he developed symptoms of severe radiation poisoning. His sister and mother were flown out to care for him; however, he fell into a coma and died 25 days after the accident.