Neutrons are subatomic particles that, along with protons, make up an atomic nucleus. They are neutral particles without an electric charge and can penetrate barriers that block gamma rays. In some respects, neutrons can be considered the most powerful form of radiation.
On August 21, 1945, the first person on Earth to be severely irradiated by neutrons was Harry Dagglian. He sustained 5,100 millisieverts of neutron radiation and died 21 days later. Dr. Louis Alexander Slotin was by his side, watching his friend struggle painfully on the verge of death for three weeks.
