Conversation so far:
What was the critical accident?
At 3:20 p.m., the screwdriver slipped and the upper beryllium hemisphere fell, causing a "prompt critical" reaction and a burst of hard radiation.
How bad was the injury?
the scientists in the room observed the blue glow of air ionization and felt a heat wave.
Slotin experienced a sour taste in his mouth.
Did slotin recover?
he had already been exposed to a lethal dose of neutron radiation.

Question: When did he die?
Self-contained rewrite: When did Louis Slotin die?