Samuel Cohen was the American physicist who developed the neutron bomb, a small nuclear device which has the ability to kill people, while causing little damage to buildings and other inanimate structures.
Cohen developed the "enhanced radiation weapon" for battlefield use at the height of the Cold War in 1958. The neutron bomb works by releasing a burst of neutron particles that can pass through tanks and buildings but will cause lethal damage to living cells.
While a conventional nuclear device leaves behind radioactive debris that can contaminate an area for years or decades, a neutron bomb's radiation quickly dissipates.
Cohen described his device as "the most sane and moral weapon ever invented" because "when the war is over, the world is still intact."
On the whole the world did not agree with him. Soviet leader Nikita Khrushchev condemned it as a "capitalist" weapon, built "to kill a man in such a way that his suit will not be stained with blood, in order to appropriate the suit," a theme taken up by peace campaigners in the West.
The neutron bomb became stigmatized as "the ultimate capitalist weapon," as if a bomb that only killed people in a limited area was somehow worse than a weapon that killed people across huge swaths and caused environmental devastation into the bargain.
A succession of American presidents rejected the technology, largely on grounds that it might escalate the arms race, before Jimmy Carter announced plans to deploy the warheads in 1978, only to back off following public protests.
The Reagan administration authorized production of 700 neutron warheads to counter Soviet tanks in Eastern Europe, but deployment was deferred in the face of anti-nuclear protests across Europe and the stockpile was scrapped by President George H.W. Bush. France, China, Russia and Israel are also thought to have produced neutron weapons, but it is not known if they still have any.
Samuel Theodore Cohen was born in Brooklyn, New York, on Jan. 25, 1921, the son of Jewish emigrants from Austria. When he was four the family moved to Los Angeles, where his father worked as a carpenter for the Hollywood studios. Samuel was a sickly child, prone to allergies and other ailments, and his mother put him on a rigid diet, regular purges and daily ice-water showers to toughen him up. She even controlled his breathing (believing it to be unhealthy to breathe through the mouth) and made him drink so much carrot juice it turned his skin yellow.
Despite her ministrations he survived and went on to be a brilliant student at the University of California, Los Angeles, where he graduated in 1943 with a degree in physics. He joined the army on graduation and was posted to the Massachusetts Institute of Technology for advanced training in Mathematics and Physics.
In 1944 he was selected to work on the Manhattan Project to develop the first atom bomb. He worked on Fat Man, the bomb dropped on Nagasaki in 1945, days after Little Boy destroyed Hiroshima, and was involved in calculating the likely densities of neutrons released on detonation.
After the war he studied for a doctorate at Berkeley before dropping out to join the Rand Corporation, where he continued his work on radiation fallout and developed the neutron bomb.
In later life he explained that the inspiration for the bomb came during a visit to Seoul in 1951. The city had been largely flattened by conventional shelling and bombing in the Korean War and he recalled a "lunar landscape" in which abandoned children drank from gutters filled with sewage. He wondered whether it might be possible to develop a nuclear device that could be deployed against battlefield formations, but would not shell and bomb cities to smithereens, wrecking the lives of their inhabitants.
Delivered by a missile or an artillery shell and detonated a quarter of a mile above ground, his bomb was designed to eliminate life in an area less than a mile across, avoiding wider slaughter and destruction. The military successfully tested the bomb in the Nevada desert, and over the next two decades Cohen campaigned for its deployment.
But from the first he faced opposition not only from peace campaigners but also from military contractors and senior service personnel with a vested interest in existing nuclear arsenals. Cohen claimed to have been awarded a peace medal by the pope, though he seemed to be unclear in which year it was awarded and whether it was John Paul I or John Paul II. Some doubted.
During the 1990s Cohen turned his attention to the dangers of a substance called red mercury which, he claimed, was capable of detonating a nuclear device as small as a baseball. He alleged that the Soviet Union had produced a number of "micro-nukes" based on the substance, 100 of which were in the hands of terrorists. Later he claimed that Saddam Hussein had taken delivery of about 50 of these devices, which he supposedly planned to use against coalition forces as they approached Baghdad. The claims were generally trashed by mainstream scientists, who dismissed red mercury as mythical, some suggesting that Cohen had been roped into a disinformation campaign by government agencies designed to lure potential terrorists into being captured.
Cohen wrote several books about nuclear weapons issues and a memoir, F-- You, Mr. President!: Confessions of the Father of the Neutron Bomb, published on the Internet in 2000.
He is survived by his wife, Margaret, and three children.