Postalo Vleeptron first issued this stamp on the 60th Anniversary of the atomic bomb dropped on Hiroshima, Japan.
"Tickling the dragon's tale" was what Los Alamos' scientists called this crucial and wildly dangerous experiment. The Big Unknown was the amount of fissile material which would spontaneously begin a flood of neutrons and the desired explosive chain reaction and unprecedented release of energy.
For this re-issue, we've learned a few things and corrected a few mistakes. In the original, we depicted a Geiger-Muller counter. Well, that wouldn't have done any good, because a Geiger counter can't detect neutrons, which possess no electomagnetic charge. So now we're using a scintillation counter as the neutron detector.
The Tickling experiment was frighteningly crude and was located in an outbuilding far from people. It used gravity to drop an ingot of fissile metal through a hollow cylinder of some more of the fissile material. Eventually they increased the mass of the falling ingot sufficiently to cause the desired neutron cascade. Gravity saw to it that the two fissile masses would only be in close proximity for a fraction of a second, after which the ingot would fall through the hollow cylinder.
In the Japanese names for the target cities, the rightmost ideogram means "city." Without this ideogram, the two leftmost ideograms refer to the prefecture, or county, or administrative district surrounding the city. It's somewhat like New York City, which is located in the larger New York State.
In 1945 the USA (partnered with UK and Canada) had the only nuclear weapons on the planet. A few years later, the Soviet Union detonated its first. In the early 1950s, US technology developed "the super," a fusion bomb most commonly called the hydrogen bomb -- far more powerful than the A-bombs. The Soviet Union soon followed.
Now a few of the sovereignties with either fission or fusion bombs, or both, are France, Peoples Republic of China, Pakistan, India, Israel (though they're keeping their bombs secret, don't tell anybody), North Korea, and much of the world is shitting bricks over Iran's nuclear intentions.
The next steps are possession of a nuclear weapon by a Non-State Actor (e.g. ISIS/ISIL) or a "dirty bomb" -- not much explosion or mass death, but whose radioactive release products would render a city or region uninhabitable for years or longer, like Chernobyl or Fukushima.
To date, Hiroshima and Nagasaki are the only two human population centers to be bombed by a nuclear weapon. Above, the Hiroshima Cenotaph erected at Ground Zero. 80,000 people died the day of the bombing, and within a year the toll had risen to an estimated 140,000. The Nagasaki bomb fell some distance from its center-city target, killed 73,884, and injured/sickened about the same number.
Imperial Japan surrendered unconditionally on 15 August 1945. The bomb had always been intended to be dropped on Nazi Germany, but Germany had surrendered by the time the bomb was successfully tested in the New Mexico desert. The first war bomb was shipped instead to the island Tinian in the Pacific, within bomber range of the home islands of Japan.
