Angry in the Great White North

From CNN:

Hundreds of doves were released in Peace Memorial Park in Hiroshima Saturday as tens of thousands of people gathered 60 years after the world's first atomic bomb was dropped on the city, killing nearly half of its residents.

From the web site of the US Democratic Party:

On August 6, 1945 our world changed forever when the United States dropped the first atomic bomb on the people of Hiroshima, three days later the act was repeated on Nagasaki.

From the BBC:

The Japanese city of Hiroshima has marked the anniversary of its destruction by the world's first atomic bomb 60 years ago.

From the CBC:

Three days after Hiroshima was decimated, a second bomb hit Nagasaki. Japan surrendered on Aug. 15, ending the Second World War.

What do all these stories have in common? They all state, or suggest, that the Hiroshima bomb, known as Little Boy, was the first atomic bomb constructed and detonated.

Of course, this is not true. The Little Boy bomb was a "gun-type" bomb, in which a projectile of highly enriched uranium is fired down a tube at a target plate, also made of uranium. As they collide, the impact surface of the projectile and the target compress, and uncontrolled nuclear fission occurs.

The design is simple, and the Little Boy bomb was the first of its kind, and was dropped on Hiroshima untested. The design is also inefficient, as much of the potentially fissile material behind the immediate contact surfaces is blown away. The physics of the process also require a longer bomb casing for the tube assembly. A plutonium-based gun-type bomb would have required a 19-foot-long tube. A plutonium-based bomb with this design would not have been able to fit inside the bomb-bay of a B-29, hence the far-less powerful uranium-based device (which could use a much shorter tube).

A more efficient design, both in space requirements and in explosive power, is an implosion bomb. A sphere is constructed with explosives arrayed on the inside surface, aimed inwards. The core of the sphere is fissile material (in this case, enriched plutonium). The detonation of the explosives compresses the core from all directions, creating a far more efficient fission reaction. The Fat Man bomb dropped on Nagasaki was such a bomb, and was an order of magnitude more powerful than Little Boy.

The problem with the implosion design is the complexity. The timing of the explosions has to be precise, or else the compression is off centre, and the core might be ejected prior to fission occurring. To test the complex design in order to ensure that Fat Man did not turn out to be a dud, a prototype bomb, known as "the gadget", was exploded at the Trinity test site at the Alamogordo Bombing Range in New Mexico, on July 16, 1945.

"Gadget" was the first atomic bomb detonated.

Here is the photograhic evidence.

First, a picture of the gadget:

Next, a picture of the Trinity explosion:

Not all the news stories get this wrong. Most in fact quite rightly use phrasing like "first atomic bombing" or "first atomic bomb used in conflict". The desire seems to be to work in the word "first". Far be it from me to question how the importance to a story about the atomic bomb attack on Hiroshima could be somehow diminished by using the word "second", but assuming it could be rendered less important, more editors could at least make an effort to use "first" in a historically accurate way.