Thus, while the “Atomic Age", in cerms of military use, tecnrli739
a=
Pas
Caiady Degas 1... tne test of & plutonium (Pu
)
bomb at Alamagordo,
sew tlexico on July 16, 1945, it was officially and publicly berun
in August when,in the first use of atomic devices against civilian
populations, roughly 50 pounds of fissionable material killed over
100,900 men, women and children and injured another 100,000 more
at Hiroshima and Nagasaki in just a few minutes.
At 2:45 a.m. local time on August 5, 1945 the 8-29 Enola
Gay lumbered off the runway on the Micronesian island of Tinian,
now a part of the Mariana Islands District of the Trust Territory
of the Pacific Islands.
was the "Little Boy,''
In the cold, metal belly of the plane
uranium bomb, so called because of its
smaller size in comparison to the larger size of the ‘Fat Man"
plutonium bomb.
The firing mechanism of this “Little Boy" bomb
was deceptively simple.
gun barrel.
{(U
235
-).
The heart of the device was a special
At one end was a “bullet” made of refined uraniun
«At the other end was the “target' a Large lump of U
estimated to be about 5 kilograms, or 11 pounds.
235
As long as the
bullet’ and the "target'’ remained apart, nothing could happen.
But when the bullet was fired into the target, the amount of
235
*
U
occupying the same place became critical and the terribly
destructive enerpy of the tiny atom was unleashed.
At 08:15 on that day over IJiroshima, the Enola Gay's bomb
"Critical means that the amount of material was large enough
to automatically cause a violent chain reaction.
This is one of the
unique qualities of radioactive material.
Such reactions cannot
take place in nature in unrefined uranium ore, but after refinement,
are possible.
44
1014b50