the trinity test (july 16 1945)

late spring of 1945

• the manhattan project was approaching the finish line

• u-235 prod. at oak ridge & plutonium at hanford was progressing well

• one of each bomb were expected to be ready by the end of july

plutonium insecurities

making the imposition assemblies needed to detonate plutonium was still difficult and uncertain.

• project leaders made plans to conduct a full-scale test of a plutonium implosion device (the gadget) in new mexico in july 1945

“the gadget”

The nickname for the plutonium implosion device tested during the Trinity test in New Mexico, designed to demonstrate the feasibility of a nuclear weapon.

trinity test

took place on july 16th 1945 and proved far more successful than almost had expected, with an explosive yield of about 16 kilotons

leahy & the trinity test

was convinced right up to the test that atomic bombs would not work; speaking as “an expert on explosives,” he declared that they would be “no better than cordite”

little boy u-235 gun-type bomb

project leaders were so confident that the bomb would work that they made plans to drop the first bomb on japan as soon as it was ready, without having a test-fired one

how come there was not test trial for the u-235 bomb

production of u-235 was so slow that a second little boy bomb would not be ready until several months later

implosion process

the process needed to detonate plutonium was so difficult and uncertain that project leaders planned to conduct a test firing in july 1945

fat man bomb expectations

project scientists expected the first implosion bombs to be so much less powerful than the gun-type little boy bomb — perhaps 1 to 5 kilotons compared to the 10-15 kilotons expected from the little boy bomb.

hopes for the fat man implosion bomb

if the implosion bomb were to work well, it would be far more efficient than the gun-type design and would make it possible to produce many more bombs from the u-235 and plutonium being produced at oak ridge and hanford

trinity test site

it is about 180 miles south of los alamos, in an area known as the jornada del muerto

• the manhattan project took over the site in the summer of 1944 and began erecting test facilities in march 1945

“jumbo”

a giant containment vessel that groves ordered but decided not to use.

• groves originally thought to blow up the bomb within the steel containment, which would’ve been a bad idea.

george kistiakowsky

was head of the explosive division at los alamos and was responsible for the development of the complex explosive lenses for the implosion weapon

the “initiator”

designed to deliver a burst of neutrons to jump-start the chain reaction in an atomic bomb

• at the start of the implosion, the radioactive polonium would mix with the beryllium, bombarding it with alpha particles and causing the beryllium to release neutrons

detonators and the gadget

all of the detonators had to be set off at exactly the same moment, requiring extremely precise circuitry.

gadget core

at the center of the gadget lay the plutonium core; which weighed about 13.5 lbs and was a little larger than a softball

• it was surrounded by a heavy tamper made of ordinary uranium metal (mostly u-235)

trinity test observation stations

1. oppenheimer supervised the test from the south shelter (10,000 yrds from the zero point)

2. groves, bush, and conant onserved from the base camp, about 4 miles further southwest

3. hans bethe, ernest lawrence, and others from los alamos watched from campania hill, about 10 milles NW of the zero point

jack aeby

was a soldier (SED) assigned t emilio segre’s unit from los alamos and he took the only colored photograph of the trinity test

trinity test expectations vs. reality

though officially expected to yield from 1-5 kilotons, the trinity device in fact had an explosive yield of around 18 kilotons,

• what had been expected to be the “small bomb” turned out to be more powerful than the gun-type little boy bomb

trinity test fallout

a plume of fallout drifted NE from the test site over sparsely populated parts of New Mexico.

• most of the radioactivity dissipated fairly quickly, but some of it lingered; residents were not told anything about the danger

oppenheimer infamous quote

he later said that on seeing the fireball of the trinity test, he remembered a line from the bhagavad-gita: “now i am becoming death, the destroyer of worlds”

oppenheimer and groves publicity stunt

the two, accompanied by reporters and photographers, returned to the trinity site on september 9th 1945 in part to show the public that it was not dangerous

july 30th 1945 memo

general groves told general marshall that implosion bombs would be available about every ten days from late august, rising to one a week by november and “decidedly” more in early 1946.

• he also said changing cores could increase the number of bombs available before november but advised against doing so “until the effects of the present bomb are determined”

hiroshima

was struck by a little boy uranium gun-type bomb on the morning of august 6th, 1945 just 21 days after the trinity test of the very different plutonium implosion “gadget.”

nagasaki

a plutonium implosion fat man bomb was dropped on nagasaki just three dyas later on august 9th 1945.

• plans called for any subsequent bombs to be more of the efficient implosion desin