---------------------------------------
| |
| The Making of the Atomic Bomb |
| Richard Rhodes |
| |
|-------------------------------------|
| |
| Created: 08/16/2007 |
| |
| Last modified: 08/17/2007 |
| |
---------------------------------------
We must be curious to learn how such a set of objects - hundreds
of power plants, thousands of bombs, tens of thousands of people
massed in national establishments -- can be traced back to a
few people sitting at laboratory benches discussing the peculiar
behaviour of one type of atom.
Spencer R. Weart
The first subway on the European continent was dug not in Paris or Berlin,
but in Budapest.
On November 8, 1895, German physicist Wilhelm Rontgen discovered X-rays
radiating from the fluorescing glass wall of a cathode-ray tube. In 1897,
he identified what he called the "negative" corpuscle, the electron, and the
first atomic particle to be identified.
In 1898, Madamme Curie had discovered the radioactive element she called
Polonium, after her native country of Poland.
In 1907, Albert Einstein derived his famous equation E = MC**2.
If the speed of light is a constant, then something else must serve as the
elastic between two systems at motion in relation to one another - even if
that something else is time. If a body gives off an amount E of energy its
mass minutely diminishes. But if energy has mass, then mass must have energy:
the two must be equivalent: E = MC**2, E/C**2 = M (i.e. an amount of energy
E in joules is equal to an amount of mass M in kilograms multiplied by the
square of the speed of light, an enormous number, 3 x 10**8 meters per second
times 3 x 10**8 m/s = 9 x 10**16 or 90,000,000,000,000,000 joules per kilogram.
Dividing E by C**2 demonstrates how large an amount of energy is contained
even in a small mass.
In 1908, Hans Geiger and Ernest Rutherford devised the Geiger counter.
In 1914, H.G. Wells published the book "The World Set Free" and predicted
atomic bombs.
Out of the prospering but vulnerable Hungarian Jewish middle class came no
fewer than seven of the twentieth century's most exceptional scientists, in
order of birth, Theodor Von Karman, George de Hevesy, Michael Polanyi,
Leo Szilard, Eugene Wigner, John von Neuman and Edward Teller. The mystery
of such a concentration of ability from so remote and provincial a place has
fascinated the community of science. It was like a group of men from Mars had
arrived.
In October of 1918, Hungary suffered a revolution and the Republic of Hungary
was announced on November 16, 1918. On November 20, 1918, the Hungarian
Communist party formed and on March 21, 1919, the Republic of Hungary
bloodlessly metamorphosed into the Hungarian Soviet Republic. One hundred and
thirty three (133) days later, the White Terror of the Horthy regime moved in
and installed a violent fascist anti-semitic regime.
In 1918, Francis William Aston invented the mass-spectograph which sorted
elements and isotopes of elements by mass. It used mixed nuclei projected in
a radiant beam through a magnetic field which would bend into separated
component beams according to their velocity, which gave a measure of their
mass. An electrostatic field bent the component beams differently depending on
their electrical discharge which gave a measure of their atomic number.
In 1919, Ernest Rutherford achieved the first artificial transmutation
(sort of a split) of an atom.
In the summer of 1921, a wealthy seventeen-year-old American student,
Robert Oppenheimer was collecting minerals in Joachimsthal.
Oppenheimer did laboratory experiments in the third grade, begin keeping
scientific notebooks in the fourth, begin studying physics in the fifth,
though for many years, chemistry would interest him more.
In 1922, at age 14 he was sent to camp. When the camp director cracked down
on dirty jokes, the other boys, the ones who called Robert "Cutie" traced the
censorship to him and hauled him off to the camp icehouse, stripped him bare
beat him up - tortured him, his friends said - painted his genitals and
buttocks green and locked him away naked for the night. Responsibly, he
held out to the end of the camp but never went back. It was obvious to
everyone, that he was very different and brilliant.
A highlight of the camp was a pack trip to the Jemez Caldera where
Los Alamos, New Mexico was to be built as the center of development of the
first atomic bomb.
In 1922, Neils Bohr linked the atomic structure of an element with its
place on the periodic table, thus irrevocably linking physics to chemistry.
Around the nucleus, atoms are built up of successive orbital shells of
electrons, imagine a set of nested spheres - each shell capable of accomodating
up to a certain number of electrons and no more. Elements that are similar
chemically are similar because they have identical number of electrons in
their outermost shells, available there for chemical combination.
In 1922, a 20 year old Bavarian student named Werner Heisenberg questioned
Bohr's theories
In 1927, Fritz Houterman worked out a basic theory of stellar existence.
He noted that stars burn at temperatures of 10 million and more degrees and
have lifespans of billions of years - a prodigious and unexplained expenditure
of energy. At the high temperatures in the interior of a star, the nuclei in
the star could penetrate into other nuclei and cause nuclear reactions,
releasing energy. That energy would be released when hot (and therefore fast
moving) hydrogen nuclei collided with enough force to overcome their respective
electrical barriers and fused together, making helium nuclei and giving up
binding energy in the process. These reactions would be called thermonuclear
reactions because they occured at such high temperatures.
In February of 1927, Werner Heisenberg developed his uncertainty principle.
On the extremely small scale of the atom, there are inherent limits on how
precisely, events could be known. If you identified the position of a
particle, allowing it to impact a zinc-sulfide screen, you changed its
velocity and so lost that information. If you measured its velocity by
scattering gamma rays from it, perhaps, your energetic gamma ray photons
battered it into a different path and you could not then locate precisely
where it was. One measurement always made the other measurement uncertain.
Bohr pointed out that quantum conditions ruled on the atomic scale and
the limitation of our senses imposed necessary limitations on what we could
know.
Einstein has his personal insights into the gambling habits of the Diety.
Does God throw dice?
Ernest Rutherford used one nucleus to bombard another, but since both nuclei
were strongly positively charged, the bombarded nucleus repelled most attacks.
Szilard's design of a cyclotron-like particle accelerator would serve to
accelerate particles to greater velocities to force them past the nucleus's
electrical barrier.
On February 27, 1932, Rutherford announced the possible existence of a neutron,
a particle with nearly the same mass as the positively charged proton that
until 1932 was the sole certain component of the atomic nucleus. The neutron
had no electric charge which meant that it could pass through the surrounding
electrical barrier and enter into the nucleus. The neutron would open the
atomic nucleus to examination.
In 1936, Francis Aston delivered a lecture on the social consequences of
releasing atomic energy that was feasible from the equation E = mc**2.
"There are those who say that such research should be stopped by law,
alledging that man's destructive power are already large enough. So, no doubt,
the more elderly, and ape-like of our prehistoric ancestors objected to the
innovation of cooked food and pointed out the grave dangers attending the use
of the newly discovered agency fire. Personally, I think there is no doubt
that sub-atomic energy is available all around us and that one day man will
release and control it's almost infinite power. We cannot prevent him from
doing so and can only hope that he will not use it exclusively in blowing
up his next door neighbor.
American theoretical physicist Arthur Holly Compton, of the Compton effect,
determined that a proton is 1,836 times heavier than an electron.
In 1923, Arthur Holly Compton discovered that X-rays or light had a dual
nature and constituted both wave and particles (photons). He inadvertently
discovered the elastic scattering of a photon by an electron. This became
known as the Compton Effect.
In 1930, Princeton University acquired John von Neuman and Eugene Wigner
as a package deal.
In 1931, a German journalist had the temerity to ask Adolf Hitler where he
would find the brains to run the country if he took it over.
On August 2, 1932 an American experimentalist at Caltech discovered the
positron, an electron with a positive charge,
At noon on January 30, 1933, Adolf Hitler, forty three years old, gleefully
accepted his appointment as Chancellor of Germany.
On January 15, 1934, Joliot-Curies noted that artificial transmutations
might be of an explosive type. If such transmutations do succeed in
spreading in matter, the enormous liberation of useful energy can be
imagined. But he saw the possibility of cataclysm if the contagion spreads
to all the elements of our planet.
He had taken note that astronomers had noted stars that expanded quickly were
undergoing such cataclysmic transmutations.
At age 17, Enrico Fermi wrote an essay called "Characteristics of Sound"
which set forth the partial differentiation of a vibrating rod which Fermi
solved by Fourier analysis, finding the eigenvalues and eigenfrequencies...
which would have been creditable for a doctoral examination,
In 1926, at age 25 Enrico Fermi became a professor of theoretical physics
at the University of Rome.
On June 28 and July 4, 1934 Leo Szilard amended his patents indicating that
he saw the possibility of weapons in the transmutation of elements through
what would become known as a chain reaction. He described what would become
known as a "critical mass", the volume of chain-reacting substance necessary
to make the chain reaction self-substaining. The patent could be used in the
construction of explosive bodies, very many thousand times more powerful than
ordinary bombs
The nucleus was viewed as one large particle with a definite diameter which
a neutron could penetrate in 10**-21 seconds. Any capture process would have
to work within that brief interval of time.
On November 7, 1938, a 17 year old Polish Jewish student attempted to
assasinate Ernst vom Rath, third secretary in the German embassy in Paris
in reprisal for Polish mistreatment of the student's parents. Vom Rath died
on November 9 and the assasination served as an excuse for general anti-semitic
mobs. Mobs torched synagogues, destroyed businesses and stores, dragged
Jewish families from their homes and beat them in the streets. A volume of
plate glass was shattered that night across the Third Reich equal to half the
annual production of its original Belgian sources. This was KrystalNacht
(Crystal Night).
On December 19, 1938, Lisa Meitner received a letter from Ottho Hahn, age 59,
and Strassmann on their experiments with radium-actinium-lanthanum and
producing barium as a side effect. Otto Hahn was one of ablest radiochemists
in the world. They irradiated 15 grams of purified uranium with radium for
over an hour. If the radium was really radium (88), then by beta decay it
ought to transform itself one step up the periodic table into actinium (89)
but if it was barium (56), then by beta decay it ought to transform itself into
lanthanum (57).
On December 22, 1938 a copy of their findings were sent to Lisa Meitner and her
nephew Otto Frisch who were about to go on a short vacation in the Swedish
village of Kungalv. How could barium be formed from uranium or how could
a hundred particles be chipped away from a nucleus?
They pictured the uranium nucleus as a liquid drop that would oscillate when
struck by a neutron. In one of its oscillation, it might elongate. The strong
nuclear force operates over an extremely short distance, the electric force
repelling the two bulbs of an elongated drop would gain advantage. The two
bulbs would push further apart. A waist would form between them and the strong
force would regain its advantage within each of the two bulbs. It would work
like surface tension to pull them into spheres. The electric repulsion would
work at the same time to push the two separating sheres even farther apart.
(Try to envision how living cells divide to multiply their numbers.)
Lisa Meitner was saying that if you really do form two such fragments they
would be pushed apart with great energy by the mutual repulsion of their
protons at one-thirtieth the speed of light. Meitner and Frisch calculated
energy to be about 200 MeV: 200 million electron volts. An electron volt is
the energy necessary to accelerate an electron through a potential difference
of one volt. 200 MeV is not a large amount of energy but it is an extremely
large amount of energy from one atom. The most energetic chemical reactions
release about 5eV per atom. Ernest Lawrence was that year building a
cyclotron with a nearly 200 ton magnet with which he hoped to accelerate
particle by as much as 25 MeV. Frisch would calculate later that the energy
from each bursting uranium nucleus would be sufficient to make a grain of sand
visibly jump. In each mere gram of uranium there are 2.5 X 10**21 atoms, an
absurdly large number, 25 followed by twenty zeroes:
2,500,000,000,000,000,000,000.
It was at this point that Lisa Meitner remembered she had attended a lecture by
Albert Einstein where she had learned the formula E = MC**2 and made the link.
The concept of a chain reaction had still not been considered.
It was Otto Frisch who talked to a biologist William A. Arnold and asked:
"What do you call the process in which one bacterium divides into two?"
Arnold answered "binary fission". Thus the term "fission" came into play in
nuclear physics.
On January 16, 1939, Frisch's reports, titled
"Disintegration of uranium by neutrons: a new type of nuclear reaction" and
"Physical evidence for the division of heavy nuclei under neutron bombardment".
were sent to London. Neils Bohr had already discussed these issues with
them.
On January 25, 1939, Herbert Andersen, a graduate student replicated the
nuclear bombardment in the basement of Pupin Hall at Columbia University
in New York City. It was the first intentional observation of fission west
of Copenhagen.
George Uhlenbeck, who shared an office with Enrico Fermi at Columbia University
on Manhattan,overheard him when he was standing at his panoramic office window
high in the physics tower looking down the gray winter length of Manhattan,
its streets alive as always with vendors and taxis and crowds. He cupped his
hands as if he were holding a ball, he said simply, for once not lightly
mocking, "A little bomb like that, and it would all disappear."
In late January, 1939, the concept of a chain reaction was beginning to form
in everyone's mind. Szilard discussed his plan for voluntary secrecy on
fission.
If a neutron penetrated a uranium nucleus, the result might be fission. But
if the neutron travelled at the appropriate energy when it penetrated,
somewhere around 25 eV, the nucleus would probably capture it without
fissioning, Beta decay would follow, increasing the nuclear charge by one unit
and the result would be a new as-yet-unnamed transuranic element of atomic
number 93.
The uranium nucleus requires an input of about 6 MeV to fission. That much
energy was necessary to roil the nucleus to the point where it elongated and
broke apart.
On March 16, 1939, George Pegram wrote a letter of introduction on behalf
of Fermi to Charles Edison, the Undersecretary of the Navy.
"Experiments in the physics laboratory at Columbia University reveal that
conditions may be found under which the chemical element uranium may be able
to liberate its large execess of atomic energy, and this might mean the
possibility that uranium might be used as an explosive that would liberate a
million times as much energy as any known explosive. My own feeling is that
the probabilities are against this, but my colleagues and I think that the
bare possibility should not be disregarded".
The next afternoon, Fermi turned up at the Navy Department on Constitution
Avenue for his appointment with Admiral Hooper. He had probably planned
a conservative presentation. The contempt of the desk officer who went in to
announce him to the admiral encouraged that approach. "There's a WOP outside,"
Fermi overheard the man say. So much for the authority of the Nobel Prize.
Many physicists declared that it would be difficult, if not impossible to
separate Isotope 235 from the more abundant Isotope 238. The Isotope 235 is
only 1 percent of the uranium element. The process of separation would be
prohibitively expensive.
On July 30, 1939, Szilard started writing a letter, in German, to President
Roosevelt on behalf of Albert Einstein.
On September 1, 1939, at 4:45 a.m., Adolf Hitler ordered the invasion of
Poland. On September 16, 1939, German intelligence had discovered uranium
research abroad and Neils Bohr's paper (and conclusion)
"The Mechanism of Nuclear Fission".
The possibility of a critical mass is anchored in the fact that the surface
area of a sphere increases more slowly with increasing radius than does the
volume (as nearly r**2 to r**3). At some particular volume, depending on the
density of the material and on its cross sections for scattering, capture, and
fission, more neutrons should find nuclei to fission than find surface to
escape from: that volume is then the critical mass.
The critical mass of U238 was many tons.
Whatever scientists of one warring nation could conceive, the scientists of
another warring nation might also conceive - and keep secret. The nuclear
arms race started early 1939. Responsible men who properly and understandably
feared a dangerous enemy saw their own ideas reflected back to them
malevolently distorted. Ideas that appeared defensive in friendly hands seen
the other way around appeared aggressive. But they were the same ideas.
In December, 1939, Paul Harteck was building a Clusius separation tube in
Berlin. German uranium research was thriving.
Exporting gold from Germany was a serious criminal offense. Neils Bohr took
the time to save the Nobel Prize medals that Max von Laue and James Franck
had given him for safe keeping by dissolving the medals separately in acid.
As solutions of black liquid in unmarked jars, they sat out the war innocently
on a laboratory shelf. Afterward, the Nobel Foundation recast them and
returned them to their owners.
On June 12, 1940, Vannevar Bush spoke to Roosevelt about organizing the
National Defense Research Council (NDRC) which gave nuclear fission an
articulate lobby within the executive branch. In late June, the committee
was renamed the MAUD committee.
Franz Simon estimated the cost of a uranium separation plant in great detail
at five million pounds and it would generate one kilogram a day.
On April 19, 1941, the MAUD committee reported that cross-section measurements
confirmed the feasability of a fast neutron bomb. Briggs had just learned
from Lawrence that plutonium had a cross section for fast fission ten times
that of U238
In May 1941, Vannevar Bush was busy creating the Office of Scientific
Research and Development (OSRD). It's director, Bush, would report directly
to the President.
In 1942, the new element that fissioned like U235 but could be chemically
separated from uranium was called plutonium, after the Greek god of the
underworld, a god of the earth's fertility but also the god of the dead.
Whenever the US program bogged down in bureaucratic doubt, Hitler and his war
machine rescued it. On June 22, 1941, the invasion of Russia, Operation
Barborosa begin.
A push was made for a US built gaseous-diffusion plant.
It was believed that this time that a 25 pounds (lbs) of U235 would result in
an explosion equivalent to 1,800 tons of TNT.
Mark Oliphant helped goad the American program over the top. "If Congress
knew the true history of the atomic energy project,", Leo Szilard said
modestly, after the war, "I have no doubt but that it would create a special
medal to be given to meddling foreigners for distinguished services, and
Dr. Oliphant would be the first to receive one."
In March of 1941, Edward Teller swore allegiance to the United States and
became an American citizen. Fermi and Teller wondered aloud if an atomic bomb
might serve to heat a mass of deuterium sufficiently to begin thermonuclear
fusion. Such a bomb, fusing hydrogen to helium would be orders of magnitude
as energetic as a fission bomb and far cheaper in terms of equivalent explosive
force.
The first person to conceive of using a nuclear chain reaction to initiate
a thermonuclear reaction in hydrogen was Japanese physicist Tokutaro Hagiwara
of the University of Kyoto.
Roosevelt had instinctively reserved nuclear weapons policy to himself. Thus,
at the outset of the US atomic energy program, scientists were summarily
denied a voce in deciding the political and military uses of the weapons they
were proposing to build.
A scientist could choose to help or not help build nuclear weapons. That was
his only choice. The surrender of any further authority in the matter was the
price of admission to what would grow to be a separate secret state with
separate sovereignty linked to the public state throught the person and by
the sole authority of the President.
Patriotism contributed to many decisions but a deeper motive among physicists,
by the measure of their statements, was fear - fear of German triumph, fear of
a thousand year Reich made invulnerable with atomic bombs.
By September, 1941, Werner Heisenberg had learned from expeiments run by
von Weizsacker and Houtermans that a sustained chain reaction would breed
element 94 (plutonium) and he saw an open road leading to the development
of an atomic bomb.
No document Franklin Delano Roosevelt signed authenticates the fateful decision
to expedite research toward an atomic bomb. The archives divulge no smoking
gun.
On December 6, 1941, Soviet forces under General Georgi Zhukov counterattacked
across a two hundred mile front against the German army congealed in snow
and -35F cold only 30 miles outside Moscow. Hitler now discovered what a
Russian winter meant.
On December 7, 1941 at 0753, the attack on Pearl Harbor begin.
The two bombing raids accounted for 8 battleships, 3 light cruisers,
3 destroyers and four other ships sunk, capsized or damaged and 292 aircraft
damaged or wrecked, including 117 bombers. And 2,403 Americans, military and
civilians killed, 1,178 wounded in unprovoked attacks that lasted only
minutes.
With the special tools of ultramicrochemistry, the young chemists could work on
undiluted quantities of chemicals as slight as tenths of a microgram (a
dime weights about 2.5 grams or 2,500,000 micrograms). They could manage
their manipulations on the mechanical stage of a binocular stereoscopic
microscope adjusted to 30 power magnification. Fine glass capillary straws
substituted for test tubes and beakers; pipettes filled automatically by
capillary attraction; small hypodermic syringes mounted on micromanipulators
injected and removed reagents from centrifuge microcones; minature centrifuges
separated precipitated solids from liquids. The end like a fishing pole
stuck in the riverbank inside a glass housing that protected it from the
least breath of air. To weigh their Lilliputan quantities of material they
hung a weighing pan made of a snippet of platinum foil that was itself too
small to see, the the free end of the quartz fiber and measured how much
the fiber bent, a deflection which was calibrated against standard weights.
A more rugged balance developed at Berkeley had double pans suspended from
opposite ends of a quartz fiber beam strung with microscopic struts. It was
said that invisible material was being weighted with an invisible balance.
On Thursday, August 20, 1942, Glenn Seaborg announced that it was the first
time that element 94 had been beheld by the eye of man.
Edward Teller had examined two thermonuclear reactions that fuse deuterium
nuclei to heavier forms and simultaneously release binding energy. Both
required that the deteurium nuclei be hot enough when they collided, energetic
enough, violently enough in motion, to overcome the nuclear electrical
barrier that usually repels them. The minimum necessary energy was thought
at the time to be 35,000 electron volts, which corresponds to a temperature of
400 million degrees. Given that temperature, and on Earth, only an atomic
bomb might give it, both thermonuclear reactions should occur with equal
probability. In the first two deuterium nuclei collide and fuse to Helium 3,
with the ejection of a neutron and the release of 3.2 million electron volts of
energy. In the second, the same of sort of collision produces tritium,
hydrogen 3, an isotope of hydrogen with a nucleus of one proton and two
neutrons that does not occur naturally on Earth.
The D+D reactions release of 3.6 MeV was slightly less by mass than fission's
net of 170 MeV. But fusion was essentially a thermal reaction, not inherently
different in its kindling from an ordinary fire; it required no critical mass
and was therefore potentially unlimitted. Once ignited its extent depended
primarily on the volume of the fuel (deuterium) its designers supplied. And
deuterium, Harold Urey's discovery, the essential component of heavy water,
was much easier and less expensive to separate from hydrogen than U235 from
U238 and much simpler to acquire than plutonium.
Each kilogram of heavy hydrogen equaled about 85,000 tons TNT equivalent.
Theoretically 12 kilograms of liquid heavy hydrogen, 26 pounds ignited by one
atomic bomb would explode with a force equivalent to 1 million tons of TNT.
So far as Oppenheimer and his group knew at the beginning of the summer, an
equivalent fission explosion would require some 500 atomic bombs.
The arguments Bethe's and others had against a runaway explosion appear most
authoritatively in a technical history of the bomb design program prepared
under Oppenheimer's supervision immediately after the war:
It is assumed that only the most energetic of several possible (thermonuclear)
reactions would occur and that the reaction cross sections were at their
maximum values theoretically possible. Calculation led to the result that no
matter how high the temperature, energy loss would exceed energy production
by a reasonable factor. At an assumed temperature of three million electron
volts (compare with 35,000 eV known for D+D) the reaction failed to be
self-propagating by a factor of 60. This temperature exceeded the calculated
initial temperature of the deuterium reaction by a factor of 100, and that of
the fission bomb by a large factor. The impossibility of igniting the
atmosphere was thus assured by science and common sense.
To detonate 5-10 kg of heavy hydrogen liquid would require 30 kg U235.
If you use 2 or 3 tons of liquid deuterium and 30 kg U235 thsi would be
equivalent to 100,000,000 tons of TNT.
Estimated devastation area of 1000 square kilometers (360 square miles).
Radioactivity lethal over the same area for a few days.
The hydrogen bomb was thus under development in the US onward from July 1942.
On September 17, 1942, Albany born Leslie Richard Groves, age 46, deputy chief
of construction for the entire US Army, was given the command of the S-1
project, whose funding was only a week's worth of the amount of money
Groves spent in his current job. He was promoted to Brigadier General.
Groves was described as "a tremendous lone wolf".
One of the first issues the heavyweight colonel had raised with Nichols was
ore supply; was there sufficient uranium on hand? Nichols told him about a
recent and fortuitous discovery: some 1,250 tons of extraordinarily rich
pitchblende - it was 65 percent uranium oxide - that the Union Miniere had
shipped to the United States in 1940 from its Shinkolowe mine in the Belgian
Congo to remove it from German reach. Frederic Joliot and Henry Tizard had
independently warned the Belgians of the German danger in 1939. The ore was
stored in the open in two thousand steel drums at Port Richmond on Staten
Island. The Belgians had been trying to alert the US government to its
presence. On Friday, September 18, 1942, Groves sent Nichols to New York
to buy it. On Saturday, Groves approved a directive for the acquisition of
52,000 acres of land along the Clinch River in Eastern Tennesee. Site X,
the Met Lab called it.
In October, to Compton's great relief, the brigadier had convinced E.I.
du Pont de Nemours, the Delware chemical and explosives manuafacturers,
to take over building and running the plutonium production piles under
subcontract to Stone and Webster.
Meanwhile, in December, 1942, the Chicago pile contained 771,000 pounds of
graphite, 80,590 pounds of uranium oxide and 12,500 pounds of uranium metal and
cost $1 million to build. It's only moving parts were its various control
rods. On December 2, 1942, when the temperature was below zero, the first
sustained nuclear reaction was sustained at 3:53 p.m. The Chicago pile
became known as CP-1.
Oppenheimer first met General Leslie R. Groves when Groves came to Bereley
from Chicago on his initial inspection tour early in October, 1942.
Oppenheimer had discussed the need for a fast-neutron laboratory.
"We needed a central laboratory devoted wholly to the purpose where people
could talk freely with each other, where theoretical ideas and experiment
findings could affect each other, where the waste and frustration and error
of the many compartmentalized experimental studies could be eliminated,
where we could begin to come to grips with chemical, metallurgical,
engineering, and ordnance problems that had so far received no consideration.
The site chosen was a boys school called Los Alamos in New Mexico and cost
the government $440,000. The facility would be completely fenced in and
would only have one telephone. It was designated Site Y.
Robert Oppenheimer moved to Santa Fe on March 15, 1943.
Oppenheimer was already calling the bomb "the gadget", a bravado metonymy
that he termed.
Robert Serger stated that one kilogram of U235 was equivalent to 20,000 tons
of TNT. The calculations Serber reported indicated a critical mass for
metallic U235 tamped down with a thick shell of ordinary uranium of
15 kilograms: 33 pounds. For plutonium similarly tamped, the critical mass
might be 5 kilograms: 11 pounds. The heart of their atomic bomb would then
be a cantelope of U235 or an orange of Pu239 surrounded by a watermelon
of ordinary uranium tamper, the combined diameter of the two nested spheres
about 18 inches.
As a sideline because they agreed that work on the Super should continue at
second priority, they wanted to construct and operate a plant for liquifying
deuterium at -429 degrees F, the cryogenics plant was to be built near the
south rim of the mesa.
Seth Neddermeyer proposed packing a spherical layer of high explosives around a
spherical assemply of tamper and a hollow but thick-walled spherical core.
Detonated at many points simultaneously, the HE(???) would blow inward. The
shock wave from that explosion would squeeze the tamper from all sides which in
turn would squeeze the core. Squeezing the core would change its geometry
from hollow shell to solid ball. What had been subcritical because of its
geometry would be squeezed critical far faster and more efficiently than
any mere gun could fire. The gun will compress in one dimension. Two
dimensions would be better and three dimensions would be better still.
Los Alamos was Oppenheimer's high and dry secret mesa where no one had a
street address, where mail was censored, where drivers licenses went nameless,
where children would be born and families live and a few people die behind a
post office box in devotion to the cause of harnessing an obscure force of
nature to build a bomb that might end a brutal war.
On July 27th, 1943, The Hamburg firestorm was started but it peaked on July
28th. The firestorm temperature peaked at 1400 degrees F. Eight square miles
of the city were completely burned.
On November 29, 1943, modification of the first B-29 officially began.
On February 2, 1943, the Germans surrendered at Stalingrad.
The entire Oak Ridge, Tennessee facility, called the Dogpatch, was fenced off
with barb wire and public access was closed on April 1, 1943. It had 55
miles of railroad bed and 300 miles of roadbed and became home for up
to 13,000 workers.
Electromagnetic isotope separation enlarged and elaborated Francis Aston's
1918 Cavendish invention, the mass spectograph. The method depends on the
fact that an electrically charged atom travelling through a magnetic field
moves in a circle whose radius is determined by its mass.
The calutrons required 395 million troy ounces of silver (13,450 short tons)
for their magnets. This silver cost $300 million. The Y-12 complex which
did the electromagnetic isotope separation grew to 268 permanent buildings
but only produced a few micrograms of U235 per day
By August, 1943, 20,000 construction workers swarmed over the area.
At the end of 1943, Y-12 was dead in the water with less than a gram of
U235 to show for it.
Gaseous diffusion was completely novel. It was based on the theory that if
uranium gas was pumped against a porous barrier, the lighter molecules of the
gas containing U235 would pass through more rapidly than the heavier U238
molecules. The heart of the process was therefore the barrier, a porous thin
metal sheet or membrane with millions of submicrocospic openings per square
inch. These sheets were formed into tubes which were enclosed in an airtight
vessel, the diffuser. As the gas, uranium hexafluoride was pumped through
a long series, or cascade of these tubes, it tended to separate the enriched
gas moving up the cascade while the depleted moved down. However, there is
so little difference in mass between the hexafluoride of U238 and U235 that
it was impossible to gain much separation in a single diffusion step. That
was why there had to be several thousand successive stages.
Groves committed $100 million to a gaseous diffusion plant even though no
practical barrier was yet in hand.
A side product used in the gaseous diffusion plant would become known as
Teflon in later years.
The plant would hold thousands of of diffusion tanks, the largest of them of
1,000 gallon capacity, would be necessarily monumental: four stories high,
almost a half mile long in the shape of a U, a fifth of a mile wide, 42.6
acres under roof, some 2 million square feet, more than twice the total
ground area of Y-12's Alpha and Beta buildings. the gaseous-diffusion complex
was designated K-25 and the coal fired power plant to run it was ready to go
on May 31, 1943.
Twelve days after Enrico Fermi proved the chain reaction in Chicago on
December 2, 1942, Groves had assembled a list of criteria for a plutonium
production plant and had ruled out Tennessee.
The Hanford, WA site (twenty miles east of Yakima) was acquired at the end
of January of 1942 at a cost of $5.1 million and consisted of 500,000 acres or
780 square miles.
Dupont engineers were beginning to call plutonium production piles reactors
and took note that reactors should be cooled.
By August, 1943 work had begun on the water treatment plants for the three
piles, capacity sufficient to supply a city of one million people. Work gangs
begin to lay the 390 tons of structural steel, 17,400 cubic yards of concrete,
50,000 concrete blocks, and 71,000 concrete bricks that went into the pile
buildings. The B pile would begin in February, 1944.
Work on a Soviet bomb was underway in 1939. Soviet physicists realized that
the United States was pursuing a bomb program when the names of prominent
physicists, chemists, metallurgists and mathemeticians disappeared from
international journals: secrecy itself gave the secret away. The German
invasion of the USSR in June 1941 temporarily ended what had hardly just begun.
In early 194, Szilard was fighting the compartmentalization philosophy
of the army as implemented by Groves. Szilard wanted freedom of scientific
speech.
"If peace is organized before it has penetrated the public's mind that the
potentialities of atomic bombs are a reality, it will be impossible to have
peace that is based on reality. making some allowances for further development
of the atomic bomb in the next few years, this weapon will be so powerful
that there can be no peace if it is simultaneously in the possession of any
two powers unless these two powers are bound by an indissoulable politic union.
It will hardly be possible to get political action long that line unless
high efficiency atomic bombs have actually been used in this war and the fact
of their destructive power has deeply penetrated the mind of the public."
The possibility of using radioactive material bred in a nuclear reactor as a
weapon of war had been mentioned by Arthur Compton's National Academy of
Sciences committee in 1941. German development of such a weapon began
worrying the scientists at the MET lab late in 1942, on the assumption that
Germany might be a year or more ahead of the United States in pile
development. If CP-1 went critical in December, 1942, they argued, the
Germans might have had time to run a pile long enough to create fiercely
radioactive isotopes that could be mixed with dust or liquid to make
radioactive (but not fissionable) bombs. Germany might then logically attempt
preemptively to attack the MET lab, if not American cities.
At this point, a program was started up that culminated with the destruction
of the Norwegian Vemork heavy water processing plant and the last batch of
heavy water being transported to Germany.
Bohr had stated that if the atomic bomb worked, this development was going to
bring an enormous change in the situation of the world, in the whole situation
of war and the tolerability of war.
The weapon devised as an instrument of major war would end major war. It was
hardly a weapon at all, the memorandum Bohr was writing in sweltering
Washington emphasized; it was "a far deeper interference with the natural
course of events than anything ever before attempted" and it would
"completely change all future conditions of warfare." When nuclear weapons
spread to other countries, no one would be able any longer to win. A spasm
of mutual destruction would be possible. But not war.
The air-cooled pilot-scale reactor named X-10 at Oak Ridge had gone critical
at 0500 on November 4, 1943. By the summer of 1944, batches of plutonium
nitrate containing gram quantities of plutonium had begun arriving at
Los Alamos and was quickly used in over two thousand experiments.
The capture of Saipan, the largest of the Mariannas Islands had been bloody:
13,000 US casualties, 3,000 marines killed, 30,000 Japanese defenders dead.
But a more grotesque slaughter had engulfed the island's population of
civilians. Believing as propaganda had prepared them that the Americans would
visit upon them, rape, torture, castration and murder, 22,000 Japanese
civilians had made their way to the two sea cliffs, 80 and 1,000 feet high
above jagged rocks and despite appeals from Japanese speaking American
interpreters and even fellow islanders, had flung themselves, whole families
at a time to their deaths. The surf ran ran with blood; so many broken bodies
floated in the water that Navy craft overrode them to rescue. Not all the dead
had volunteered their sacrifice: many had been rallied, pushed or shot by
Japanese soldiers.
The mass suicide on Saipan, a Jonestown of its day, instructed Americans
further in the nature of the Jap. Not only soldiers but also civilians,
ordinary men, women and children chose death before surrender. On the home
islands, the Japanese were 100 million strong, and they would take a lot of
killing.
World War II would consume only 3 million tons of explosives.
The largest hydrogen bomb exploded (by the Soviets) was 60 megatons, or
60 million tons of TNT.
Married or single, the occupants of Post Office Box 1663 were young and
healthy; they produced so many babies that Groves ordered either the
reservation commander or the laboratory director to staunch the flood.
Oppenheimer had a second child, a daughter Katherine, on December 7, 1944.
Planning for a full scale test of an implosion weapon begin in March, 1944.
The first man-made nuclear explosion would be a historic event and its
designation should have a name that history might remember, Trinity.
On March 3, 1944, the first dummy atomic bomb was dropped at Muroc AFB from
a specially modified B-29 bomber.
Paul Tibbets was 29 years old and was already regarded as the best bomber
pilot at the time. His mother's name was Enola Gay Haggard, of Glidden, Iowa.
The B-29 bomber was the first pressurized bomber and could fly over 30,000 feet.
On November 24, 1944, one hundred planes from Saipan, were to bomb the Musashi
aircraft engine factory north of Tokyo. On this mission, the bomber pilots
took note that their ground speed was 450 miles per hours which was impossible
at the time and concluded that they had been caught in strongs winds blowing
at 145 miles per hour. The US Air Force had discovered the jet stream.
Washington had secretly considered sanitizing the island of Iwo Jima using
shells loaded with poison gas lobbed by ships standing well off shore.
"We shall grasp bombs, charge the enemy tanks and destroy them. With each
salvo we will without fail, kill the enemy. Each man will make it his duty
to kill ten of the enemy before dying. Slow, cruel fighting continued for
most of the month. In the end, late in March, when shell and fie had changed
the very landscape, victory had cost 6,821 marines killed, 21,865 wounded of
some 60,000 committed, a casualy ratio of 2 to 1, the highest in Marine Corps
history. Of the Japanese defenders, 20,000 had died on Iwo jima, only
1,083 allowed themselves to be captured.
On March 9, 1945, 334 B-29's took off for Tokyo loaded with more than 2000
tons of incendiaries. The Sumida River stopped the conflagration from sweeping
more than 15.8 square miles of the city. The Strategic Bombing Survey
estimates that probably more persons lost their lives by fire in Tokyo in a
6 hour period than at any [equivalent period of] time in the history of man.
The firestorm at Dresden may have killed more people but not in so short a
space of time. More than 100,000 men, women and children died in Tokyo on
the night of March 9-10, 1945; a million were injured, at least 41,000
seriously; a million in all lost their homes; Two thousands tons of
incendiaries delivered that punishment - in the modern notation, two kilotons.
But the wind, not the weight of the bombs alone, created the conflagration
and therefore the efficiency of the slaughter was in some sense still in part
an act of God.
As of January 1945 on any given day, about 85 percent of some 864 Alpha
calutron tanks operated to produce 258 grams, 9 ounces of 10 percent enriched
product. Beta tanks converted the accumulated Alpha product to 204 grams,
7.2 ounces per day of 80 percent enriched U235, sufficient enrichment to make a
bomb
Bertrand Goldschmidt, the French chemist who worked with Glenn Seaborg, puts
the Manhattan Engineering District at the height of its wartime development
with a startling comparison. It was, he writes in a memoir, "the astonishing
American creation in three years at a cost of two billion dollars, of a
formidable array of factories and laboratories - as large as the entire
automobile indistry of the United States at that date."
On April 12, 1945 at 1535, Franklin Delano Roosevelt died of a cerebral
hemmorage.
Hiroshima was the largest untouched target not on the 21st Bomber Command
priority list.
The Fat Man bomb could survive jettisoning in shallow water. Little Boy
was less forgiving because it was a gun bomb with two parts to it's critical
mass where sea water might intervene.
Kenneth T. Bainbridge was assigned the task of finding a location for the
first test. The location chosen was sixty miles northwest of Alamogordo,
New Mexico.
It was hoped that the Trinity test would be on July 4th, 1945.
On June 27, plans were made to send Little Boy (U235) to the Pacific by ship.
Two DC-3s flew out of Kirkland AFB to San Francisco to Hunter's Point Naval
Shipyard to await the sailing of the U.S.S. Indianapolis, the heavy cruiser
that would deliver the bomb to Tinian.
A wager was made on the explosive yield. Edward Teller chose 45,000 tons, TNT
equivalent, Hans Bethe chose 8,000 and Oppenheimer chose a modest 300 tons.
Groves had become irritated with Fermi.
"I had become a bit annoyed with Fermi... when he suddenly offered to take
wagers from his fellow scientists on whether or not the bomb would ignite the
atmosphere, and if so, whether it would merely destroy New Mexico or destroy
the world."
A young Harvard physicist, Donald Hornig was the last man to leave the top of
the the tower and returned to S-10000.
A series of thunderstorms rolled thru the test area and delayed the detonation
time. Groves threatened to hang the meteorologists if they would not sign
their forecasts. Groves then called the governor of New Mexico to warn him
that he might have to declare martial law. This was probably a very awkward
conversation because of the secrecy involved.
A B-29 bomber was hovering at 30,000 feet several miles away from ground zero.
Most of the scientists were rubbing suntan lotion on themselves at their
observation point, Compania Hill, 20 miles away in the darkness before dawn.
At S-10000, welders glasses (Lincoln Super-visibility Lens, Shade #10) were
being used.
Time: 05:29:45: The firing circuit closed: the X-unit discharged; the
detonators at thirty two detonation points simultaneously fired; they ignited
the outer lens shell of Composition B; the detonation waves separately bulged,
encountered inclusion of Baratol, slowed, curved, turned inside out, merged
to a common inward driving sphere; the spherical detonation wave crossed into
the second shell of solid fast Composition B and accelerated; hit the wall of
dense uranium tamper and became a shock wave and squeezed, liquefying, moving
through; hit the nickel plating of the plutonium core and squeezed, the small
sphere, shrinking, collapsing into itself, becoming an eyeball; the shock wave
reaching the tiny initiator at the center and swirling through its designed
irregularities to mix its beryllium and polonium; polonium alphas kicking
neutrons free from scant atoms of beryllium, one, two, seven, nine, hardly
more neutrons drilling into the surrounding plutonium to start the chain
reaction. Then fission multiplying its prodigious energy release through
eighty generations in millionths of a second, tens of millions of degrees,
millions of pounds of pressure. Before the radiation leaked away, conditions
within the eyeball briefly resembled the state of the universe moments before
its primordial explosion.
Then expansion, radiation leaking away. The radiant energy loosed by the chain
reaction is hot enough to take the form of soft X-rays; these leave the
physical bomb and it's physical casing, at the speed of light, far in front of
any mere explosion. Cool air is opaque to X rays and absorbs them, heating:
"the very hot air," Hans Bethe writes, "is therefore surrounded by a cooler
envelope, and only this envelope" - hot enough at that - "is visible to
observers at a distance." The central sphere of air, heated by the X rays
it absorbs, reemits lower energy X rays which are absorbed in turn at its
boundaries and reemitted beyond. By this process of downhill leapfrogging,
which is known as radiation transport, the hot sphere begins to cool itself.
When it has cooled to half a million degrees, in about one ten-thousandth of
a second - a shock wave forms that moves out faster than radiation transport
can keep up. The shock therefore separates the very hot, nearly isothermal
[i.e. uniformly heated] sphere at the center," Bethe explains. Simple
hydrodynamics describes the shock front: like a wave in water, like a sonic
boom in air. It moves on, leaving behind the isothermal sphere confined
within its shell of opacity, isolated from the outside world, growing only
slowly by radiation transport on this millisecond scale of events.
What the world sees is the shock front and it cools into visibility, the
first flash, millseconds long, of a nuclear weapon's double flash of light,
the flashes too closely spaced to distinguish with the eye. Further cooling
renders the front transparent; the world if it still has eyes to see looks
through the shock wave into the hotter interior of the fireball and
"because higher temperatures are now revealed," Bethe continues, "the total
radiation increases toward a second maximum": the second longer flash. The
isothermal sphere at the center of the expanding fireball continues opaque
and invisible, but it continues to give up its energy to the air beyond its
boundaries by radiation transport. That is, as the shock wave cools, the
air behind it heats. A cooling wave moves in reverse of the shock wave, eating
into the isothermal sphere. Instead of one simple thing, a fireball is thus
several things at once: an isothermal sphere invisible to the world; a
cooling wave moving inward toward that sphere, eating away its radiation; a
shock front propogating into undisturbed air, air that has not heard the news.
Between each of these parts lay further intervening regions of buffering air.
Eventually the cooling wave eats the isothermal sphere completely away and
the entire fireball becomes transparent to its own radiation. Now it cools
more slowly. Below the 9000 degrees F it can cool no more. Then, concludes
Bethe, "any further cooling can only be achieved by the rise of the fireball
due to its bouyancy, and the turbulent mixing associated with this rise.
This is a slow process, taking tens of seconds.
Contact with the ground was made in .65 milliseconds. At about
32 milliseconds, when the fireball had expanded to 945 feet in diameter,
there appeared immediately behind the shock wave a dark front of absorbing
matter, which travelled slowly out until it became invisible at 0.85 s
[the expanding front about 2,500 feet across]. The shock wave became
invisible at about 0.10 s.
At 0836 that morning, four hours after the light flung from the Jornada del
Muerto blanched the face of the moon, the Indianapolis sailed with its cargo
under the Golden Gate and out to sea.
Tinian is a miracle. Here, 6,000 miles from San Francisco, the United States
armed forces have built the largest airport in the world. A great coral ridge
was half leveled to fill a rough plain, and to build six runways, each an
excellent 10 lane highway, each almost two miles long. Besides these runways
stood in long rows, the great silvery airplanes. They were not there by the
dozens but by the hundreds. From the air this island, smaller than Manhattan,
looked like a giant aircraft carrier, its deck loaded with bombers.
Stimson remarked to Harvey Bundy, with relief, "I have been responsible for
spending two billion dollars on this atomic venture. Now that it is successful
I shall not be sent to prison in Fort Leavenworth."
On August 6, 1945, at 0227, Paul Tibbets started up the Enola Gay's engines.
At 0751, at 31,000 feet, they achieved landfall at 328 miles per hour. A few
minutes later the four ton payload was dropped. At 08:16:02, 43 seconds after
it left the Enola Gay, 1,900 feet above the courtyard of the Shima Hospital,
Little Boy detonated with an estinated force of 18 kilotons.
The world of the dead is a different place than the world of the living.
In Hiroshima, the two worlds converged.
By 2200, August 8, 1945, Fat Man was loaded onto a B-29 named Bock's Car, named
after it's commander Frederick Bock. Bock's Car left Timian at 0347 and
Fat Man exploded 1,650 feet over Nagasaki at 1102 with an estimated force of
22 kilotons.
On August 10, the Japanese send out the white flag through Switzerland.
The third bomb was to be sent to Timian on August 12 and be ready for delivery
by August 17th.
The Japanese emperor wrote:
"Despite the best that has been done by everyone... the war situation has
developed not necessarily to Japan's advantage while the general trends of the
world have all turned against her interest. Moreover, the enemy has begun to
employ a new and most cruel bomb, the power of which to do damage is indeed
incalculable, taking the toll of many innocent lives... This is the reason
why We have ordered the acceptance of the provisions of the Joint declaration
of the Powers....
The hardships and suffererings to which Our nation is to be subjected hereafter
will be certainly great. We are keenly aware of the inmost feelings of all ye
Our subjects. However it is according to the dictate of time and fate that We
have resolved to pave the way for a grand peace for all generations to come by
enduring the unendurable and suffering what is unsufferable...
Let the entire nation continue as one family from generation to generation...."
The experience of Hiroshima and Nagasaki was the opening chapter to the
possible annihilation of mankind.
The US government published a detailed report on the scientific aspects
of the atomic bomb development with Groves approvement.
H. G. Wells lived to know of Hiroshima and Nagasaki. Deeply pessimistic in
his final years, he died at eighty on August 13, 1946.
The Super conference examined only one design for a thermonuclear weapon, the
design Teller and his group had developed during the war, the so-called
classical Super, with an estimated explosive force of 10 megatons. The
ingredients for the classical Super would be an atomic bomb, a cubic meter of
liquid deuterium and an indefinite amount of the rare isotope of hydrogen,
tritium, which because of it's short 12.26-year half life does not normally
exist in nature but can be created in a nuclear reactor by bombarding
lithium with neutrons. How those components would have been arranged in the
classical Super is still secret: probably spherically, the fission trigger
and hydrogen isotopes physically contiguous and contained a heavy tamper.
In June 1946, three months after the Super conference, the US nuclear weapons
stockpile consisted of nine Fat Man bombs, of which no more than seven could
be made operational for lack of initiators. The stockpile held only thirteen
bombs a year later, two years after the end of the war. Plutonium production
was the crucial bottleneck. The high neutron flux of he Hanford production
piles had proven damaging.
On September 23, 1949, the Soviets exploded their first atomic bomb.
Stanislaw Ulam realized that if the thermonuclear materials were physically
seperated from the fission primary, the enormous flux of X rays coming off
the primary might be applied somehow to start the thermonuclear burning in
the fraction of a second before the slower shock wave caught up and blew
everything apart.
The X rays from the primary might heat the thermonuclear secondary directly
(as microwaves heat food in a microwave oven)) but they could not squeeze it
efficiently to the greater density that would promote fusion. Some other
material would need to intervene. It turned out that ordinary plastic would
serve. Dump so large a flux of X rays into a layer of plastic foam wrapped
around a cylindrical stick of thermonuclear materials and the plastic would
heat instantaneously to a plasma - a hot ionized gas - expanding explosively
at pressures thousands of times more intense than the pressures high explosives
can generate. So a fission primary - a little Fat Man, no larger in today's
efficient weapons than a soccer ball - might occupy one end of an evacuated
cylindrical casing. Farther along the casing, a layer of plastic might wrap
a cylindrical arrangement of thermonuclear material. Fire the primary and the
X ray flux would radiate the plastic at the speed of light faster than the
expanding fission shock wave coming up from behind. Configuring the plastic
would be much simpler than configuring the high explosive lenses; the
light-swift X rays would irradiate it simultaneously along its entire length
and the resulting implosion would be beautifully symmetrical.
The second half of the new concept was probably a further nesting of cylinders
within cylinders: an outer casing of U238 to scatter X rays from the primary
into the plastic; a layer next of plastic; a layer next of U238 tamper; a layer
next of thermonuclear materials; and at the axis of the cylinder a stick of
plutonium. It would also start a second fission chain reaction in the stick of
plutonium by squeezing it to critical mass. That would add a further flux
of heat and pressure to the thermonuclear materials and push the fusion
reaction over the top. The U238 later, in turn would benefit from the dense
flux of neutrons released in thermonuclear burning and would fission above the
1 MeV U238 fission threshhold. Neutrons from that fission would then
contribute to preparing the thermonuclear materials for further burning.
Such a design is usually described as fission-fusion-fission.
On November 1, 1952, the Mike shot on the small island of Elugelab weighted
65 tons and yielded 10.4 megatons. The fireball expanded to 3 miles and the
explosion generated a crater half a mile deep and two miles wide.
Mike was fueled with liquid deuterium and tritium for simplicity of measuring.
For a deliverable bomb, the thermonuclear material of choice would be lithium
deuterium, a stable powder, the lithium in the form of the isotope Li6, which
constitutes 7.4 percent of natural lithium but can be separated from it
relatively easily. Neutrons from the fission components of a lithium fueled
bomb would produce tritium almost instantly from Li6 which would then fuse with
the deuteride to develop the thermonuclear burning just as the wet and bulky
liquid hydrogen isotopes had done in Mike. The dry design was tested in the
spring of 1954 in Operation Castle.
The Castle Bravo test was a device using LiD as its fuel and yielding
15 megatons. It was the first hydrogen bomb small enough to be delivered
by plane.
A true Soviet thermonuclear, dropped from an aircraft in test, followed on
November 23, 1955.
----------------------------------------------------------------------------
Simon and Peierls settled on ordinary gaseous diffusion (as opposed to
gaseous thermal diffusion as the best method for isotope separation.
Gases diffuse through porous materials at rates that are determined by their
molecular weight, lighter gases diffusing faster than heavy gases. In the
case of uranium hexafluoride, the enrichment factor would be slight, 1.0043
under ideal circumstances. But with enough repetitions of the process, any
degree of enrichment was possible.
The Battle of Britain began in mid-August in 1940. By November, 13,700 tons
of high explosives had fallen and 12,600 tons of incendiary cannisters, an
average of 201 tons per night; for the entire Blitz, September to May, the
total tonnage reached 18,800 - 18.8 kilotons, spread across nine months.
London civilian deaths in 1940 and 1941 totaled 20,083. Only 42 civilians
lost their lives in 1942.
The first separation of U-235 and U-238 was accomplished on
February 28 and 29, 1940 and the sample was sent to Columbia University.
Oak Ridge Alpha I calutron racetrack for the electromagnetic separation of
U235.
The K-25 gaseous diffusion plant in Oak Ridge, Tennessee was half a mile long
and covered 42.6 acres under roof.
The plutonium production complex off the Columbia River at Hanford, Washington.
Oak Ridge Uranium Processing Plant
http://maps.google.com/maps?f=q&hl=en&geocode=&q=Oak+Ridge,+TN&ie=UTF8&ll=35.934131,-84.39311&spn=0.016401,0.021372&t=h&z=16&om=1
Hanford, WA Nuclear Reservation
http://maps.google.com/maps?f=q&hl=en&geocode=&q=Hanford,+WA&ie=UTF8&ll=46.556618,-119.532795&spn=0.055715,0.085487&t=h&z=14&om=1
Los Alamos, NM
http://maps.google.com/maps?f=q&hl=en&geocode=&q=Los+Alamos,+NM&ie=UTF8&ll=35.870777,-106.320877&spn=0.016414,0.021372&t=h&z=16&om=1
Alamogordo, NM
http://maps.google.com/maps?f=q&hl=en&geocode=&q=Alamogordo,+NM&ie=UTF8&ll=33.014421,-106.211014&spn=0.543531,0.683899&t=h&z=11&om=1
http://www.radiochemistry.org/history/nuke_tests/trinity/index.html
Ivan The Terrible
http://en.wikipedia.org/wiki/Tsar_Bomba
Castle Bravo
http://en.wikipedia.org/wiki/Castle_Bravo
Atomic craters near Las Vegas
http://maps.google.com/?ie=UTF8&t=h&om=0&ll=37.158264,-116.05854&spn=0.047404,0.089951&z=14
obergruppenfuhrer, Schultzstaffel (SS)
In the 1960s and 1970s, theoretical physicists developed a standard model
of high energy physics, which predicted what kind of particles come
together to form electrons, protons and neutrons. Since then, 12 major
subatomic particles have been discovered: six uncharged particles called
leptons and six charged particles called quarks. Physicists have also
identified five particles that carry force, known as bosons. The evasive
Higgs boson is the only one that has yet to be observed.
|