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Trinity test

2007 Schools Wikipedia Selection. Related subjects: Military History and War

                          "Trinity" test site
   An early stage in the "Trinity" fireball, photographed by Berlyn
   Brixner
     Type   Nuclear test site
   Location 33.675° N 106.475° W near  Alamogordo
   Operator Manhattan Engineering District ( USA)
    Status  Inactive
    In use  July 16, 1945
   Trinity test site
   United States Locator Map
   Map showing location of the site

   The "Trinity" test was the first test of a nuclear weapon, conducted by
   the United States on July 16, 1945 at 33.675° N 106.475° W, thirty
   miles (48 km) southeast of Socorro on what is now White Sands Missile
   Range, headquartered near Alamogordo, New Mexico. It was a test of an
   implosion-design plutonium bomb, the same type of weapon later dropped
   on Nagasaki, Japan. The detonation was equivalent to the explosion of
   around 20 kilotons of TNT, and is usually credited as the beginning of
   the Atomic Age.

History

   The creation of nuclear weapons arose out of political and scientific
   developments of the late 1930s. The rise of fascist governments in
   Europe and new discoveries about the nature of atoms converged in the
   plans of the United States and the United Kingdom to develop powerful
   weapons using nuclear fission as their primary source of energy. The
   Manhattan Project, as the Allied effort was called, culminated in the
   test of a nuclear weapon at what is now called Trinity site in July
   1945, and the atomic bombings of Hiroshima and Nagasaki a few weeks
   later.

Development

   While U.S. and British efforts to investigate the feasibility of
   nuclear weapons began as early as 1939, the effort at development only
   began in earnest in 1942 when it was transferred under the authority of
   the U.S. Army and became the Manhattan Project. The project focused on
   the development of fissile material to power the nuclear chain
   reactions which took place inside the weapons, and the design of the
   weapons themselves at the top-secret Los Alamos Laboratory in New
   Mexico.
   The two types of fission bomb assembly methods investigated during the
   Manhattan Project. Because of the complexity of the implosion design,
   it was deemed that it needed to be tested before use in combat.
   Enlarge
   The two types of fission bomb assembly methods investigated during the
   Manhattan Project. Because of the complexity of the implosion design,
   it was deemed that it needed to be tested before use in combat.

   From January 1944 to July 1945, the large-scale production plants were
   set in operation, and the fissile material thus produced was then used
   to determine the features of the weapons. Multipronged research was
   undertaken to follow several angles of attack against the problem of
   bomb design. Early decisions about weapon design had been based on
   minute quantities of uranium-235 ( enriched uranium) and plutonium
   created in pilot plants and laboratory cyclotrons. From these results
   it was thought that the creation of a bomb was as simple as shooting
   one piece of fissile material into another to form a critical mass.

   The production of uranium-235 proved to be quite difficult with
   existing technology, but the production of plutonium was comparatively
   easier, as it was a by-product of specially constructed nuclear
   reactors, the first of which was developed by Enrico Fermi only in
   1942. Reactor-grade plutonium, however, was considerably less pure than
   cyclotron-produced plutonium, and the presence of another isotope of
   plutonium in the resulting product meant that the simple "gun type"
   model of bomb design would not work: the presence of extra neutrons
   meant that the weapon would pre-detonate with a greatly reduced yield.
   This problem, when discovered in 1942, led to a redesign of the
   plutonium bomb towards the idea of "implosion", by which a spherical
   core of plutonium would be compressed using conventional explosives,
   which would increase its density and thus create a critical mass.

   The problem was then to construct a weapon which would precisely
   compress the plutonium sphere on all sides exactly equally—any error
   would result in a "fizzle" which would simply eject the valuable
   plutonium and not result in a large explosion. Because of the
   difficulties in creating the explosive lenses for perfect compression
   using the existing technology, it was decided by Manhattan Project
   military leader General Leslie Groves and scientific director J. Robert
   Oppenheimer that a test of the concept would have to be undertaken
   before a weapon could be confidently used in war conditions.

Test planning

   Planning for the test itself was assigned to Kenneth Bainbridge, a
   professor of physics at Harvard University, working under explosives
   expert George Kistiakowsky. A proper site had to be located that would
   guarantee secrecy of the project's goals even as it planned to detonate
   a nuclear weapon of unknown strength, proper scientific equipment had
   to be assembled for retrieving data from the test itself, and safety
   guidelines had to be developed to protect project personnel from the
   results of an unknown and highly dangerous experiment. Official test
   photographer Berlyn Brixner set up dozens of cameras to capture the
   event on film.

Test site

   Trinity Site (red arrow) near Carrizozo Malpais
   Enlarge
   Trinity Site (red arrow) near Carrizozo Malpais

   The site was part of the Alamogordo Bombing Range, now the White Sands
   Missile Range. The test site is at the northern end of the range,
   between the towns of Carrizozo and Socorro, New Mexico, in the Jornada
   del Muerto in the southwestern United States ( 33.675° N 106.475° W).

Name

   The exact origin of the name is unknown, but it is often attributed to
   laboratory leader J. Robert Oppenheimer as a reference to the poetry of
   John Donne. Oppenheimer had been exposed to Donne primarily through his
   former girlfriend Jean Tatlock, who had committed suicide in July 1944.
   In 1962, General Leslie Groves wrote to Oppenheimer on the origin of
   the name, asking if he had chosen it on the basis that it was a name
   common to rivers and peaks in the West and would not attract attention.
   "I did suggest it, but not on [that] ground... Why I chose the name is
   not clear, but I know what thoughts were in my mind. There is a poem of
   John Donne, written just before his death, which I know and love. From
   it a quotation: 'As West and East / In all flatt Maps—and I am one—are
   on, / So death doth touch the Resurrection.'" ("Hymn to God My God, in
   My Sicknesses"). Oppenheimer continued, "That still does not make a
   Trinity, but in another, better known devotional poem Donne opens,
   'Batter my heart, three person'd God;—.' Beyond this, I have no clues
   whatever." (Holy Sonnets XIV).

Test predictions

   The explosives of the Gadget were raised up to the top of the tower for
   the final assembly.
   Enlarge
   The explosives of the Gadget were raised up to the top of the tower for
   the final assembly.

   Betting pools were set up among the observers for the results of the
   test. Some predictions ranged from zero, a dud, to 18 kilotons of TNT
   (predicted by I. I. Rabi), to destruction of the state of New Mexico,
   to ignition of the atmosphere and incineration of the planet
   (fortunately, this result was calculated to be almost impossible
   beforehand, though for a while it caused some of the scientists some
   anxiety). As it turned out, Rabi won the bet.

Test preparation

   There was a pretest explosion of 108 tons of TNT on May 7 to calibrate
   the instrumentation. (Since then, nuclear detonation yields have been
   measured in units of tons of TNT equivalent, or the equivalent of that
   many tons of TNT.) For the actual test, the plutonium-core nuclear
   weapon, nicknamed the gadget, was hoisted on the top of a 20-meter
   steel tower for detonation — the height would give a better indication
   of what the weapon would be like when dropped from an airplane, as
   detonation in the air would maximize the amount of energy applied
   directly to the target (as it expanded in a spherical shape), and would
   kick up the least nuclear fallout.
   The "gadget", fully assembled and ready to test.
   Enlarge
   The "gadget", fully assembled and ready to test.

   The " gadget" was assembled at the nearby McDonald Ranch House, the
   components arriving on July 12. It was assembled on the 13th and
   precariously winched up the tower the following day. In case of
   failure, a huge steel canister code-named "Jumbo" was prepared to
   recover the valuable plutonium at the order of General Groves. Weighing
   240 tons, "Jumbo" was meant to contain the explosion from the 5 tons of
   conventional explosives used to compress the plutonium in case the
   chain reaction failed. At great expense, "Jumbo" was constructed in
   Pittsburgh, Pennsylvania, and brought out to the test site by rail, but
   by the time it arrived the confidence of the scientists was high enough
   that they decided not to use it. It was instead hoisted up in a steel
   tower 800 yards (730 m) from the "gadget", as a rough measure of how
   powerful it would be. In the end, "Jumbo" survived, though its tower
   did not.

   The detonation was initially planned for 4:00 a.m. but was postponed
   due to rain and lightning from early that morning. Under conditions of
   rain it was feared that the danger from radiation and fallout would be
   greatly increased, and the lightning put the scientists on edge about
   the possibility of an accidental detonation.

The explosion

   One of the few color photographs of the "Trinity" explosion.
   Enlarge
   One of the few colour photographs of the "Trinity" explosion.

   At 4:45 a.m. a crucial weather report came in favorably, and at 5:10
   a.m. the twenty-minute countdown began. Most of the top-level
   scientists and military officers were observing from a base camp, ten
   miles (16 km) southwest of the test tower. Many other observers were
   around twenty miles (32 km) away, and some others were scattered at
   different distances, some in more informal situations (physicist
   Richard Feynman claimed to be the only person to see the explosion
   without the dark glasses provided, relying on a truck windshield to
   screen out harmful ultraviolet wavelengths). The final countdown was
   read by physicist Samuel K. Allison.

   At 05:29:45 local time ( Mountain War Time), the device exploded with
   an energy equivalent to around 19 kilotons of TNT (87.5 TJ). It left a
   crater of radioactive glass in the desert 3 meters (10 feet) deep and
   330 meters (1,100 feet) wide. At the time of detonation, the
   surrounding mountains were illuminated brighter than daytime for one to
   two seconds, and the heat was reported as being as hot as an oven at
   the base camp. The observed colors of the illumination ranged from
   purple, to green, and eventually to white. The roar of the shock wave
   took 40 seconds to reach the observers. The shock wave was felt over
   160 km (100 miles) away, and the mushroom cloud reached 12 km (7.5
   miles). As Los Alamos director J. Robert Oppenheimer watched the
   demonstration, he later said that a line from the Hindu scripture the
   Bhagavad Gita came to mind:

                I am become Death, the destroyer of worlds.

   Test director Kenneth Bainbridge replied to Oppenheimer, "Now we are
   all sons of bitches." According to Oppenheimer's brother, Frank, at the
   time of the test Robert simply said, "It worked."
   Ground zero after the test.
   Enlarge
   Ground zero after the test.

   News reports quoted a forest ranger 150 miles (240 km) west of the site
   as saying he saw "a flash of fire followed by an explosion and black
   smoke." A New Mexican 150 miles (240 km) north said, "The explosion
   lighted up the sky like the sun." Other reports remarked that windows
   were rattled up to 200 miles (320 km) away and the sound of the
   explosion could be heard at just as great a distance.
   An aerial shot of the "Trinity" crater shortly after the test. The
   small crater in the southeast corner was from the earlier test
   explosion of 100 tons of TNT.
   Enlarge
   An aerial shot of the "Trinity" crater shortly after the test. The
   small crater in the southeast corner was from the earlier test
   explosion of 100 tons of TNT.

   In the crater the desert sand, which is largely made of silica, melted
   and became glass of a light green colour and mildly radioactive; this
   was named Trinitite. The crater was filled in soon after the test.

   The Alamagordo Air Base issued a 50-word press release noting "an
   explosion of a remotely located ammunitions dump, in which no one had
   been killed or injured." The actual cause was not publicly acknowledged
   until after the August 6 attack on Hiroshima.

   The Manhattan Project's official journalist, William L. Laurence, had
   previously put multiple press releases on file with his office at the
   New York Times to be released in case of an emergency, ranging from a
   successful test (the one which was used) to more macabre scenarios
   explaining why all of the scientists had perished in a single freak
   accident.

   Around 260 personnel were present, none closer than 9 km. At the next
   test series, Operation Crossroads in 1946, over 40,000 people were
   present.

Test results

   Fallout around the Trinity site. The radioactive cloud moved towards
   northeast with high radiation levels within about 100 miles (161 km).
   Enlarge
   Fallout around the Trinity site. The radioactive cloud moved towards
   northeast with high radiation levels within about 100 miles (161 km).

   The results of the test were conveyed to President Harry S. Truman and
   were used by him as leverage in his negotiations with the Soviet Union
   at the Potsdam Conference. Truman was, however, somewhat shocked by
   Joseph Stalin's lack of response when he told him in private about the
   weapon; Stalin was already well aware of the American endeavor —
   through espionage.

   Following the success of the Trinity test, two bombs were prepared for
   use against Japan. The first, dropped on Hiroshima, Japan, on August 6,
   was code-named " Little Boy", and used uranium-235 as its fission
   source. It was an untested model, but seemed very likely to work and
   was considerably more simplistic in design than the implosion model; in
   any event, it could not be tested as there was only enough uranium-235
   for one bomb. The second bomb, dropped on Nagasaki, Japan, on August 9,
   was code-named " Fat Man", and was a plutonium bomb of the type tested
   at the Trinity test. The atomic bombings of Hiroshima and Nagasaki
   killed at least 120,000 people outright and many more over time, but
   were alleged by many internationally credible sources to have saved
   many more lives in the long run. (See Atomic bombings of Hiroshima and
   Nagasaki for information on this historical question and the
   controversy that surrounds it.)
   Gen. Leslie R. Groves and others at remains of the Trinity shot tower a
   few weeks later.
   Enlarge
   Gen. Leslie R. Groves and others at remains of the Trinity shot tower a
   few weeks later.

   The information about the Trinity test was made public shortly after
   the bombing of Hiroshima. The Smyth Report, released on August 12,
   1945, gave some information on the blast, and the hardbound edition
   released by Princeton University Press a few weeks later contained the
   famous "bulbous" pictures of the Trinity fireball.

   Oppenheimer and Groves posed for reporters near the remains of the
   mangled test tower shortly after the war. In the years after the test,
   the pictures have become a potent symbol of the beginning of the
   so-called " atomic age", and the test has often been featured in
   popular culture.

The site today

   An obelisk now stands at what was originally the "Trinity" target
   point.
   Enlarge
   An obelisk now stands at what was originally the "Trinity" target
   point.

   In 1952 the site of the explosion was bull-dozed and the remaining
   trinitite was disposed of. On December 21, 1965, Trinity Site was
   declared a National Historic Landmark district, and was
   administratively listed on the National Register of Historic Places on
   October 15, 1966.

   More than fifty years after the test, there is still a little residual
   radiation at the site, about ten times higher than normal. Officials
   maintain that the amount of exposure received during a one-hour visit
   is far less than that received from eating food and being exposed to
   the sun. The Trinity monument, a rough-sided, lava rock obelisk around
   12 ft (3.65 m) high, marks the explosion's hypocenter, and "Jumbo" is
   still kept nearby.

   The site is still a reasonably popular destination for those interested
   in atomic tourism, though it is only open to the public twice a year,
   on the first Saturdays of April and October. On July 16, 2005, a
   special tour of the site was conducted to mark the 60th anniversary of
   the Trinity test and hundreds (some news sources reported thousands) of
   visitors arrived to commemorate the occasion.

   Retrieved from " http://en.wikipedia.org/wiki/Trinity_test"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
