Los Alamos

Engineering places: Los Alamos

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In celebration of IET@150, we look at feats of engineering from around the world.

Great engineering laboratories are usually in easy-to-get-to places; that is, unless you’re keen that no-one knows what it is you’re engineering.

It was this idea that brought Robert Oppenheimer to a private ranch school for boys known as ‘Los Alamos’. Los Alamos was certainly ‘out of the way’ – perched on the Pajarito plateau in north central New Mexico – but more than that, it was near where Oppenheimer had a ranch. He felt the spectacular mountain views would prove inspirational to the physicists and engineers he would bring there to work on the Manhattan project.

Less than six months later, the ranch and surrounding 54,000 acres were military property and the first army commander arrived. The main site was to be the old ranch, which included 27 houses and various workshops. Oppenheimer modestly budgeted $100,000, but in doing so, proved he was more of a scientist than a quantity surveyor. By November 1943, the costs had topped $7m.

By Christmas 1943, there were several hundred scientists and engineers on site and a total population, including families, of 3,500. This would later rise to over 10,000. With such a large population the meagre resources of the ranch were in high demand, none more so than the old faculty accommodation of the ranch school, whose six log and stone cabins became known as ‘bathtub row’ due to their ‘luxurious’ plumbing facilities. For the rest of the team, various prefabricated ‘cities’ rose from the mesa, all of which would groan under the strain the burgeoning settlement put on electricity and water supplies.

Early development focused on a gun-type fission weapon using plutonium, known as ‘Thin Man’ after a Dashiell Hammett novel. However, concerns raised in 1942 by British physicist James Chadwick that such a weapon might undergo a ‘pre-detonation’ while being assembled proved well-founded and the system had to be abandoned.

Fortunately, a separate ‘implosion’ device was being developed in which sub-critical masses of fissile material were driven together by a series of conventional detonations to form a critical mass. This ‘Fat Man’ design, named after a character in ‘The Maltese Falcon’, now became a priority.

Due to the complexity, it was decided that a full test was imperative and the first Trinity test at Alamogordo bombing range in New Mexico was scheduled. At 5.40am on 16 July 1945, the ‘gadget’ was initiated, with a yield equivalent to 20 kilotonnes of TNT. With the shockwave felt over 100 miles away, it became necessary to spread a story that an ammunition dump at Almogordo had accidentally exploded.

Work on a gun-type uranium weapon also continued with the ‘Little Boy’ design, named after another ‘The Maltese Falcon’ character, in case Fat Man proved unworkable. Early tests at Los Alamos were so successful that the project commander ordered Oppenheimer to concentrate on this, with a deadline of having a useable weapon by 1 July 1945.

Due to the simpler nature of the system, it was decided that a full test was not required and instead a series of test firings of the conventional parts of the weapon and test drops of the whole device, without the fissile material, were undertaken.

Los Alamos now had the data required for construction of the final weapons and a date of 1 August 1945 was set for the delivery of a working Little Boy device, with a Fat Man implosion device to follow shortly after.

By 31 July, the first complete Little Boy device was ready and the attack order was issued – the strikes were to occur on or after 3 August as weather allowed.

Five members of the Los Alamos team flew on the Hiroshima mission. The next day, they met on Guam and agreed that a Fat Man device could be delivered by 9 August. Three bomb pre-assemblies were delivered from Los Alamos to Tinian Island, and after a ‘dress rehearsal’ on 8 August, Nagasaki was bombed at 11.01am the next day. Between 130,000 and 230,000 people died in the two attacks.

After the surrender of Japan on 14 August, Oppenheimer resigned as director of Los Alamos, leaving on 17 October that year, his famous quote from the Bhagavad Gita on watching the Trinity test perhaps ringing in his ears: “Now I am become Death, the destroyer of worlds.”

The work of Los Alamos was far from over, however, and his successor, Norris Bradbury, had ambitious plans for a new laboratory site with more salubrious accommodation. But most scientists at the site were keen to return now to their homes and universities and escape the isolation of the New Mexico desert. The remaining team, charged with preparing devices for the upcoming US atomic tests in the Pacific, codenamed Crossroads, were split over several sites and the Los Alamos population dropped to under 1,000.

On 1 January 1947, the name officially changed to the Los Alamos Scientific Laboratory and slowly the prefabricated buildings were replaced with a more permanent base, where the work was expanded to include particle accelerator engineering and nuclear medicine. Even the post-war period was not without tragedies however, and the plutonium research pit known later as ‘the demon core’ took the lives of two physicists in experimental accidents.

Nor did it prove that the remote site had been quite as secure as hoped. In January 1950, theoretical physicist Klaus Fuchs, who had worked at Los Alamos from August 1944, confessed to being a Soviet spy and was sentenced to 14 years imprisonment by a British court. He served nine years before emigrating to East Germany.

In 1965 several decaying buildings associated with the Manhattan project were declared National Historic Landmarks, but the large part of Los Alamos remained a functioning laboratory as it does today. The site’s work now is said to include development of biofuels, cell-sorting technologies, disease detection and monitoring, and medical scanner technology. However, much of its output remains classified.

Timeline: Los Alamos

July 1941: The MAUD committee in Britain concludes that an atomic bomb is feasible.

21 October 1941: Robert Oppenheimer is brought in to check the physics of the MAUD committee report.

8 October 1942: Oppenheimer suggests using a separate bomb design laboratory.

1 April 1943: Los Alamos officially becomes military establishment.

April-May 1943: Development concentrates on a gun-type fission weapon using plutonium.

30 November 1943: Population of Los Alamos reaches 3,500.

March 1944: Kenneth Bainbridge (Harvard professor of physics) plans the initial nuclear test.

April 1944: The lab looks at an alternative design called Fat Man. Little Boy also developed.

December 1944: Test firing for Little Boy is done full-scale on the gun design at the Anchor Ranch.

May 1945: The first Fat Man bomb is ready – except for the uranium payload.

15 June 1945: The uranium-235 projectile is ready for Little Boy.

16 July 1945: The first Nuclear Test takes place.

25 July 1945: The acting Chief of Staff of the US Army, General Thomas T Hardy, signs off the bombing plan.

6 August 1945: B-29 bomber Enola Gay drops a Little Boy on Hiroshima.

9 August 1945: The B-29 Bockscar drops a Fat Man on Nagasaki.

21 August 1945: Harry Daghlian suffers fatal radiation poisoning after accidentally dropping a tungsten carbide brick onto a sphere of plutonium.

November 1945: Oppenheimer steps down as director.

1 January 1947: Name is officially changed to the Los Alamos Scientific Laboratory.

January 1950: Klaus Fuchs, who had worked at Los Alamos from August 1944, confesses to being a spy and is sentenced to 14 years imprisonment by a British Court.

1952/1953: Atomic Energy Commission creates the Lawrence Livermore National Laboratory as a competitor to Los Alamos.

1965: Several buildings associated with the Manhattan Project are declared a National Historic Landmark.

1981: The site officially becomes Los Alamos National Laboratory.

See more about the IET@150 at theiet.org/about/iet-150-anniversary/

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