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Authors: Jim Baggott
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that involved not science but principles of action in the face of the approaching war’, he later wrote.
Szilard could also be intensely irritating, and Fermi now lost his temper. He thought Szilard’s zeal for secrecy absurd, but eventually relented under pressure. The results were not published.
Super-cyclotron
Ernest Lawrence was a visionary. The inventor of the cyclotron was a rather atypical physicist. A blond, blue-eyed Midwesterner of Norwegian parentage, he carried the values of his Lutheran upbringing into adulthood, and into his science. His preference for smart suits and his magisterial manner lent him an appearance that was more businessman than scientist. And, in truth, managing the kind of scientific enterprise that he was keen to establish at Berkeley’s Radiation Laboratory – or ‘Rad Lab’ – demanded a much more businesslike approach. His teenage experiences as a kitchenware salesman had given him the necessary selling skills, and had taught him the rudiments of fund-raising.
Lawrence had invented the cyclotron in 1929. Use a magnet to confine a stream of protons to move in a circle while accelerating them to higher and higher speeds using an alternating electric field and, Lawrence had figured, you had a machine for penetrating the secrets of the atomic nucleus. He built a small demonstration model for just $25. It was four inches in diameter and covered in red sealing wax. Although it didn’t quite deliver the proton energies that Lawrence claimed it should, it was enough to impress his scientific colleagues and prove the principle. However, the machine’s scientific name, the magnetic resonance accelerator , was too abstract and clumsy. Cyclotron sounded much more futuristic, and therefore much more appealing to potential sponsors.
He was already thinking on a larger scale, and there quickly followed a succession of such machines. A cyclotron containing a magnet with an eleven-inch diameter pole face delivered proton energies of over a million electron volts. This was followed by a 27-inch machine, which then quickly became a 37-inch cyclotron. When news of the discovery of nuclear fission in uranium reached Berkeley in January 1939, Lawrence was planninga 60-inch cyclotron that would deliver proton energies of the order of 20 million electron volts. It would need a magnet weighing 200 tons.
The 60-inch machine was barely operational at the Rad Lab’s Crocker Laboratory before Lawrence was busy designing the next one. This was to be a gargantuan 120-inch super-cyclotron with a magnet weighing 2,000 tons. Lawrence estimated that this would deliver proton energies of 100 million electron volts, on the threshold of nuclear-scale energies. Lawrence approached the Rockefeller Foundation with requests for support. His pitch was greatly strengthened when, in the middle of a game at the Berkeley Tennis Club on 9 November, he was informed that he had just won the 1939 Nobel prize for physics.
Suitably emboldened, as Christmas approached Lawrence escalated the scale of the super-cyclotron even further, to include a magnet with 184inch pole faces (the largest diameter of commercially-available steel plate), weighing 5,000 tons. It would cost an estimated $1.5 million to build.
The outbreak of war in Europe in September had an immediate personal impact on Lawrence – after several days of anxious waiting he heard that his brother John had survived the sinking of the Athenia by a German submarine on 2 September. But life at the Rad Lab continued pretty much as normal. There were interesting experiments to be performed on uranium using the 60-inch cyclotron, but this was work that would have been carried out irrespective of the war. There was no sense yet that the Rad Lab was in any way involved in ‘war work’.
A photograph from around this time shows the Rad Lab faculty, gathered in three rows beneath the magnet of the 60-inch cyclotron. Lawrence is sitting in the centre of the front row.
Szilard could also be intensely irritating, and Fermi now lost his temper. He thought Szilard’s zeal for secrecy absurd, but eventually relented under pressure. The results were not published.
Super-cyclotron
Ernest Lawrence was a visionary. The inventor of the cyclotron was a rather atypical physicist. A blond, blue-eyed Midwesterner of Norwegian parentage, he carried the values of his Lutheran upbringing into adulthood, and into his science. His preference for smart suits and his magisterial manner lent him an appearance that was more businessman than scientist. And, in truth, managing the kind of scientific enterprise that he was keen to establish at Berkeley’s Radiation Laboratory – or ‘Rad Lab’ – demanded a much more businesslike approach. His teenage experiences as a kitchenware salesman had given him the necessary selling skills, and had taught him the rudiments of fund-raising.
Lawrence had invented the cyclotron in 1929. Use a magnet to confine a stream of protons to move in a circle while accelerating them to higher and higher speeds using an alternating electric field and, Lawrence had figured, you had a machine for penetrating the secrets of the atomic nucleus. He built a small demonstration model for just $25. It was four inches in diameter and covered in red sealing wax. Although it didn’t quite deliver the proton energies that Lawrence claimed it should, it was enough to impress his scientific colleagues and prove the principle. However, the machine’s scientific name, the magnetic resonance accelerator , was too abstract and clumsy. Cyclotron sounded much more futuristic, and therefore much more appealing to potential sponsors.
He was already thinking on a larger scale, and there quickly followed a succession of such machines. A cyclotron containing a magnet with an eleven-inch diameter pole face delivered proton energies of over a million electron volts. This was followed by a 27-inch machine, which then quickly became a 37-inch cyclotron. When news of the discovery of nuclear fission in uranium reached Berkeley in January 1939, Lawrence was planninga 60-inch cyclotron that would deliver proton energies of the order of 20 million electron volts. It would need a magnet weighing 200 tons.
The 60-inch machine was barely operational at the Rad Lab’s Crocker Laboratory before Lawrence was busy designing the next one. This was to be a gargantuan 120-inch super-cyclotron with a magnet weighing 2,000 tons. Lawrence estimated that this would deliver proton energies of 100 million electron volts, on the threshold of nuclear-scale energies. Lawrence approached the Rockefeller Foundation with requests for support. His pitch was greatly strengthened when, in the middle of a game at the Berkeley Tennis Club on 9 November, he was informed that he had just won the 1939 Nobel prize for physics.
Suitably emboldened, as Christmas approached Lawrence escalated the scale of the super-cyclotron even further, to include a magnet with 184inch pole faces (the largest diameter of commercially-available steel plate), weighing 5,000 tons. It would cost an estimated $1.5 million to build.
The outbreak of war in Europe in September had an immediate personal impact on Lawrence – after several days of anxious waiting he heard that his brother John had survived the sinking of the Athenia by a German submarine on 2 September. But life at the Rad Lab continued pretty much as normal. There were interesting experiments to be performed on uranium using the 60-inch cyclotron, but this was work that would have been carried out irrespective of the war. There was no sense yet that the Rad Lab was in any way involved in ‘war work’.
A photograph from around this time shows the Rad Lab faculty, gathered in three rows beneath the magnet of the 60-inch cyclotron. Lawrence is sitting in the centre of the front row.
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