Splitting the Atom
In 1932 the physicists John Cockcroft and Ernest Walton, at the Cavendish Laboratory in Cambridge, devised a technique for bombarding atomic nuclei with protons (hydrogen nuclei) that had been accelerated in a powerful electric field. The aim of these attempts to 'split the atom' was to explore the basic composition of matter.
Scientists had been theorising for some time about what atoms were like and how they behaved. The Swiss, Heinrich Greinacher, published a paper in 1921 on how such an experiment might work in practice - Cockcroft and Walton were the first to conduct those experiments successfully.
Experiments to investigate atoms and sub-atomic particles required huge pieces of apparatus to generate the high voltages needed. The growth of this experimental apparatus started in 1930, when Cockcroft and Walton developed a voltage-multiplying circuit that used capacitors (components used to store energy) to produce high voltage direct current (DC) from a much lower alternating current (AC). They erected a column of rectifier diodes (which allow the electrical current to move forwards but prevent it from moving back again) and capacitors to produce a DC voltage four times greater than the AC voltage.
These experiments showed that the atomic nucleus was not an indivisible and basic unit, but had its own internal structure. This included the newly-revealed sub-atomic particles which were 'broken out' of the nucleus by these experiments. This growing understanding of atomic structure and of atomic disintegration led during the 1930s directly to ideas for atomic power and the atomic bomb.
The machine shown here is the cascade generator, built by Philips of Eindhoven in 1937, and installed in the Cavendish Laboratory. It was designed to produce the-then high voltage (up to 1.25 million volts) required to accelerate the particles.
During the Second World War the machine was used to investigate the properties of uranium and plutonium as a contribution to the Manhattan Project which manufactured the first atomic bombs. It was succeeded by a more efficient American-designed cyclotron, which itself was obsolescent by the end of the war.
Cockcroft and Walton were recognised for their pioneering work in this field in 1951 when they won the Nobel Prize for Physics. Much-refined (and miniaturised) Cockcroft-Walton circuits are still used in particle accelerators. They also are used in everyday electronic devices that require high voltages, such as X-ray machines, cathode-ray tube television sets, microwave ovens and photocopiers.
The Science Museum in South Kensington, London, acquired the Cockcroft-Walton Voltage Multiplier in 1982.
This is a clearer version of a colour image I posted a number of years ago.
Splitting the Atom
In 1932 the physicists John Cockcroft and Ernest Walton, at the Cavendish Laboratory in Cambridge, devised a technique for bombarding atomic nuclei with protons (hydrogen nuclei) that had been accelerated in a powerful electric field. The aim of these attempts to 'split the atom' was to explore the basic composition of matter.
Scientists had been theorising for some time about what atoms were like and how they behaved. The Swiss, Heinrich Greinacher, published a paper in 1921 on how such an experiment might work in practice - Cockcroft and Walton were the first to conduct those experiments successfully.
Experiments to investigate atoms and sub-atomic particles required huge pieces of apparatus to generate the high voltages needed. The growth of this experimental apparatus started in 1930, when Cockcroft and Walton developed a voltage-multiplying circuit that used capacitors (components used to store energy) to produce high voltage direct current (DC) from a much lower alternating current (AC). They erected a column of rectifier diodes (which allow the electrical current to move forwards but prevent it from moving back again) and capacitors to produce a DC voltage four times greater than the AC voltage.
These experiments showed that the atomic nucleus was not an indivisible and basic unit, but had its own internal structure. This included the newly-revealed sub-atomic particles which were 'broken out' of the nucleus by these experiments. This growing understanding of atomic structure and of atomic disintegration led during the 1930s directly to ideas for atomic power and the atomic bomb.
The machine shown here is the cascade generator, built by Philips of Eindhoven in 1937, and installed in the Cavendish Laboratory. It was designed to produce the-then high voltage (up to 1.25 million volts) required to accelerate the particles.
During the Second World War the machine was used to investigate the properties of uranium and plutonium as a contribution to the Manhattan Project which manufactured the first atomic bombs. It was succeeded by a more efficient American-designed cyclotron, which itself was obsolescent by the end of the war.
Cockcroft and Walton were recognised for their pioneering work in this field in 1951 when they won the Nobel Prize for Physics. Much-refined (and miniaturised) Cockcroft-Walton circuits are still used in particle accelerators. They also are used in everyday electronic devices that require high voltages, such as X-ray machines, cathode-ray tube television sets, microwave ovens and photocopiers.
The Science Museum in South Kensington, London, acquired the Cockcroft-Walton Voltage Multiplier in 1982.
This is a clearer version of a colour image I posted a number of years ago.