As scientists hoping to probe the atomic structure of everything from cheese to aircraft wings queue up to use the latest facilities at Harwell’s Isis neutron source, this article from half a century ago reported on the dawn of the UK’s advanced neutron research.
The Harwell Neutron project, carried out at what was then the headquarters of the Atomic Energy Research Establishment, was set up largely to advance neutron science and with it the development of nuclear reactor technology — one of the site’s prime focuses.
Reporting on the opening of the neutron lab, The Engineer wrote that ‘the equipment — a pulsed source for neutron physics experiments — is intended to provide information about the detailed behaviour of neutrons of known velocities when they meet the materials used in the construction of reactors.’
The system was effectively a combined particle accelerator and neutron booster that fired neutrons towards experimental stations at the end of a series of so-called ‘flightpaths’.
Describing the instrument’s operation The Engineer reported that: ‘A pulsed beam of electrons is first generated in a linear accelerator, which increases the energy of the electron pulses to about 30MeV, the pulses being of about ¼ microsecond duration at a frequency of about 750 pulses/sec. At the remote end of the accelerator these are allowed to bombard a mercury target, which has the dual role of producing x-rays and removing the heat generated in stopping the beam.
‘These rays are then absorbed in uranium to produce neutrons by photo-disintegration and by photo-fission.’