Page 19 - Neutrons for Sciences and Society

water12, surrounded by a heavy water reflector. This gives rise to a peak flux of thermal neutrons in this reflector, several centimetres outside the core itself. Looking at this zone, tangential beam tubes lead away the thermal neutrons. This minimises the background due to the fast and epithermal neutrons, and the gamma rays coming directly from the reactor core. This layout was of course re-used for the ILL’s reactor. Herbert Kouts took responsibility for the detailed design of the Brookhaven reactor which was completed in 1965. This name will again figure in the ILL’s reactor project.
1.1 The situation in Europe
Research using neutrons could only begin in Europe after the end of the war, gaining the USA several years’ advantage. The UK, where numerous scientists had participated directly across the Atlantic, was the first to operate a reactor (GLEEP) from August 1947, followed a year later by BEPO, a more powerful reactor where neutron diffraction experiments could be performed.
The situation in France and Germany, the two countries who founded the ILL is of prime importance here, but the other countries should not be forgotten. The Netherlands and Norway jointly used a reactor at Kjeller in Norway from 1951, Denmark had its own in 1957 in Risø. In Poland a reactor was inaugurated in 1958. In Italy researchers had a source in the Euratom research
12 2018 addition: In naturally occurring water, H2O, one molecule in 41 million is made up of D2O, where the hydrogen isotope deuterium, D, is present. This has an additional neutron in the nucleus. The deuterium can be extracted and used to produce D2O, heavy water, which has some very different properties from light water, H2O, notably absorbing neutrons much less.
Chapter 1 - Pre-history
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