Work Package 4
MATERIAL CHARACTERIZATION WITH NEUTRONS
MATERIAL CHARACTERIZATION WITH NEUTRONS
The moderator is almost synonymous with a neutron source: it is the device that turns the raw, very high energy neutrons into lower energy neutrons suitable for scientific experiments. In the case of HighNESS, the desired neutron energies are particularly low, being in the cold, very cold and ultra-cold regimes. Such energies require moderators composed of light atoms, able to steal most of the energy of the neutrons coming from the spallation target, but without absorbing them or otherwise affecting their intensity.
The main new ESS source, or moderator, of cold neutrons will consist of a vessel of liquid deuterium or “heavy hydrogen”. The ultra-cold neutrons will require yet another moderator, made of liquid helium; whether or not the very cold neutrons require a separate moderator is an open question.