Features
- Study of condensed state of matter structure in nuclear reactors or spallation
sources
- Very sensitive detectors, adapted to low density scattered fluxes
- Length adapted to the neutron flux dimensions
- Diameters and thicknesses adapted to angular accuracy or Time-of-Flight
measurement accuracy
- Helium-3 pressure depending on neutron wavelength and flux density
- Associated charge amplifiers for optimizing detector characteristics
Description
Neutron scattering is a first-class technics for the study of condensed matter. In particular, it
permits to explain and thus to improve the matter properties.
Actually, the thermal neutron wavelength (1.8 Angstrom) may be compared with
reticular distances encountered in the condensed matter.
Neutrons, as non electrically charged particles, interact with the nuclei of
matter (hydrogen included), which is of much interest for studying organic or
biological matter. Neutrons are thus complementary to X-rays which interact
at the electronic shell level of heavy atoms. In other respects, the existence
of an electronic spin and an associated magnetic momentum can be taken into
account for accurate study of magnetic materials.
Neutron scattering techniques have considerably spreaded since the creation
of very dense neutron fluxes around nuclear research reactors or spallation
sources.
Fast neutrons, produced in fission reactions of enriched Uranium within nuclear
reactors or when accelerated charged particles, interact with heavy atomic targets
within spallation sources and are then slowered or thermalized by using a moderator
(graphite or hydrogenized material).
The associated wavelengths are generally within the 1 to 10 Angstrom range.
Some wavelengths can be selected with the help of a monocrystal oriented in
a Bragg reflecting direction (monochromator) or with the help of neutron absorbing
opened disks rotating at high speeds (mechanical selector or chopper).
