Close This Window

Please download official ILL logos here

 

For using on the web or on a screenFor printing in high resolutionWhite version, for dark backgrounds

Download PNG

Download AI

Download white PNG

Download JPG

 

Download white AI

About neutrons

The ILL has firmly established itself as a pioneer in neutron science and technology. Neutron beams are used to carry out frontier research in diverse fields.

Back to ILL Homepage
English French Deutsch 

About neutrons

When beams of neutrons are used to probe small samples of materials they have the power to reveal what cannot be seen using other types of radiation.  Neutrons appear to behave either as particles or as waves or as microscopic magnetic dipoles. It is these specific properties which enable them to yield information which is often impossible to obtain using other techniques.

Why use neutrons?

Wavelength

Neutron wavelengths range from 0.1 Å to 1000 Å, making them an ideal probe of atomic and molecular structures, atomic and molecular structures, both single atomic species or complex biopolymers.

 

Energy

Neutron energies are of the same magnitude as the diffusive motion in solids and liquids, the coherent waves in single crystals (phonons and magnons), and the vibrational modes in molecules. Any exchange of energy of the order of 1 μeV (even 1 neV with spin-echo) to 1 eV between a sample and an incoming neutron can be detected.

Electrical neutrality

Neutrons are non-destructive and can penetrate deep into matter. This makes them an ideal probe for biological materials and samples under extreme conditions of pressure, temperature, magnetic field or within chemical reaction vessels.

 

Scattering power

In contrast to X-rays, the neutron scattering power varies from one nucleus to another in a quasi-random manner. This means that light atoms (like Hydrogen) are visible despite the presence of heavier atoms, and neighbouring atoms may be distinguished from each other.


Magnetic moment

Neutrons possess a magnetic dipole moment which makes them sensitive to magnetic fields generated by unpaired electrons in materials.  Precise information on the magnetic behaviour of materials at atomic level can be collected. 

In addition, the neutron scattering power of an atomic nucleus depends on the respective orientations of the neutron and the nucleus spins. This makes the neutron a powerful instrument for detecting the nuclear spin order.

 


What for?

The way neutrons scatter off gases, liquids and solid matter gives us information about the structure of these materials (elastic neutron scattering). The neutron excitation of atoms gives information about the binding energy within matter (inelastic neutron scattering). Their ability to act as 'small elementary magnets' makes neutrons an ideal probe for the determination of structures and dynamics of unknown magnetic matter.

Heavy nuclei can be split with neutrons. This can shed light on a number of still unknown processes in atomic fission. Neutrons can also be captured by nuclei. The process releases secondary radiation which can be used to determine the inner structure of these nuclei.

Neutrons are used in different fields of research.

 

Condensed-matter physics, materials science and chemistry

  • Examination of the structure of new materials, for example new ceramic high-temperature superconductors or magnetic materials (important for electronic and electrical applications).
  • Clarification of still unknown phenomena in processes such as the recharging of electric batteries.
  • Storing of hydrogen in metals, an important feature for the development of renewable energy sources.
  • Analysis of important parameters (for example elasticity) in polymers (for example plastic material).
  • Colloid research gives new information on such diverse subjects as the extraction of oil, cosmetics, pharmaceuticals, food industry and medicine.

Biosciences

Biological materials, naturally rich in hydrogen and other light elements, are ideal samples for analysis with neutrons.

  • Cell Membranes
  • Proteins
  • Virus Investigations
  • Photosynthesis in Plants

Nuclear and elementary particle physics

  • Experiments on the physical properties of the neutron and the neutrino.
  • Production of extremely slow neutrons down to 5 m/s (the velocity of the neutrons which leave the reactor is generally about 2200 m/s). This enables completely new experiments to be performed with such particles.
  • Experiments on atomic fission and the structure of nuclei.

Engineering sciences

Since neutron diffraction is non-destructive, it is ideal for the analysis of different technical phenomena in materials.

  • Visualisation of residual stress in materials (example: railway rails).
  • Hardening and corrosion phenomena in concrete.
  • Inhomogeneity and trace elements in materials.