Page 9 - ILL Annual Report 2019

About the ILL
The Institut Laue Langevin (ILL) is an international research centre providing world-leading facilities in neutron science and technology. Neutrons are used at the ILL to probe the microscopic structure and dynamics of a broad range of materials at molecular, atomic and nuclear level.
The ILL operates the most intense neutron source in the world: a 58.3 MW nuclear reactor designed for high brightness. The reactor normally functions round-the-clock for four 50-day cycles per year, supplying neutrons to
a suite of 40 high-performance instruments constantly maintained at the highest state of the art.
The ILL is owned by its three founding countries—France, Germany and the United Kingdom. These three Associate countries contributed some 67 M€ to the Institute in 2019, a sum enhanced by significant contributions from the ILL’s Scientific Member countries—Austria, Belgium, the Czech Republic, Denmark, Italy, Poland, Spain, Slovakia, Sweden and Switzerland. The ILL’s overall budget in 2019 amounted to about 101 M€.
As a service institute, the ILL makes its facilities and expertise available to visiting scientists. It has a global user community of around 2 000 researchers from almost 40 countries who come to work at the ILL every year. The 850 experiments they perform annually are pre-selected by a scientific review committee. Between 550 and 600 scientific papers are published annually following the treatment and interpretation of data obtained using our facilities. Of these articles, 168 were published in high-impact journals in 2019.
NEUTRONS AND SOCIETY
The scope of the research carried out at the ILL is very broad, embracing condensed matter physics, chemistry, biology, materials and earth sciences, engineering, and nuclear and particle physics. Much of it impacts on many of the challenges facing society today, from sustainable sources of energy, better healthcare and a cleaner environment, to new materials for information and computer technology.
PREPARING FOR THE FUTURE
To maintain its status as a leader in neutron science, the Institute has constantly upgraded its instruments, infrastructure and scientific equipment over the last 50 years. The latest modernisation—the Endurance programme—will continue to develop the Institute’s instrumentation and support services with a view to maintaining its world-leading position for another decade at least. Endurance phase I is currently running, with
a second phase anticipated to run between 2020 and 2023.
WHAT IS THE ILL
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Why neutron scattering is useful
When used to probe small samples of materials, neutron beams have the power to reveal what is invisible using
other forms of radiation. Neutrons can appear to behave as particles, waves or microscopic magnetic dipoles; with these very specific properties they can provide information that is often impossible to obtain using other techniques. Below are a few of the special characteristics of neutrons.
WAVELENGTHS OF TENTHS OF NANOMETRES
Neutrons have wavelengths varying from 0.01 to 100 nanometres. This makes them ideal for probing atomic and molecular structures, whether composed of single atomic species or complex biopolymers.
ENERGIES OF MILLI-ELECTRONVOLTS
The milli-electronvolt energies associated with neutrons are of the same magnitude as the diffusive motions of atoms and molecules in solids and liquids, the coherent waves in single crystals (phonons and magnons) and the vibrational modes in molecules. Any energy exchange, therefore,
of between 1μeV (or even 1 neV with neutron spin-echo techniques) and 1eV between the incoming neutron and the sample is easy to detect.
MICROSCOPICALLY MAGNETIC
Neutrons possess a magnetic dipole moment that makes
them sensitive to the magnetic fields generated by unpaired electrons in materials. They therefore play an important role in investigating the magnetic behaviour of materials at the atomic level. In addition, as the neutron scattering effect of the atomic nuclei in a sample depends on the orientation of the spin of both the neutron and the atomic nuclei, neutron scattering techniques are ideal for detecting nuclear spin order.
ELECTRICALLY NEUTRAL
As neutrons are electrically neutral they can penetrate far into matter without doing damage. They are therefore precious allies for research into biological samples or engineering components under extreme conditions of pressure, temperature or magnetic field, or within chemical-reaction vessels.
HIGH SENSITIVITY AND SELECTIVITY
The scattering from nucleus to nucleus in a sample varies in a quasi-random manner, even for different isotopes of the same atom. This means that light atoms remain visible in the presence of heavy atoms, and atoms close to each other in the periodic table can be clearly distinguished. This makes it possible to
use isotopic substitution in order to vary the contrast in certain samples and thus highlight specific structural features.
Neutrons are also particularly sensitive to hydrogen atoms and are therefore essential for research into hydrogen storage materials, organic molecular materials, and biomolecular samples and polymers.
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