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Microscopic matter has a life of its own: atoms vibrate,
molecules interact with each other, and proteins fold and unfold. To
watch this teeming life of the infinitesimally small, scientists
use, among other particles, neutrons. By bombarding proteins,
crystals, or any other material with neutrons, and looking at how
neutrons scatter off these materials, scientists can reveal some
aspects of their inner workings.
 Using
detectors, scientists count the scattered neutrons, measure their
energies and the angles at which they scatter, and map their final
positions – which are shown as a “diffraction pattern” of dots of
varying intensities. These patterns allow scientists to glean great
detail about the nature of materials ranging from liquid crystals to
proteins to metals.
Neutrons are particularly useful in reconstructing the positions
of materials consisting of hydrogen atoms, such as water. Since the
human body is made of 80 percent water, neutrons can be used to
determine the chemical structure of a large number of human tissues
and organs. Neutrons are also ideal to investigate the atomic
structure of other biological systems with low mass, such as
proteins and medical drugs.
Another interesting property of the neutron is that it acts like
a tiny bar magnet, allowing it to reveal details about magnetic
materials that could not be obtained by any other method.
Neutrons aimed at a magnetic material are scattered by the
material’s unpaired electrons that produce its magnetism, thus
helping scientists to determine the positions and interactions of
the material’s atoms. Such information has been vital to the
creation of high-density recording media such as audiotapes,
videotapes, compact discs, and computer disks.
The magnetic properties of neutrons are now being used in
developing smarter sensors, radiation-resistant computer data
storage devices, and faster electronic devices.
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