Neutron Basics
A neutron is one of the fundamental particles that make up matter. This uncharged particle exists in the nucleus of a typical atom, along with its positively charged counterpart, the proton. Protons and neutrons each have about the same mass, and both can exist as free particles away from the nucleus. In the universe, neutrons are abundant, making up more than half of all visible matter.
How Can Neutrons Be Used for Research?
Neutron imaging techniques have been able to determine the precise movement of glucose in plants. This knowledge can help scientists better understand how biomass can be efficiently converted into fuel.
Neutrons have many properties that make them ideal for certain types of research. Because of their unique sensitivity to hydrogen, neutrons can be used to precisely locate hydrogen atoms, enabling a more accurate determination of molecular structure, which is important for the design of new therapeutic drugs. Neutrons scattered from hydrogen in water can locate bits of moisture in fighter jet wings—signs of microscopic cracking and early corrosion that pinpoint the part of the wing that should be replaced.
Besides hydrogen, neutrons can locate other light atoms among heavy atoms. This capability is helping scientists to open the field of quantum superstates, such as superconductivity and superfluidity. Researchers are making measurements of the atomic momentum distribution of liquid 4He and are looking for a 4He supersolid state. They have determined the critical positions of light oxygen atoms in promising high-temperature, superconducting materials.
Electron microscopy image of polyglutamine fibrils, determined to play a key role in the development of diseases such as Huntington's and Parkinson's.
Because the energies of thermal neutrons almost match the energies of atoms in motion, neutrons can be used to track molecular vibrations and movements of atoms of a protein during catalytic reactions. Recent studies with neutrons have revealed the earliest structural formation of the disease type of the protein Huntington's, and that research is moving forward to study protein malformation responsible for Alzheimer's and Parkinson's diseases.
Properties of Neutrons
- Neutrons are NEUTRAL particles. They
- are highly penetrating,
- can be used as nondestructive probes, and
- can be used to study samples in severe environments
- Neutrons have a MAGNETIC moment. They can be used to
- study microscopic magnetic structure,
- study magnetic fluctuations, and
- develop magnetic materials
- Neutrons have SPIN. They can be
- formed into polarized neutron beams,
- used to study nuclear (atomic) orientation, and
- used for coherent and incoherent scattering.
- The ENERGIES of thermal neutrons are similar to the energies of elementary excitations in solids. Both have similar
- molecular vibrations,
- lattice modes, and
- dynamics of atomic motion.
- The WAVELENGTHS of neutrons are similar to atomic spacings. They can determine
- structural sensitivity,
- structural information from 10-13 to 10-4 cm, and
- crystal structures and atomic spacings.
- Neutrons "see" NUCLEI. They
- are sensitive to light atoms,
- can exploit isotopic substitution, and
- can use contrast variation to differentiate complex molecular structures.
