Neutron scattering instruments and techniques allow
us to observe how neutrons behave when they bump into (scatter
from) the materials we want to investigate. We focus a beam of
neutrons on the sample and the instruments record their behavior:
which way do they go? how fast are they traveling? do they change
direction or speed on impact? All this information helps us define
much about the material: its molecular structure, its electronic
and magnetic properties, and how we might alter them to improve
the material.
By making a sample itself radioactive, we can determine the
type and amount of "ingredients" in it. We count the
radiation with instruments that are so sensitive they can distinguish
at the "parts per billion level" by weight—one one-thousandth
of a microgram of an element among one gram of multiple elements!
This is the basis for a set of techniques called neutron activation
analysis (NAA) that provides us with a "fingerprint."
NAA is useful for studies on a variety of materials, such as
rock samples, volcanic materials, and pottery from archaeological
sites. For example, we can compare pottery sherds (bits of pottery
found at an archaeological site) with clays from different areas
to match where the clay came from to make that piece of pottery.
Many times it does not match the local soils, which means the
piece did some traveling, perhaps with migrant peoples or because
of trade or conquest. Such information provides critical pieces
for the archaeologist who assembles snapshots of prehistorical
peoples.
With a process known as neutron capture or irradiation,
we can create radioactive materials—radioisotopes—for a
variety of studies ranging from basic science to practical applications,
particularly in the broad area of life sciences. For example,
radioisotopes emit radiation that can be targeted to destroy
specific cells, such as cancerous tumors. MURR research led to
the research and development of three commercial radioisotopes:
Ceretec™, used to image blood flow abnormalities
in the brain to diagnose and assess stroke victims; TheraSphere®
for the treatment of liver cancer; and Quadramet®, a therapeutic
radiopharmaceutical designed to relieve the pain associated with
metastatic bone cancer.
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University of Missouri-Columbia
