5. In the most “down-to-earth” business of hunting for new mineral
sources;
6. For exploring the causes of Napoleon’s death nearly 150 years
earlier (see photograph on next page). Today, there is virtually no
field of science and technology that is untouched by this method.
The illustrations of _procedures_ used in the situations described in
this booklet are typical of some in use today. There are many other
situations that require still other techniques. One of the most
exciting, which will be used with increasing frequency in the future,
involves the use of computers. It has been shown that data collected by
high-resolution gamma-ray spectrometers can be “fed” directly to a
computer. The computer can be programmed to identify unknown components
and to determine the concentrations of elements of interest to the
analyst. It is entirely possible to include corrections for radioactive
decay, possible interferences from other elements present, and many
other factors. It appears quite likely that the kinds of analyses
described here (as well as others) may someday be accomplished
automatically, with far smaller chances for error and probably more
economically.
[Illustration: Hair sample]
Samples of Napoleon’s hair. Neutron activation analysis of these hairs
revealed that he had been poisoned with arsenic. (He died, however,
not from arsenic poisoning, but from acute mercury intoxication.)
Other newer techniques that may find increased usage in the future are
exemplified by the method for activation analysis of the whole human
body. The use of neutrons produced by nuclear machines (such as
cyclotrons or other particle accelerators) or produced by compact,
portable isotopic sources will make neutron activation analysis even
more versatile. Isotopic sources produce neutrons as the result of a
nuclear reaction. One such reaction uses alpha particles emitted by
polonium-210 (or some other alpha emitter) to bombard the element
beryllium. A different kind of isotopic source is the man-made
radioisotope californium-252 that decays by fissioning (splitting)
spontaneously and produces neutrons in the process. (One milligram of
californium-252 will spontaneously produce over 10⁹ neutrons per
second.) While californium-252 is quite expensive at present, it is
likely that production costs will be significantly reduced in the
future.
With computers, more convenient radiation sources, and continuing
improvements in the technology of gamma-ray detectors and nuclear
electronics, neutron activation analysis will become more and more a
routine tool of the analyst.