May 28, 2010
Serway and Jewett Chapter 30 – Nuclear Physics
Who cares about nuclear physics?
Especially for biologists, for whom it would seem that the relevant size
objects are enzymes (10 nm) or a people (1m), learning more about the
nucleus (1fm) than its charge
and atomic mass
is going too far!
For example, except for the actual and perceived biological hazards of
solution to the energy
problem [foreign oil, depletion of fossil fuels, rising levels of pollution,
Nuclear magnetic resonance imaging (MRI) is a great way to see the
chemical and physical structure of a human body with sub-mm resolution.
Subatomic particles are used for killing tumor cells, and muons are
proposed by UCR’s Prof. Nagamine as a relatively noninvasive probe of
are widely used for measuring properties of biomaterials via
(tritium), and S
are commonly used in bio labs to
trace the components of chemical reactions and to separate proteins
(Southern blotting) and DNA.
Positron emission tomography (
) uses O
to locate and
image hungry tumors in the brain and as an alternative to computed x-ray
tomography (CAT) scans for diagnosis of ischemia.
, invented by Anthony Turkevich
(1916-2002) is used to tell the elemental surface composition
of a rock or other sample.
“Surveyors V, VI, and VII were
successful, and all three carried Tony’s analytical devices:
foremost, an alpha-particle backscattering instrument that not
only gave us the first complete elemental composition of the
lunar surface but also showed that the Moon is a differentiated
body, not a homogeneous conglomerate such as a giant
chondrite, which was the prevailing view at that time. Surveyor
V, landing on September 11, 1967, at Mare Tranquillitatis, showed that
there are basalt-like materials—essentially cold lava on the lunar surface.”
Biographical memoir, National Academy of Sciences, 2007
If the target nucleus has mass number
, an alpha particle (
=4) of energy
will backscatter with energy
Besides all this, it is good to be informed about topics that other people
might use to make you do what they want if you are credulous, and to
have some inkling of how the world is framed and what are its immutable
laws and how amazing it is that there are living creatures courageous
enough to subject their sacred hypotheses to the arbiter of truth.
: What is the arbiter of truth? (a) Mathematical theory; (b) Experiment;
(c) Writings in a sacred book; (d) Opinion polls; (e) The Courts.
Backscattered energy vs.