Streaming Video | Ipod-friendly Download
6.1.4.
Elementary Particle Theory <CJ chap 32 >
6.1.4.1.
Discussion
6.1.4.1.1.
Nuclear
fission:
6.1.4.1.1.1.
when heavy nuclei are split into two
more stable nuclei with energy release
6.1.4.1.2.
Nuclear
fusion:
6.1.4.1.2.1.
when light nuclei are combined at
temperatures in the sun to make heaver ones
6.1.4.1.3.
Nuclei
can be plotted in two dimensions on an A vs Z plot or an N vs Z plot showing
all nuclei
6.1.4.1.3.1.
Either plot shows every possible
nucleus and is very effective in visualizing decays
6.1.4.1.4.
Elementary
Particles: are classified into a number of categories, spin value, interaction
strength…:
6.1.4.1.4.1.
Spin: Fermions have half integer spins (½, 3/2, 5/2 ..)
, Bosons integer spins (0,1,2..)
6.1.4.1.4.2.
Strongly interacting particles are
called Hadrons (participate in the nuclear or strong force)
6.1.4.1.4.2.1.
Hadrons
that are Fermions are called Baryons e.g. p, n, S, L,
X, W …
6.1.4.1.4.2.2.
Hadrons
that are Bosons are called Mesons e.g. p, K, h, ...
6.1.4.1.4.3.
Leptons (6) are Fermions that are
not Hadrons (have no strong interactions) eg e, m, t, ne, nm, nt,
6.1.4.1.4.4.
Quarks (6): are the more fundamental
particles that compose all of the Hadrons: u, c, s, c, b, t
6.1.4.1.4.5.
Gauge particles intermediate the
forces: Gravity graviton, EM g, Weak Z, W
, Strong gluon
6.1.4.1.5.
Particles
can be specified in classes by their quantum numbers (charge, strangeness,
isospin, …)
6.1.4.1.5.1.
Particles so plotted in these
quantum number spaces have patterns as representations of groups
6.1.4.1.5.2.
These group theory patterns have
given a basic order to the more than 300 elementary particles
6.1.4.1.5.3.
The model for this group theory is
called the standard model with the following general idea:
6.1.4.1.5.3.1.
All
hadrons are composites made of quarks (eg p = (d+u+u), n = (d+d+u), p-=(d+anti u)
6.1.4.1.5.3.2.
The
6 leptons and 6 quarks have very parallel interactions for EM and Weak
interactions
6.1.4.1.6.
Cosmology
is the study of the structure and evolution of the universe
6.1.4.1.6.1.
Hubble discovered that distant
galaxies are all moving away from each other
6.1.4.1.6.1.1.
Thus
the universe is expanding, and furthermore this expansion is accelerating
6.1.4.1.6.1.2.
The
expansion should slow due to gravity but dark energy is causing the increase
6.1.4.1.6.1.3.
The
big bang is estimated to have occurred about 13.6E9 years ago
6.1.4.1.6.1.4.
The
cosmic background radiation is today at a temperature of about 2.7 K
6.1.4.1.6.2.
There are approximately 1E11 stars
in our galaxy (the Milkey Way)
6.1.4.1.6.2.1.
There
are approximately 1E11 galaxies in our universe
6.1.4.2.
Mathematical
6.1.4.2.1.
Cosmology:
6.1.4.2.1.1.
Hubble’s law of expansion: v = H d where H is the Hubble parameter 0.022 m/(s ly)
6.1.4.3.
Advanced