Transcript Slide 1

Standard Model (s)
Organizing our data helps us see
deeper relationships and ultimately the
underlying laws of nature.
Standard Models
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Parts and how they go together
1) Atoms – Periodic Table
2) Nuclei – Chart of the nuclides
3) Particle Physics – Quark Ensembles
Mesons and Hadrons
4) “Bulk” Quark Matter – Quark-Gluon
Plasma
The parts of the Atomic Model and the
roles they play
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Electrons
Nuclei
Negative Charge, e Positive Charge, Ze
Small Mass
(2000 A) Large Mass
Fill the atom ((10^4)^3) Tiny at center
5x10^-11 m
(2 to 6) 10^-15 m
Volley ball (20 cm) vs. VU Campus (2 km)
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Magic numbers or shells: 2, 2+6=8, 2+6+8+10 with
10 held back, and holding back gets more
complicated beyond this
Most stable (noble) end period
Note that these are ground states
Excited states have one or more electrons of an
atom in a higher orbit.
Excited atoms decay, usually in nanoseconds, to
ground states.
Hydrogen atom decay picture on next slide.
Looks Familiar, but now antiproton at
center and positron (antielectron) circles it
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The numbers of neutrons and protons in the nucleus change.
Why can we ignore that change in making our periodic chart?
These charts are for chemistry-type energy changes, a few
kiloJoules/mole or eV/atom. Nuclear changes typically require
10^5 times as much energy.
Physicists think about single atoms while chemists think about
moles of atoms, physicists prefer to think about 1 eV of energy
rather than 6e-19 J – even though it is the same thing! You could
give the mass of a piece of jewelry in tons, but why would you
want to?
Size of atom – does not increase much with more electrons, not
as cube root of number of electrons.
What do the electrons care about in a
nucleus?
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The charge, Ze, of the nucleus and that it is
much heavier than an electron are the most
(by far) important properties of the nucleus.
Nuclear physics is a thousand to a million
times more violent than chemistry and in this
more violent world pieces can be knocked off
the nucleus.
What can nature build out of protons and
neutrons? Does nature respect rules or
magic numbers when neutrons and protons
are merged?
Let’s make a chart of Nuclei to see if there
are regularities like we found with atoms
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Vertical – Number of protons
Horizontal – Number of neutrons
There must be a new, short range, force
much stronger than the electrostatic force or
protons could not be held so close together.
Magic Numbers (either neutrons or protons)
2, 8, 20, 28, 50, 82, 126
Strong force can’t tell proton from neutron
Magic numbers of n, p – separately:
2, 8, 20, 28, 50, 82, 126, …
Bang two elements together, to get a new
element. 117 is latest. 126 coming???
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* Actinides
o 93 neptunium Np
o 94 plutonium Pu
o 95 americium Am
o 96 curium Cm
o 97 berkelium Bk
o 98 californium Cf
o 99 einsteinium Es
o 100 fermium Fm
o 101 mendelevium Md
o 102 nobelium No
o 103 lawrencium Lr
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* Transactinide elements
o 104 rutherfordium Rf
o 105 dubnium Db
o 106 seaborgium Sg
o 107 bohrium Bh
o 108 hassium Hs
o 109 meitnerium Mt
o 110 darmstadtium Ds
o 111 roentgenium Rg
o 112 copernicium Cn
o 113 ununtrium Uut*
o 114 ununquadium Uuq*
o 115 ununpentium Uup*
o 116 ununhexium Uuh*
o 117 ununseptium Uus*
o 118 ununoctium Uuo*
A cyclotron in Dubna accelerates a beam
of Ca48 to hit a 22 mg Bk249 target
The Building blocks of the
next level standard model
27 particle physicists have
won Nobel prizes for
making the experimental
discoveries and theoretical
breakthroughs that led to
our present understanding.
The Higgs boson?
Interesting to remember
that 35 years ago only knew
up, down, strange, e, muon,
2 neutrinos, and the photon.
Particle – anti particle reminder. All those
quarks and and leptons have antis too
And there are antiquarks corresponding to
each quark.
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Charge
+2/3
-1/3
quark flavor
up, charm, top
down, strange, bottom
Anti on each
-2/3
u, c, t
+1/3
d, s, b
Quark Chemistry
Baryons: 3 quarks, Antibaryons: 3 antiquarks
p = 2 up + down; n = 2 down + up
Mesons: a quark and an antiquark
pi = up + anti down
When we only knew about 3 quarks (up to
1975), we could summarize it (spin ½)
Or for spin 3/2 combinations
Spin 0 Mesons
And for Spin 1 Mesons
LHC Accelerator
Protons are accelerated by
powerful electric fields to very
close to the speed of light.
And are guided around their
circular orbits by powerful
superconducting dipole magnets.
The dipole magnets operate at 8.3
Tesla (200’000 x Earth’s magnetic
field) & 1.9 K (-271°C) in
superfluid helium.
Protons travel in a tube which is
under a better vacuum and at a
lower temperature than that in
inter-planetary space.
wrt Tevatron (USA)
Energy (7-14 TeV)
x 3.5-7
No. of interactions/second x 30