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Where Have Your Atoms Been?

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Particles, Nuclei, and the Cosmos Where Have Your Atoms Been? The Big Bang The Creation of the Elements Gary D. Westfall Michigan State University – PowerPoint PPT presentation

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Title: Where Have Your Atoms Been?


1
Particles, Nuclei, and the Cosmos
  • Where Have Your Atoms Been?
  • The Big Bang
  • The Creation of the Elements

Gary D. WestfallMichigan State University
2
History of the Universe
3
Where Have Your Atoms Been?
  • The universe was created in the big bang 13 to 15
    billion years ago
  • The hydrogen in the water in your body was
    created then
  • More complex atoms had to be cooked inside stars
  • Several generation of stars had to pass with the
    most massive stars exploding
  • Interstellar gas was enriched with heavier
    elements
  • Interstellar dust formed containing these elements

4
Nuclear Physics Primer
  • Energies are measured in electron volts
  • 1 eV is the energy acquired by a particle with
    charge 1 accelerated across a voltage of 1 volt
  • keV - 1000 eV
  • MeV - 1,000,000 eV, 1 million eV
  • GeV - 1,000,000,000 eV, 1 billion eV
  • Using the famous Einstein relation E mc2,
    masses are also measured in eV
  • Mass of an electron 511 keV 0.511 MeV
  • Mass of a proton 939 MeV 0.939 GeV
  • A nucleon is a neutron or a proton

5
More Nuclear Physics Primer
  • The binding energy of a nucleus is about 8
    MeV/nucleon
  • Beam energies are often given in GeV/nucleon
  • RHIC is one nucleus with 100 GeV/nucleon
    colliding with another nucleus with 100
    GeV/nucleon going the opposite direction
  • The size of a nucleus is 1.2A1/3 fm where A is
    the mass number and a fm is 10-15 m
  • Nuclei are much too small to be seen with visible
    light
  • A probe is necessary to study nuclei
  • In our case, we will other other nuclei

6
Particle Primer
  • There are six flavors of quarks
  • Up, down, strange, charm, bottom, and top
  • You and I are made of up and down quarks
  • The nucleons in our atoms each have three quarks
    (proton - up, up, down)
  • Pions (?, ?-, ?0) are composed of up and down
    quarks as quark/anti-quark pairs
  • Kaons (K, K-, various kinds of K0) have a
    strange quark
  • Quarks interact by exchanging gluons
  • Nucleons are held together by gluons
  • Free quarks have never been seen
  • Quarks have a distinctive non-integer charge that
    would make them stand out from other charged
    particles
  • 1/3,2/3,-1/3,-2/3

7
The Big Bang
  • The big bang theory states that the universe
    began as a gigantic explosion
  • This idea has entered popular culture

8
Star Formation
Big
Bang
Supernova
Star
Planetary Nebula
9
Big Bang
Time Temperature Size Composition
10-43 s 1032K Quarks, gluons, electrons, neutrinos
1ms 12 trillion K 1.4 light days Protons and neutrons
1s 10 billion K 4 ly Proton and neutron ratio fixed
100s 5min 1-0.4 billion K 55 ly Nuclei are formed
500000 yr 3000 K 1.5 million ly Atoms form, photons roam freely
10
History of the Idea of the Big Bang
  • Georges Lemaitre proposed a big bang-like theory
    in the early 1920s involving fission
  • In the 1940s, George Gamov proposed the a big
    bang model incorporating fusion
  • Since that time, many astronomers and physicists
    have added their work to what is now known as the
    standard model of the big bang
  • Three main ideas underlie the big bang model
  • The universe cools as it expands
  • In very early times, the universe was mostly
    radiation
  • The hotter the universe, the more energetic
    photons are available to make matter and
    anti-matter

11
The Evolution of the Early Universe
  • With the three previous ideas in mind, we can
    trace the evolution of the universe back to when
    it was 0.01 s old and had a temperature of 100
    billion K
  • We can go back farther but not all the way to
    zero time
  • At 10-43 s most of our physical laws become
    impractical
  • At times before 0.01 s, the universe was filled
    with quarks and gluons
  • Recreate with RHIC Collisions

12
Collision of 2 Gold Nuclei at RHIC
13
Quark Gluon Plasma
Lattice QCD calculations predict the transition
to occur at
14
Stages of the collision
time
temperature
end result looks very similar whether a QGP was
formed or not!!!
15
The Relativistic Heavy Ion Collider
16
Actual Measurement - STAR at RHIC
17
Particle Identification in STAR
d
p
K
?
e
18
Particle ID Techniques - Topology
19
Azimuthal Distributions
Near-side pp, dAu, AuAu similar Back-to-back
AuAu strongly suppressed relative to pp and dAu
Suppression of back-to-back correlation in AuAu
is final-state effect
20
After 0.01 s
  • Our picture after 0.01 s is that the universe was
    filled with radiation and with types of matter
    that exist today
  • Protons and neutrons
  • Photons and neutrinos
  • The temperature was no longer hot enough to
    create neutrons and protons in collisions of
    photons
  • At about 3 minutes, nuclei begin to form
  • 75 hydrogen, 25 helium, some lithium

21
Learning from Deuterium
  • All the deuterium in the universe was formed in
    the first 3 minutes
  • If the universe was very hot and dense when the
    deuterium formed, it would have been broken up
  • If the universe expanded and then out thinned out
    rapidly, deuterium would survive
  • The density extracted from the surviving
    deuterium is 5 x 10-31 g/cm3
  • Suggests a low enough mass that the universe is
    open
  • Dark matter may still play a role

22
The Universe Becomes Transparent
  • For several hundred thousand years the universe
    resembled the interior of a star
  • After that time, atoms began to form
  • The universe became transparent
  • Radiation and matter decoupled
  • 1 billion years after the big bang, stars and
    galaxies began to form
  • The radiation from the big bang faded but it left
    an indelible fingerprint, the cosmic background
    radiation (CBR)

23
Problems with the Big Bang Model
  • The standard big bang model explains many things
    but there are remaining issues
  • It does not explain why there is more matter than
    antimatter in the universe
  • It does not explain the observed uniformity of
    the universe
  • Parts of the universe could never have been in
    contact yet they show the same background
    temperature
  • It does not explain why the density of the
    universe is close to the critical density

24
Binding energy per nucleon of stable nuclei
4Helium
Iron and Nickel
25
Nuclei in the Universe
91.0
8.9
By weight 75 Hydrogen 25 Helium
26
Nuclei in the Universe
Iron
Gold
26 protons 30 neutrons
79 protons 118 neutrons
Mass number 56
Mass number 197
27
The Sun
  • Has been emitting 3.8 x 1026 W for about 4.5
    billion years
  • Temperature at center 15 Million ?K
  • Density at center 150 g/cm3
  • Where does this energy come from ? Early ideas
  • Fossil fuels last 1000 years
  • Meteorite impacts would change earths period by
    2s/year
  • Slow contraction lasts 100 Million years

1920 Sir Arthur Eddington nuclear energy (10
billion years)We do not argue with the critic
who urges that the stars are not hot enough for
this purpose. We tell him to go and find a hotter
place
28
The pp chain (the main path )
29
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30
Burning stages of a 25 solar mass star
31
Precollapse structure of massive star
Iron core collapses and triggers supernova
explosion
32
(No Transcript)
33
Tarantula Nebula in LMC (constellation Dorado,
southern hemisphere) size 2000ly (1ly 6
trillion miles), disctance 180000 ly
34
Supernova 1987A by Hubble Space Telescope Jan 1997
35
Supernova 1987A seen by Chandra X-ray
observatory, 2000
Shock wave hits inner ring of material and
creates intense X-ray radiation
36
HST picture Crab nebula SN July 1054 AD Dist
6500 ly Diam 10 ly, pic size 3
ly Expansion 3 mill. Mph (1700
km/s) Optical wavelengths Orange H Red
N Pink S Green O Pulsar 30 pulses/s
37
The r process path
Known mass
Known half-life
r process waiting point (ETFSI-Q)
Solar r-abundances
N126
N82
38
National Superconducting Cyclotron Laboratory
Coupled Cyclotron Facility
39
Projectile Fragmentation RB Production
Fragments are made at near beam velocity
Fragment Separator
Example 11Be from 13C at 100 MeV/A (b.42)
would have a momentum FWHM of 5 and an angular
cone of 6 degrees.
40
The Fragment Separator Principle
H. Scheit
41
Rare Isotope Beam Rates with the CCP
42
Science with Radioactive Beams
  • The origin of the elements quantitative
    understanding of astrophysical processes
    r-process nuclei, X-ray bursts, begin electron
    capture and neutrino interaction measurements
    with unstable beams
  • The limits of nuclear stability What
    combinations of neutrons and protons are particle
    stable? We hope to map the neutron drip line up
    to Z16.
  • Properties of nuclei with extreme neutron to
    proton ratios An extreme challenge to many-body
    theory. Neutrons and protons at vastly different
    Fermi levels in the nucleus.
  • Properties of bulk neutron matter and the nature
    of neutron stars Study of neutron star material
    and toward the neutron matter equation of state.
    Observables in heavy-ion reactions can
    potentially be related to the nuclear EOS.
  • Study at NSCL and the proposed Rare Ion
    Accelerator (RIA)

43
Facing the Future
  • If the mass density of the universe is high
    enough, the expansion of the universe will
    reverse and the universe will collapse
  • The Big Crunch
  • If the mass density of the universe is low
    enough, the universe will expand forever and
    slowly die out
  • At critical density, the universe can just barely
    expand forever
  • Flat universe
  • Zero curvature
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