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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. History of the Universe. Where Have Your Atoms Been?. The universe was created in the big bang 13 to 15 billion years ago

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

Gary D. WestfallMichigan State University

where have your atoms been
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
nuclear physics primer
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
more nuclear physics primer
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
particle primer
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
the big bang
The Big Bang
  • The big bang theory states that the universe began as a gigantic explosion
  • This idea has entered popular culture

M < 8 M

M > 8 M

Star Formation





Planetary Nebula

history of the idea of the big bang
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
the evolution of the early universe
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
quark gluon plasma

Quark Gluon Plasma

Normal Nuclear Matter

(F. Karsch, hep-lat/0106019)

Quark Gluon Plasma

Lattice QCD calculations predict the transition to occur at

stages of the collision

The “little bang”

  • pre-equilibrium (deposition of initial energy)
  • rapid (~1 fm/c) thermalization (?)

QGP formation (?)

hadronization transition

(poorly understood)

hadronic rescattering

Chemical freeze-out: end of inelastic scatterings

Kinetic freeze-out: end of elastic scatterings

Stages of the collision



“end result” looks very similar

whether a QGP was formed or not!!!

azimuthal distributions

pedestal and flow subtracted

Azimuthal Distributions

Near-side: p+p, d+Au, Au+Au similar

Back-to-back: Au+Au strongly suppressed relative to p+p and d+Au

Suppression of back-to-back correlation in Au+Au is final-state effect

after 0 01 s
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
learning from deuterium
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
the universe becomes transparent
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)
problems with the big bang model
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



Mass number = 1

Mass number = 4

Nuclei in the Universe



By weight:

75% Hydrogen

25% Helium

nuclei in the universe
Nuclei in the Universe



26 protons + 30 neutrons

79 protons + 118 neutrons

Mass number = 56

Mass number = 197


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”




Product Name

Product Z

Product N

Hydrogen burning

7 Million yr




Helium burning

700,000 yr




Carbon burning

400 yr

Oxygen, Neon



Neon burning

1 yr

Oxygen, Magnesium, Silicon



Oxygen burning

8 month

Silicon, Sulfur



Silicon burning

1 day

~Iron, Nickel



Burning stages of a 25 solar mass star


Precollapse structure of massive star

Iron core collapses and triggers supernova explosion


Tarantula Nebula in LMC (constellation Dorado, southern hemisphere)

size: ~2000ly (1ly ~ 6 trillion miles), disctance: ~180000 ly


Supernova 1987A seen by Chandra X-ray observatory, 2000

Shock wave hits inner ring of material and creates intense X-ray radiation


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


The r process “path”

Known mass

Known half-life

r process waiting point (ETFSI-Q)

Solar r-abundances



projectile fragmentation rb production
Projectile Fragmentation RB Production

Fragments are made

at near beam velocity



Example: 11Be from 13C at 100 MeV/A (b=.42) would have a momentum FWHM of 5% and an angular cone of 6 degrees.

science with radioactive beams
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 Z=16.
  • 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)
facing the future

“The Future’s So Bright I Gotta Wear Shades!”

-Timbuk 3

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