# Presentation: 580960

## Where Have Your Atoms Been?
The Big Bang
The Creation of the Elements

- The Big Bang
- The Creation of the Elements

***Particles, Nuclei, and the Cosmos***

**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
- 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

- 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

- 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

- 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 theory states that the universe began as a gigantic explosion
- This idea has entered popular culture

## Big

**Big**

**Bang**

**Star Formation**

**Star**

**Supernova**

**Planetary Nebula**

## 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 |

## 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

- 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

## Collision of 2 Gold Nuclei at RHIC

## Quark Gluon Plasma

**Lattice QCD calculations predict the transition to occur at**

***Quark Gluon Plasma***

## Stages of the collision

***Stages of the collision***

- time

- temperature

- “end result” looks very similar
- whether a QGP was formed or not!!!

## The Relativistic Heavy Ion Collider

## Actual Measurement - STAR at RHIC

## Particle Identification in STAR

- e+

- +

- K+

- p

- d

## Particle ID Techniques - Topology

## 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

- 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

- 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

- 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

- 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

## Binding energy per nucleon of stable nuclei

**4****Helium**

**Iron and Nickel**

## Nuclei in the Universe

- 91.0%

- 8.9%

- By weight:
- 75% Hydrogen
- 25% Helium

- Gold:

- 79 protons + 118 neutrons

- Mass number = 197

- Iron:

-  26 protons + 30 neutrons

- Mass number = 56

***Nuclei in the Universe***

## 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”

## The pp chain (the main path )

## Slide 29

## Burning stages of a 25 solar mass star

## Precollapse structure of massive star

- Iron core collapses and triggers supernova explosion

## Slide 32

## Tarantula Nebula in LMC (constellation Dorado, southern hemisphere) 

- Tarantula Nebula in LMC (constellation Dorado, southern hemisphere)
- size: ~2000ly (1ly ~ 6 trillion miles), disctance: ~180000 ly

## Supernova 1987A by Hubble Space Telescope Jan 1997

## 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”

- Solar r-abundances

- Known  mass

- Known half-life

- r process waiting point (ETFSI-Q)

- N=82

- N=126

***National Superconducting Cyclotron Laboratory****** Coupled Cyclotron Facility***

## Projectile Fragmentation RB Production

**Fragment**
**Separator**

**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.

## The Fragment Separator Principle

- H. Scheit

## Rare Isotope Beam Rates with the CCP

## 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

- 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