Particles, Nuclei, and the Cosmos

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. M < 8 M M > 8 M Star Formation Big Bang Supernova Star Planetary Nebula

9. Big Bang

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 Normal Nuclear Matter (F. Karsch, hep-lat/0106019) Quark Gluon Plasma Lattice QCD calculations predict the transition to occur at

14. 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 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. Range-energy calculation Particle Identification in STAR d p K+ + e+

18. Particle ID Techniques - Topology

19. 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

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. Hydrogen: Helium: Mass number = 1 Mass number = 4 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 )

30. Stage Duration Product Name Product Z Product N Hydrogen burning 7 Million yr Helium 2 2 Helium burning 700,000 yr Carbon,Oxygen 6,8 6,8 Carbon burning 400 yr Oxygen, Neon 8,10 8,10 Neon burning 1 yr Oxygen, Magnesium, Silicon 8,12,14 8,12,14 Oxygen burning 8 month Silicon, Sulfur 14,16 14,16 Silicon burning 1 day ~Iron, Nickel ~24-28 ~24-28 Burning stages of a 25 solar mass star

31. Precollapse structure of massive star Iron core collapses and triggers supernova explosion

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 N=126 N=82

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 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)

43. “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