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How to make gold

How to make gold. by Hendrik Schatz. (stable) Elements in nature. after the Big Bang. 25% in mass. 75% in mass. ~0.00000001 %. : More than 75% made in r-process. Gold ( 197 Au). 197 Au: Au has 79 protons 197 Au has 197 – 79 = 118 neutrons. number of protons. Helium.

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How to make gold

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  1. How to make gold by Hendrik Schatz

  2. (stable) Elements in nature after the Big Bang 25% in mass 75% in mass ~0.00000001 % : More than 75% made in r-process

  3. Gold (197Au) 197Au: Au has 79 protons197Au has 197 – 79 = 118 neutrons number of protons Helium number of neutrons Hydrogen

  4. NucleusFactories

  5. Creation of new elements is energy source of stars (and the sun)

  6. The sun shines 3.85e33 erg/s = 3.85e26 Watts for at least ~4.5 bio years The entire sun made of coal would last ~ 4000 years

  7. On the way to making gold: Burning stages of a 25 solar mass star initially present: mostly hydrogen (~70% - from big bang) Hydrogen burning Hydrogen (1p,0n) Helium (2p, 2n) 7Mio yrs Helium burning Helium (2p,2n) Carbon (6p, 6n), Oxygen (8p,8n) 700,000 yrs Carbon(+Ne) burning Carbon (6p,6n) Oxygen (8p,8n) 400 yrs Oxygen burning Oxygen (8p,8n) Silicon (14p,14n) 8 months Silicon burning Silicon (14p,14n) Iron (26p,30n) 1 day

  8. For stable nuclei !!!

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

  10. Is the universe made of iron ? Hydrogen: Helium: Mass number = 1 Mass number = 4 Nuclei in the Universe: 91.0% Iron ? 8.9%

  11. … not yet Iron: Gold: 26 protons + 30 neutrons 79 protons + 118 neutrons Mass number = 56 Mass number = 197

  12. So how is gold made ? NSCL Alchemists lab + NSCL … by a nuclear reactionfor example: 198Hg + 9Be -> 197Au + p + …. Makes gold from mercury Some earlier failed attempts (1590)

  13. Iron from a previous generation of stars is exposed to a flux of neutrons • How does this create heavy elements ? • Neutron Capture Processes There are 2: - s-process (slow neutron capture) - r-process (rapid neutron capture)

  14. Where does it happen ? there ! in red giants – and it takes several million years ! (or, more correctly, low mass TP-AGB stars)

  15. How can we tell ? Analyze light from a red giant: Star contains Technetium (Tc) !!!(heavy element Z=43, T1/2 4 Mio years, Merrill 1952)

  16. The s-process makes only half of all heavy elements so where does the rest come from ?

  17. Question 3How were the elements from iron to uranium made ?

  18. Pt Xe

  19. 197Au: Au has 79 protons197Au has 197 – 79 = 118 neutrons Gold (197Au) number of protons ? Helium number of neutrons Hydrogen

  20. Where does the r-process happen ? We don’t know – here are some ideas: Supernovae ? Neutronstar merger ?

  21. r-process: status and reach of (some) RIB facilities r-process Pb RIA Reach Fe NSCL/MSU Reach Known halflife

  22. Towards the future: The Joint Institute for Nuclear Astrophysics: http://www.jinaweb.org The Rare Isotope Accelerator (RIA) at MSU ?

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