Alchemy of the Universe

1. Alchemy of the Universe The Nucleosynthesis of Chemical Elements Dr. Adriana Banu, James Madison University January 22, Saturday Morning Physics’11

2. Big questions We knew for long time that our energy comes from Sun! But what produces it in the Sun? Gravity (which governs planets motion)?! Chemical reactions like on Earth (fuel burning, explosions...)?! In the 1930s we got the answer: nuclear reactions! Namely fusion! What about the other stars?!  2. How were/are the chemical elements created? (nucleosynthesis)The answer is still: nuclear reactions! But which reactions?! How they proceed?! 3. Did nucleosynthesis stop, or continues today?

3. “If in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? Everything is made of atoms.” “If you want to make an apple pie from scratch, you must first create the universe…” “We are star-stuff…” • Richard Feynman Nobel Prize in Physics, 1965 - Carl Sagan

4. air water earth fire • From Aristotle to Mendeleyev In search of the building blocks of the universe… Greek philosophers 4 building blocks 18th-19th century Lavoisier, Dalton, … distinction between compounds and pure elements atomic theory revived 92 building blocks (chemical elements) Periodic Table of Elements 1896 Mendeleyev

5. THEATOM electrons THE NUCLEUS not to scale

6. Atom = nucleus + electrons -e (10-10 m) +Ze Nucleus =protons + neutrons (10-14m)

7. Modern “Alchemy”: radioactivity 1896 Becquerel discovers radioactivity The Nobel Prize in Physics 1903 A. H. Becquerel Pierre Curie Marie Curie  emission of radiation from atoms  3 types observed: ,  and  “transmutation” (Helium)

8. A X Z N 118 118 118 Sn Sn Sn 50 50 68 • Chart of the Nuclides ~ 3000 currently known nuclides ~ 270 stables only ! ~ 7000 expected to exist Color Key: Stable + emission - emission  particle emission Spontaneous fission Z N A chemical element (X) is uniquely identified by the atomic numberZ ! Nuclides that have the same Z but different N are called isotopes! Mass number: A = N + Z

9. CHEMICAL ELEMENTS IN YOUR BODY BY WEIGHT Oxygen (65%) Carbon (18%) Hydrogen (10%) Nitrogen (3%) Calcium (1.5%) Phosphorus (1.0%) Potassium (0.35%) Sulfur (0.25%) Sodium (0.15%) Magnesium (0.05%) BUT ALSO Copper, Zinc, Selenium, Molybdenum, Fluorine, Chlorine, Iodine, Manganese, Cobalt, Iron (0.70%) Lithium, Strontium, Aluminum, Silicon, Lead, Vanadium, Arsenic, Bromine (trace amounts)

10. = + - M ( Z , N ) Zm Nm BE p n • Nuclear Masses and Binding Energy The binding energy is the energy required to dissasemble a nucleus into protons and neutrons. It is due to the strong nuclear force! mp = proton mass, mn = neutron mass, m(Z,N) = mass of nucleus with Z protons and N neutrons

11. He-4 (2 protons + 2 neutrons)  Radium-226 (88 protons + 138 neutrons) Radon-222 (86 protons + 136 neutrons) Thanks to E=mc2, tiny amounts of mass convert into huge energy release… 1 kg of radium would be converted into 0.999977 kg of radon and alpha particles. The loss in mass is only 0.000023 kg= 23 mg! Energy = mc2 = mass x (speed of light)2 = 0.000023 x (3 x 108)2 = 2.07 x 1012 joules. Equivalent to the energy from over 400 tonnes of TNT!!! 238Pu 1 kg Ra (nuclear)  4*105 kg TNT (chemical)

12. Modern “Alchemy”:nuclear fusion and fission The process through which a large nucleus is split into smaller nuclei is called fission. Fusion is the opposite! Fission and fusionare a form of elemental transmutation because the resulting fragments are not the same element as the original nuclei. Nuclear fusion occurs naturally in stars !

13. A1 A2 A3 A4 A1 + A2 = A3 + A4 Z1 + Z2 = Z3 + Z4 Z3 Z4 Z2 Z1 • NuclearReactions X + Y  A + B (mass numbers) Conservation laws: (atomic numbers) Amount of energy liberated in a nuclear reaction (Q-value): Qval = [(m1 + m2) – (m3 + m4)]c2 definition initial final in stars Qval > 0: exothermic process (release of energy) Qval < 0: endothermic process (absorption of energy)

14. Stability and Binding Energy Curve Qval >0 fission Qval >0 fusion Qval <0 fusion

15. What Is the Origin of the Elements?

16. (full) Big-Bang nucleosynthesis Stellar nucleosynthesis all elements formed from protons and neutrons sequence of n-captures and  decays soon after the Big Bang elements synthesised inside the stars nuclear processes well defined stages of stellar evolution • Nucleosynthesis: the synthesis ofElementsthrough Nuclear Reactions Two original proposals: Alpher, Bethe & Gamow (“  ”) Phys. Rev. 73 (1948) 803 Burbidge, Burbidge, Fowler & Hoyle (B2FH) Rev. Mod. Phys. 29 (1957) 547 The Nobel Prize in Physics 1967 The Nobel Prize in Physics 1983 Which one is correct?

17. A = 8 A = 5 BBN • Big Bang Nucleosynthesis • occurred within the first 3 minutes of the • Universe after the primordial quark-gluon plasma • froze out to form neutrons and protons • BBN stopped by further expansion and cooling • (temperature and density fell below those required • for nuclear fusion) • BBN explains correctly the observed mass abundances • of1H (75%),4He (23%),2H (0.003%),3He (0.004%),trace • amounts (10-10%) of Li and Be, and no other heavy elements Mass stability gap at A=5 and A=8 !!! No wayto bridge the gap through sequence of neutron captures during BB …

18. After that, very little happened in nucleosynthesis for a long time. It required galaxy and star formation via gravitation to advance the synthesis of heavier elements. Because in stars the reactions involve mainly charged particles, stellar nucleosynthesis is a slow process. temperature and density too small !!! matter coalesces to higher temperature and density…

19. element mixing thermonuclear reactions • Stellar life cycle BIRTH gravitational contraction Stars Interstellar gas + metals DEATH explosion  • energy production • stability against collapse • synthesis of “metals”

20. Hydrogen Burning • slow or fast (explosive) H-burning • almost 95% of all stars spend their lives burning the H in their core (including • our Sun). Our Sun is a slow nuclear reactor (a fusion reactor we could not make!) OUR SUN ~16,000,000 DEGREES

21. until hydrogen fuel is depleted  the life time of our sun depends on the nuclear reaction rates life time of stars depends on their mass: at larger masses burn faster! We are lucky!

22.    8Be unstable ( ~ 10-16 s) • Helium Burning: Carbon formation • BBN produced no elements heavier than Li due to the absence of a stable • nucleus with 8 nucleons • in stars12C formation set the stage for the entire nucleosynthesis of • heavy elements How is Carbon synthesized in stars? T ~ 6*108 K and  ~ 2*105 gcm-3 4He + 4He  8Be 8Be + 4He  12C

23. Helium Burning: Oxygen formation • Oxygen production from carbon: 12C + 4He →16O +  Carbon consumption ! Reaction rate is very small  not all C is burned, but Oxygen production is possible and Carbon-based life became possible…

24. T ~ 1.2*109 K  ~ 4*106 gcm-3  Neon burning T ~ 3*109 K  ~ 108 gcm-3  Silicon burning major ash: Fe stars can no longer convert mass into energy via nuclear fusion ! • Nucleosynthesis up to Iron A massive star near the end of its lifetime has “onion ring” structure  T ~ 6*108 K  ~ 2*105 gcm-3 Carbon burning 12C +12C ->20Ne + 4He + 4.6 MeV 23Na + 1H + 2.2 MeV 20Ne +  ->16O + 4He 20Ne + 4He ->24Mg +  T ~ 1.5*109 K  ~ 107 gcm-3  Oxygen burning 16O + 16O ->28Si + 4He + 10 MeV 31P + 1H + 7.7 MeV

25. Nucleosynthesis beyond Iron WE BELIEVE THAT HALF of THE ELEMENTS BEYOND IRON ARE PRODUCED IN EXPLOSIONS of SUCH STARS SUPERNOVAE

26. 23 February 1987

28. We Saw Supernova 1987A on 23 February 1987. It Actually Happened 168,000 Light Years Ago It was 987,000,000,000,000,000 MILES Away ! 987 QUADRILLION MILES

29. Abundance of the Elements • Features: • 12 orders-of-magnitude span • H ~ 75% • He ~ 23% • C  U ~ 2% (“metals”) Almost 5 billion years ago, our solar system began the journey with its gravitation collapse… If we look around us today, we can see what elements were in our interstellar cloud…

30. Abundance of the Elements Data sources: Earth, Moon, meteorites, stellar (Sun) spectra, cosmic rays... Fe • Features: • 12 orders-of-magnitude span • H ~ 75% • He ~ 23% • C  U ~ 2% (“metals”) Au Abundance of elements and isotopes are UNIQUE finger prints of various cosmic processes. To interpret and understand them, diverse and vast nuclear physics knowledge is needed!!! Not fully solved!

31. U.S. Nuclear Science[Today and for the Next Decade] General goal: Explain the origin, evolution, and structure of the visible matter of the universe—the matter that makes up stars, planets, and human life itself.

32. The Science – Physics of Nuclei and Nuclear Astrophysics • What is the nature of the nuclear force that binds protons and neutrons into stable nuclei and rare isotopes? • What is the origin of simple patterns in complex nuclei? • What is the nature of neutron stars and dense nuclear matter? • What is the origin of the elements in the cosmos? • What are the nuclear reactions that drive stars and stellar explosions?

33. Nuclear Physics for Astrophysicsexperiments in laboratory to learn about nuclear reaction in stars • Two big problems in nuclear astrophysics: • - reactions in stars involve(d) radioactive nuclei  use RNB • - very small energies and very small cross sectionsindirect methods Measurement at lab energies Comparison with (reaction) calculations Extract (nuclear structure) information Compare with direct measurements Calculate nuclear reaction probability

34. My research highlights

35. Astrophysical motivation The first sources of light: Population III stars First stars about 400 million yrs.

36. G Black Hole G Collapse H pp-I,II,III G H CNO, rp Fate of Massive Pop III Stars 3a dynamic instability Tc 5  107 K crit  0.02 gcm-3 Explode

37. Hot pp chains and rap-process chains in low-metallicity objects M. Wiescher et al., 1989, Ap.J., 343 : Interest in 12N(p,)13O pp-I: p(p,e+)d(p,)3He(3He,2p)4He pp-II: 7Be(e-,)7Li(p,)4He pp-III: 7Be(p,)8B(+)8Be()4He pp-IV:7Be(p,)8B(p,)9C(+)9B(p)8Be()4He pp-V: 7Be(,)11C(+)11B(p,2)4He rap-I: 7Be(p,)8B(p,)9C(,p)12N(p,)13O(+)13N(p,)14O rap-II: 7Be(,)11C(p,)12N(p,)13O(+)13N)p,)14O rap-III: 7Be(,)11C(p,)12N(+)12C(p,)13N(p,)14O rap-IV: 7Be(,)11C(,p)14N(p,)15O • process material from pp cycles into CNO nuclei

38. (Faraday Cup) (Faraday Cup) Er - det . . 12 12 C C D D E E - - det det . (PSSD) . (PSSD) 12 12 N N Melamine target Melamine target Experimental Setup for 12N(p,)13O study via (12N,13O) proton transfer reaction

39. My research @ Madison Radiation Laboratory (JMU) • astrophysical motivation: • nucleosynthesis of heavy proton-rich elements beyond iron by • photoactivation technique using an electron linear accelerator Measurements of photoneutron reactions induced by activation of a target (stable nucleus), i. e. (,n) reaction rates High-resolution Germanium detectors Medical linac

40. LENA/TUNL TAMU HIS/TUNL RESOURCES: Existing facilities for research in Nuclear Astrophysics (North America) • Michigan State University/NSCL • Oak Ridge National Laboratory/HRIBF • Argonne National Laboratory/ATLAS • Lawrence Livermore National Laboratory/NIF • TRIUMF/ISAC (Canada) • University of Notre Dame/KN Van de Graaf accelerator • Yale University/WNSL • Florida State University/Super-FN tandem/RESOLUT

41. Overview of main astrophysical processes

42. Present and Future Direction inPhysics of Nuclei and Nuclear Astrophysics Rare Isotope Beams

43. Protons Neutrons RADIOACTIVE NUCLEI Producing radioactive nuclei Actually, made by nuclear reactions with stable nuclei: Long lived to very short lived isotopes can be produced and used to produce secondary reactions in laboratory

44. RIB Facilities (Operating or Under Construction)

45. FRIB-facility for rare isotope beams • Ions of all elements from protons to uranium accelerated “Where you could work” (after 2018)

46. What is the origin of the elements in the cosmos? s process r processsite unknown! p process FRIB reach • NAS report: “ConnectingQuarks with the cosmos” • 11 questions for the 21st century • how where the elements from iron to uranium made? protons Stellar burning Big Bang neutrons

47. In summary

48. Messages to take away… Nuclear reactions play a crucial role in the Universe: they provide the energy in stars including that of the Sun. they produced all the elements we depend on. nucleosynthesis is on-going process in our galaxy There are ~270 stable nuclei in the Universe. By studying reactions between them we have produced ~3000 more (unstable) nuclei. There are ~4000 more (unstable) nuclei which we know nothing about and which will hold many surprises and applications. Present techniques are unable to produce them in sufficient quantities. It will be the next generation of accelerators and the next generation of scientists (why not some of you?!) which will complete the work of this exciting research field.

49. Just As Your Parents Told You You Really Are Star Material !