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Experimental nuclear astrophysics: studying the stars in the laboratory

Explore the research activities of Atomki's nuclear astrophysics group, including low cross-section measurements, p-process experiments, electron screening effect studies, and more. Utilize facilities such as the K20 cyclotron and Van de Graaff accelerator for research in ion beam analysis, atomic physics, and solid state physics.

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Experimental nuclear astrophysics: studying the stars in the laboratory

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  1. Experimental nuclear astrophysics: studying the stars in the laboratory György Gyürky Institute of Nuclear Research (Atomki) Debrecen, Hungary Szilárd Leó Colloquium, BME, 10 October 2017

  2. Research topics: Experimental and theoretical nuclear physics Atomic physics Ion beam analysis Environmental science Solid state physics etc… Main facilities: K20 cyclotron 1 MV and 5MV Van de Graaff (new) Tandetron Accelerator Mass Spectrometry Microprobe Target laboratory ECR ion source Electron spectrometer SIMS/SNMS surface analysis device Radiochemistry lab … Research at ATOMKI http://www.atomki.hu

  3. Research activities of the nuclear astrophysics group of ATOMKI Underground experiments: low cross section measurements (LUNA collaboration) Experiments for the astrophysical p-process Study of the electron screening effect Half-life measurements relevant to astrophysics RIB experiments relevant to astrophysics 7Be isotope production for nuclear astrophysics experiment Application of the Trojan Horse indirect method etc...

  4. sunrise sunset A nap belsejében Energy generationof stars • Nuclear reactions • Main sequence stars: hydrogen burning • Conversion of 4 protons into one 4He • pp-chain(s) Inside the Sun

  5. pp-chains of hydrogen burning

  6. The original sin: stars have time Sun A supernova ~ 1 billion K ~100 keV  < 10-9 barn ~ 1 s • 15 million K • 1.3 keV (Coulomb barrier: 550 keV) •  << 10-12 barn • 10 billion years

  7. Relevant energies in nuclear astrophysics tunneling probability Maxwell-Boltzmann distribution

  8. Danger of extrapolation Raw experimental data K.W. McVoy et al., Nucl. Phys. A542 (1992) 295

  9. Danger of extrapolation Theoretical model

  10. Danger of extrapolation Extrapolation

  11. Danger of extrapolation Different parameters

  12. Danger of extrapolation Different theoretical description

  13. Astrophysical example: 3He + 3He 4He +2p

  14. ? Astrophysical S-factor • Barrier penetration  steeply (exponentially) dropping cross section • S-factor: smoother energy dependence • Contains nuclear physics • Easier to extrapolate S(E) = E·(E)·exp(2) 2 = 31.29 Z1 Z2 (/E)0.5

  15. Astrophysical example: 3He + 3He 4He +2p 5 orders of magnitude !!!

  16. Experimental difficulties • Low cross section  low count rate • High intensity beams • Long measurements • Background reduction • Cosmic rays are difficult to avoid  let’s go underground

  17. " Some people are so crazy that they actually venture into deep mines to observe the stars in the sky ". (Naturalis Historia - Plinio, 23-79 ad) LUNA: watching the stars from the deep Laboratori Nazionali del Gran Sasso 1400 m depth LUNA collaboration: Laboratory for Underground Nuclear Astrophysics

  18. Firts measurements directly at solar energies LUNA 1998 1 event in 2 weeks!!!

  19. 23Na(p,)24Mg LUNA experiments1992-2017 17O(p,)18F 14N(p,)15O 7Be(p,)8B 25Mg(p,)26Al d(,)6Li 3He(,)7Be 22Ne(p,)23Na 3He(d,p)4He 15N(p,)16O 17O(p,)14N d(p,)3He

  20. One of the most recent LUNA results 17O(p,)14N cross section measurement „A long-standing puzzle on the origin of stardust recovered from meteorites has finally been solved thanks to the better understanding of nuclear reactions happening in stars producing such dust grains.”

  21. Big bang, H, He, (7Li) Stellar burning stages, C-Fe Heavy elements: s-, r-, p-processes, Fe-U Cosmic ray, Li, Be, B “Composition” of the Universe Fe-Ni

  22. Synthesis of heavy elements r-process s-process p-process

  23. p-process Proton number r-process Neutron number Zr Y Sr (n,g) Rb p-isotopes Kr Br (b-) Se As (b+) Ge Ga Zn r-isotopes Cu Ni Co Fe

  24. 74Se 78Kr 84Sr 92Nb 92,94Mo 96,98Ru 102Pd 106,108Cd 113In 112,114Sn 120Te 124,126Xe 130,132Ba 138La 136,138Ce 144,146Sm 156,158Dy 162Er 168Yb 174Hf 180Ta 180W 184Os 190Pt 196Hg 10 2 10 2 10 1 10 0 10 1 10 -1 10 0 10 -2 10 -3 10 - 1 10 -4 10 - 2 10 -5 abundance (Si = 106) 10 - 3 s s - - process process 10 - 4 r r - - process process 10 - - 5 p p - - process process 80 100 120 140 1 80 100 120 140 1 60 180 200 60 180 200 mass number mass number p-nuclei (p-nuts): the unknown Universe mainly even-even nuclei 0.1-1% isotopic abundance

  25. Secondary process Gamma-induced /mainly (,n)/ reactions on s- and r-process seed isotopes (-process) High temperature needed: supernova explosions The synthesis of p-isotopes 108Sn 109Sn 110Sn 111Sn 112Sn 113Sn 114Sn 115Sn 116Sn (,p) (,) (,p) 108Cd 106Cd (,n) 25

  26. Courtesy: S. Goriely

  27. p-process reaction network ~ 2000 isotopes ~ 20000 reactions Mainly (,n), (,), (,p) reaction and beta decays The models are not able to reproduce the observed p-isotope abundances I. Dillmann et al., J. Phys. G 35 (2008) 014029 Mo 27

  28. Contradicting theory, no experiment

  29. Alpha-induced reactions: 5-15 MeV  Cyclotron Proton-induced reactions: 1-4 MeV  Tandetron, (Van de Graaff) ERC Starting Grant „Nuclear reaction studies relevant to the astrophysical p-process nucleosynthesis” Experiments in Debrecen

  30. Testing theoretical calculations

  31. Direct influence on p-process networks (,n) (,n) (,n) 108Sn 110Sn 112Sn 114Sn (,) (,) (,) (,p) (,p) (,p) (,n) (,n) (,n) 106Cd 108Cd 110Cd old Main reaction path based on the reaction rates new secondary paths T = 2.0·109 K

  32. Outlook 1: Racing with astronomers CNO cycle • Solar composition problem: contradiction between • Helioseismology (high precision) • Solar model, supported by neutrino detection (high precision) 14N(p,)15O More precise reaction cross sections needed!

  33. Outlook 2: Studying unstable nuclei • Many astrophysical processes involve short-lived radioactive nuclei • Radioactive Ion Beam facilities needed

  34. Thank you for your attention!

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