ASTROFÍSICA NUCLEAR (EXPERIMENTAL)

Transcription

1 ASTROFÍSICA NUCLEAR (EXPERIMENTAL) Visión general y algunos ejemplos César Domingo Pardo

2 Outline Introducción X-ray bursts: rp-process Heavy elements nucleosynthesis: the slow (s-) and the rapid (r-) neutron capture processes R-process in core collapse supernovae: experiments with radioactive ion beams S-process in massive stars: neutron capture measurements

3 Outline Introducción X-ray bursts: rp-process Heavy elements nucleosynthesis: the slow (s-) and the rapid (r-) neutron capture processes R-process in core collapse supernovae: experiments with radioactive ion beams S-process in massive stars: neutron capture measurements

4 The context of (experimental) nuclear astrophysics LHC Standard Model

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6 número de neutrones en el núcleo número de protones en el núcleo

7 En química: Estructura atómica (e- valencia) Reacciones químicas + =

8 En astrofísica: Estructura nuclear Reacciones nucleares (NUCLEOSÍNTESIS) Energy 3/ 2 CM 2π 2 ( ER, i ) < συ >= ( ωγ ) i exp µ kt h i kt La estructura cuántica del núcleo determina la tasa de producción (nucleosíntesis) estelar La estructura nuclear determina las reacciones nucleares que pueden dar lugar a nuevos isótopos, nuevos núcleos, nuevos elementos.

9 How to bring x-ray bursts to the lab?

10 How to bring x-ray bursts to the lab? RIB Facility 3/ 2 Radioactive ion of interest (proton rich) (see Alejandro s talk) CM 2π 2 ( ER, i ) < συ >= ( ωγ ) i exp µ kt h i kt γ-ray Detectors LUCRECIA AGATA

11 To learn more Bibliography: H. Schatz et al., Phys. Rev. Lett. 86, 3471 (2001) Published 16 April 2001, End Point of the rp Process on Accreting Neutron Stars A.Parikh, et al., The effects of variations in nuclear interactions on nucleosynthesis in thermonuclear supernovae, Astronomy & Astrophysics, Volume 557, id.a3, 11 pp DOI: / / A. Parikh, et al., Nucleosynthesis in type I X-ray bursts, Progress in Particle and Nuclear Physics, Volume 69, p (2013) Nature 302, (24 March 1983); doi: /302317a0 Sub-second pulsations simultaneously observed at microwaves and hard X rays in a solar burst The JINA center for the evolution of the elements: Schools: 3rd Astrophysical Nuclear Reaction Network School

12 The context of (experimental) nuclear astrophysics

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14 just after Big-Bang

15 The context of (experimental) nuclear astrophysics

16 Nucleosynthesis of the light-to-medium heavy nuclei (up to Fe) Hydrostatic evolution stages of massive stars Iron group elements are built in the last burning phase before SN explosion 25 M Massive stars 8 M < M < 70 M M = 1.989x10 30 Kg Beyond the Fe-group, no further fusion reactions (charged particles) are possible

17 after first (massive) stars evolved

18 What kind of reactions could originate the heaviest nuclei? BB Fusion H He C O Fe Ge Sr Te Ba Pt Pb

19 What kind of reactions could originate the heaviest nuclei? Neutrons produce 75% of all the elements 0.005% of the total abundances (!) orders-of-magnitude difference between H and the rarest (heaviest) nuclei (!) BB Fusion Neutrons H He C O Fe Ge Sr Te Ba Pt Pb

20 What kind of reactions could originate the heaviest nuclei? Neutrons produce 75% of all the elements 0.005% of the total abundances (!) orders-of-magnitude difference between H and the rarest (heaviest) nuclei (!) BB Fusion Neutrons H He C O Fe explosive stellar environments, SNe, NS-NS, red giants Ge Sr Te Ba Pt Pb

21 El origen de los elementos pesados: procesos s y r s-process r-process core He-burning shell C-burning SN,N-StarStar Mergers, etc? K ~ K kt=26 kev kt=91 kev 10 6 cm cm Ne( 4 He,n) 25 Mg massive stars > 8 M Where is the site? How is the environment? Entropy Rotation, 3D, etc

22 The rapid (r-) neutron capture process Several candidates: SNe, NS-Mergers, NS-BH Mergers, etc High entropy and neutron density conditions required T = K N n = cm -3 _ ν - e + n p + e ν e + p n + e + Argast et al., 2004

23 R-process r-process nucleosynthesis nuclear physics input: the Pt-peak known t 1/2 HOT COLD _ ν e + n p + e - ν e + p n + e + (γ,n) (n, γ) NucNet network code, B. Meyer et al., Clemson University FRDM+QRPA (P. Möller) + JINA Reaclib Database (Cyburt)

24 R-process nucleosynthesis: relevant nuclear input known t 1/2 Beta-decays tailor the final abundance pattern How well do we know such β-decays?

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26 How to bring Supernovae to the lab? RIB Facility Radioactive ion of interest (neutron rich) (see Alejandro s talk)

27 How to bring Supernovae to the lab? 1 1,, + = N Z N Q MZMβ RIB Facility Radioactive ion of interest (neutron rich) (see Alejandro s talk) + = β β Q E N z N Z i i Ei R Z f E S T 0 1 1,, 2 1/ ),, ( ) ( 1 MM + + = β β β β Q E N z N Z i Q E S N z N Z i n i i n Ei R Z f E S Ei R Z f E S P 0 1 1,, 1 1,, ),, ( ) ( ),, ( ) ( MMMM( ) = 0 2 3/, ) / exp( ) ( 8 de kt E E E kt v N Z σ π σ M

28 How to bring Supernovae to the lab? 1 1,, + = N Z N Z Q MMβ RIB Facility Radioactive ion of interest (neutron rich) (see Alejandro s talk) + = β β Q E N z N Z i i Ei R Z f E S T 0 1 1,, 2 1/ ),, ( ) ( 1 MM + + = β β β β Q E N z N Z i Q E S N z N Z i n i i n Ei R Z f E S Ei R Z f E S P 0 1 1,, 1 1,, ),, ( ) ( ),, ( ) ( MMMM( ) = 0 2 3/, ) / exp( ) ( 8 de kt E E E kt v N Z σ π σ M

29 Principle of TOF Mass Measurements momentum analysis p=mv Bρ start L stop B ρ = m q v v = L t L = const Bρ = const m q = const t production target

30 time-domain (oscilloscope): Timing Detector Fourier analysis (frequency domain): Detector f1 f2 1 ( m / q) 1 ( m / q) = 2 f γ m / q - 2 t

31 stable isotopes r -process path β-decay path Pt Ir Os Re W Ta Hf Lu Yb Tm Er Au Hg Tl Pb S n = M Z,N M Z,N-1 = 2-3 MeV Bi one/two neutron emission r-process path Po neutron number 126 Stellar Nucleosynthesis (A 200) At

32 First observation of Te in metal poor stars (!!) I. Roederer et al., The Astroph. Journ. Lett Connection with RIKEN

33 Other (weaker) neutron sources in the universe: red giants

34 Two different s-process sites Main s-process 90<A<210 Weak s-process A<90 TP-AGB stars 1-3 M shell H-burning He-flash K K kt=8 kev kt=23 kev cm cm C( 4 He,n) 16 O 22 Ne( 4 He,n) 25 Mg massive stars > 8 M core He-burning shell C-burning K ~ K kt=26 kev kt=91 kev 10 6 cm cm Ne( 4 He,n) 25 Mg

35 The s-process mechanism φ n small s process in Massive Stars (Red Giants) λ β >> λ n,γ,γ τ β << τ n,γ La, Ba s process Pb, Bi core He-burning shell C-burning K ~ K kt=25 kev kt=90 kev 10 6 cm cm Ne( 4 He,n) 25 Mg = A Z(n,γ) A+1 Z (n,γ) Cross Sections

36 How to bring AGB and Massive Stars to the lab? Neutron beam facility with neutron energies similar to the stellar envionment Sample of the isotope of interest (stable or radioactive)

37 CERN n_tof facility C. Rubbia et al., A high resolution spallation driven facility at the CERN-PS to measure neutron cross sections in the interval from 1 ev to 250 MeV, CERN/LHC/98-02(EET) 1998.

38 CERN n_tof facility n_tof 200 m Tunnel Sample Pb Spallation Target Proton Beam 20GeV/c 7x10 12 ppp Booster 1.4 GeV Neutron Beam 10 o prod. angle Linac 50 MeV PS 20GeV

39 (n,γ) Cross sections via prompt γ-ray(s) detection BaF 2 Total Absorption Calorimeter (TAC) n (Z,A) (Z,A+1) + C 6 D 6 based Total Energy Detector (TED) César Domingo-Pardo

40 (n,γ) Cross sections via prompt γ-ray(s) detection BaF 2 Total Absorption Calorimeter (TAC) n (Z,A) (Z,A+1) + C 6 D 6 based Total Energy Detector (TED) César Domingo-Pardo

41 Example: Temperature in TP AGB Stars TP-AGB stars 1-3 M shell H-burning He-flash K K kt=8 kev kt=23 kev cm cm C( 4 He,n) 16 O 22 Ne( 4 He,n) 25 Mg

42 Temperature in TP AGB Stars How hot is the stellar environment where s-process nucleosynthesis takes place? λ β (T) 152 Gd 153 Gd 154 Gd 155 Gd 156 Gd 157 Gd 151 Eu 152 Eu 153 Eu 154 Eu 155 Eu 156 Eu 150 Sm 151 Sm 93 a 152 Sm 153 Sm 154 Sm f β = ( < σ γ > ( < σ > γ N N s s ) ) 151Sm 152 Gd λβ ( T ) = 151Sm 154Gd λβ vt nn < σ γ > 151Sm N s,152gd & N s,154gd

43 Temperature in TP AGB Stars How hot is the stellar environment where s-process nucleosynthesis takes place? λ β (T) 152 Gd 153 Gd 154 Gd 155 Gd 156 Gd 157 Gd 151 Eu 152 Eu 153 Eu 154 Eu 155 Eu 156 Eu 150 Sm 151 Sm 93 a 152 Sm 153 Sm 154 Sm f β = ( < σ ( < σ γ γ > > N N s s ) ) 151Sm 152 Gd λβ ( T ) = 151Sm 154Gd λβ vt nn < σ γ > 151Sm Just measure <σ γ > 151Sm N s,152gd First challenge: & 151 N s,154gd Sm does not exist in Earth!!!

44 Temperature in TP AGB Stars ILL Grenoble Φ n = 1.5x10 15 n/cm 2 /s few grams of 150 Sm 150 Sm 151 Sm 93 a

45 Temperature in TP AGB Stars MACS-30 = 3100 ± 160 mb T He = x10 8 K T H = 1x10 8 K 152 Gd 153 Gd 154 Gd 155 Gd 156 Gd 157 Gd 151 Eu 152 Eu 153 Eu 154 Eu 155 Eu 156 Eu 150 Sm 151 Sm 93 a 152 Sm 153 Sm 154 Sm U Abbondanno et al. Phys. Rev. Lett. 93 (2004), S. Marrone et al. Phys. Rev. C 73 (2006) 03604

46 Last slide: links to learn more JINA-CEE youtube seminar series: nucleosynthesis topics, theory, observations and experiments WEBNUCLEO (B. Meyer s blog and code): nuclosynthesis network code + examples to learn MESA (Modules for Experiments in Stellar Astrophysics) NuGRID: NuPECC:Nuclear Physics European Collaboration Committee