Nuclear Physics for Astrophysics: from the Laboratory to the Stars

Transcription

1 Nuclear Physics for Astrophysics: from the Laboratory to the Stars Livius Trache IFIN-HH Bucuresti-Magurele & Cyclotron Institute, Texas A&M University Texas 2013 Symposium, Dallas, TX, Dec 9-13, 2013

2 Summary 1. A few contributions of nuclear physics to astrophysics and cosmology Source of stars light Origin of elements 2. Examples Big Bang Nucleosynthesis Confirmation thru BBNucleosynthesis First determination of Baryon/photon ratio Number of neutrino types Number of quarks Solar neutrino puzzle 3. Indirect methods in NPA with RIBs Nuclear breakup Beta-delayed proton decay 4. Some future

3 Nuclei and Nuclear Astrophysics in XX c. Edington nuclear reactions at the origin of stars energy Astronomy becomes astrophysics; Hubble; desc of galaxies 1930s Bethe CNO cycle and the pp chain; the neutron 1948 abg primordial reactor (Apr 1, 1948: Alpher, Bethe and Gamow in Phys. Rev.). The amazing legacy of a wrong paper (M. Turner) is the beginning of precision cosmology 1957: B 2 FH paper (Burbidge, Burbidge, Fowler and Hoyle) and Cameron (Chalk River): BBN and stellar nucleosynthesis 60s-70s: solar neutrinos detected and solar neutrino puzzle (Pontecorvo, Alvarez R. Davis Jr., started 1948, Nobel prize 2002) SM and The first three minutes We, the epigones! Models Hydrodynamics Nuclear data 3

4 2 Nuclear astrophysics Nuclear astrophysics increasingly motivation for NP research: Nuclei are the fuel of the stars Origin of chemical elements: nucleosynthesis = a large series of nuclear reactions & elemental/isotopic abundances are indelible fingerprints of cosmic processes Big successes of NA: BBN quantitative, first determination of baryon/photon ratio, or parameter free (after CMB) nr. of neutrino types=3 Heavier elements created in stars Solar reactions understood (pp-chains, CNO, solar neutrinos ) Nucleosynthesis is on-going process! (quasi-) understand novae, XRB, neutron stars, but not super-novae

5 H 73% He 24% Solar system abundances (A.G.W. Cameron, 1982) Fe peak reflect nuclear properties and stellar environment(s) note odd-even staggering and abundance peaks: Not an equilibrium process!

6 -(UNDERGROUND LABORATORY) Use of laboratory with natural shield ( underground physics-for instance LUNA experiment at LNGS-Italy ) 2 H(p,g) 3 He GRAN SASSO Stars are cold! GANOW ENERGY

7 NPA: thousands of reactions Direct meas: difficult, stars are cold! Indirect methods: Coulomb dissociation One-nucleon transfer reactions Breakup reactions Spectroscopy of resonances Trojan Horse Method Tests models and param M. Smith & E. Rehm mass, T 1/2 resonances + fission barriers?! site, path?! mass, T 1/2 Two big problems: 1. - reactions in stars involve(d) radioactive nuclei use RNB 2. - very small energies and very small cross sections indirect methods 7

8 3a Breakup (one-nucleon removal r.) Momentum distributions nlj Cross section ANC (only!!!) Gamma rays config mixing Need: V p-target & V core-target and reaction mechanism Calc: F. Carstoiu (Bucharest); Data: see later 8

9 Example: 7 Be(p,g) 8 B Solar neutrino problem 4 1 H 4 He+2e + +2n p-p chain reaction pp III chain (0.01%) The figures are adapted from J. N. Bahcall, Neutrinos from the Sun 16-Dec-13 9

10 Example: Summary of the ANC extracted from 8 B breakup with different interactions Data from: F. Negoita et al, Phys Rev C 54, 1787 (1996) B. Blank et al, Nucl Phys A624, 242 (1997) D. Cortina-Gil e a, EuroPhys J. 10A, 49 (2001). R. E. Warner et al. BAPS 47, 59 (2002). J. Enders e.a., Phys Rev C 67, (2003) All available breakup cross sections on targets from C to Pb and energies MeV/u give consistent ANC values! Summary of results: LT ea, PRL 87, 2001 LT ea, PRC 67, different effective nucleon-nucleon interactions slightly different values 7 Be(p,g) & accuracy 8 B (solar to neutrinos about 10% : probl.): p-transfer: JLM (blue S squares), 17 (0)=18.2±1.7 evb Breakup: standard S 17 (0)=18.7±1.9 m=1.5 fm (black evb points) Direct Ray meas: (red triangles). S 17 (0)=20.8±1.4 evb 10

11 Astrophysical motivations The first sources of light: Population III stars novae T 9 ~ GK X-ray Bursts First stars about 400 million yrs. T 9 ~ 1-2 GK ANC - transfer ANC nuclear breakup

12 GANIL E491 exp 54 MeV/n 12 C( 22 Mg, 22 Na) 12 N Charge exchange (new & unexpected) 23 Al 22 Mg+p Proton removal (sought) 12

13 Complementarities: Coulomb and nuclear dissociation Similar results from mirror system: 22 Ne+n-> 23 Ne 13 C( 22 Ne, 23 Ne) 12 C assuming S n =S p [46] T. Gomi, T. Motobayashi et al, JPG 31 (2005) 13

14 Energy 3b 5/2 + Decay spectroscopy 23 Al Resonant Capture a two-step process Selection rules Coulomb Barrier E c G p G g E p p Radius S p Conditions: Q EC >S p +2m e c 2 J=3/2+, 5/2+, 7/2+ 23 Mg Nuclear Potential g+ 23 Mg 23 Mg * 22 Na+p 5/2 +, 7/ / Same compound system: 23 Mg Resonance strength Resonant contributions to reaction rate: E 1 GG p g g=(2j+1)/(2j+1)(2i+1)b 2 1 2J t 1 G g b p *G tot 32 Lower 2 proton energies most 2 important, g r but very difficult: g res r = exp mkt kt lower branching J p increased exp difficulties (det windows, background, etc ) Need energy, J r and resonance strength 14

15 Decay spectroscopy Beta- and beta-delayed proton-decay Explosive H-burning in novae & IAS in T z =-3/2 nuclei Isospin mixing GT strength distribution 22 Na depletion in novae 23 Al 23 Mg* 22 Na(p,g) 23 Mg* & 22 Mg(p,g) 23 Al bottleneck r. in novae 31 Cl 31 S* 30 P(p,g) 31 S* 15

16 23 Al MARS In-flight RB production 24 Mg 48A MeV 23 Al 40A MeV Purity: 90%, or >99% after en degrader Intensity: ~ 4000 pps First time - very pure & intense 23 Al (p,2n) reaction Primary beam 24 48A MeV K500 Cycl Primary target LN 2 cooled H 2 gas p=1.6-2 atm Secondary beam A MeV 16

17 b decay study of pure RB samples 17

18 Full disclosure! Background subtracted using decay of 22 Mg (not a proton emitter) 18

19 Solution: ASTROBOX emitted proton electrons E Pollacco (CEA Saclay) proposed: Gas detector w MICROMEGAS Low proton energies (~1-200 kev), good resolution (5-10%) Reduced b background 19

20 kev 234 IAS?! Run0311B: 23 Al bp-decay with ASTROBOX Implantation control Off-beam spectrum Center detector Outer + center 20

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22 4 Extreme Light Infrastructure 2006 ELI on ESFRI Roadmap ELI-PP (FP7) ELI-Beamlines (Czech Republic) ELI-Attoseconds (Hungary) ELI-Nuclear Physics (Romania) Project Approved by the European Competitiveness Council (December 2009) ELI-DC (Delivery Consortium): April 2010 Bucharest: June 2013 civil constr started 22

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24 Nuclear Astrophysics - Indirect methods 1. with RIBs: Steps at ELI-NP RNB production: mechanism study production w. spectrometer(s), w. gas-filled separator?! RNB separation momentum achromat + velocity filter?! Secondary beam preparation Filters?! Reacceleration?! Secondary reaction target station Detection complex array(s): gas, Si, g, PID, position sensitive, Extract NS information - difficult theory calc: structure and reactions (Normalization) - may need absolute values from elsewhere NA interpretation - theory support again! Comparison with direct measurements/ normalization develop strong program of direct measurements at the 3 MV tandetron L. Trache, ELI-NP workshop, Bucharest, June 25-26,

25 2. Laser-induced stellar plasma?! Short-lived plasmas w conditions similar to stellar plasmas?! Characterization Nuclear astrophysics: capture reactions on excited states very imp for quantitative descr of stellar nucleosynthesis, but out of the range of our current experimental possibilities. Can we?!! How?! What setups?! CETAL 1 PW laser to work in 2014, in Bucharest!!! 25 L. Trache, ELI-NP workshop, Bucharest, June 25-26, 2013

26 Thank you!