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Introduction to Experimental Nuclear Astrophysics

2007 년 2 월 26-28 일 APCTP Workshop @ 포항. Introduction to Experimental Nuclear Astrophysics. 한인식 이화여자대학교. Outline. Introduction Nuclear Astrophysics Experimental considerations Selective experiments Nuclear reactions in the Sun Neutrinos from the Sun Explosive environment

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Introduction to Experimental Nuclear Astrophysics

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  1. 2007년 2월 26-28일APCTP Workshop @ 포항 Introduction to Experimental Nuclear Astrophysics 한인식 이화여자대학교

  2. Outline • Introduction • Nuclear Astrophysics • Experimental considerations • Selective experiments • Nuclear reactions in the Sun • Neutrinos from the Sun • Explosive environment • Nuclear reactions in supernovae • Nu-SNS Project • Conclusions

  3. Diff = 107

  4. Nuclear Astrophysics • Some of the most compelling questions in nature • How were the elements from iron to uranium made? • How does the sun shine for so many years? • What is the total density of matter in the universe? • How did the stars, galaxies evolve? • Require a considerable amount of nuclear physics information as input

  5. < Hoyle in 1953 > Is insufficient to explain the observed abundance Proposed O+ at 7.68 MeV in 1953 Measured at 7.65 MeV in 1957

  6. “It is a remarkable fact that humans, on the basis of experiments and measurements carried out in the lab, are able to understand the universe in the early stages of its evolution, even during the first three minutes of its existence.” Fowler (Nobel prize 1983)

  7. Nucleosynthesis in Cosmos 8 2 s p r o c e s s S t a b l e O b s e r v e d U n s t a b l e 5 0 r p p r o c e s s 1 2 6 S t e l l a r r p r o c e s s produce energy e v o l u t i o n 2 8 8 2 generate the elements 2 0 5 0 8 2 8 B i g B a n g 2 0 8 293 2,771 3,064 NNDC (BNL, 2000) Nuclearreactions in stars

  8. Nucleosynthetic reactions are typically dominated by Coulomb barriers

  9. Maxwell-Boltzmann distribution  exp(-E/kT) tunnelling through Coulomb barrier  exp(- ) Gamow peak relative probability E0 energy kT E0 Thermonuclear reactions in stars

  10. Nuclear Reactions in the Sun SOHO, 171A Fe emission line

  11. proton-proton chain proton-proton chain p + p  d + e+ + n p + d  3He + g 86% 14% 3He + 3He 4He + 2p 3He + 4He 7Be + g 99.7% 0.3% PP-I Qeff= 26.20 MeV 7Be + e- 7Li +n 7Be + p  8B + g 7Li + p  24He 8B 8Be + e+ +n PP-II Qeff= 25.66 MeV 24He PP-III Qeff= 19.17 MeV net result: 4p  4He + 2e+ + 2n + Qeff FromM. Aliotta

  12. From P. Parker @ Yale Univ.

  13. From P. Parker @ Yale Univ.

  14. http://wwwlapp.in2p3.fr/neutrinos

  15. FromSchatz@MSU First experimental detection of solar neutrinos: 1964 John Bahcall and Ray Davis have the idea to detect solar neutrinos using the reaction: • 1967Homestake experiment starts taking data • 100,000 Gallons of cleaning fluid in a tank 4850 feet underground • 37Ar extracted chemically every few months (single atoms !) and decay counted in counting station (35 days half-life) • event rate: ~1 neutrino capture per day ! • 1968First results: only 34% of predicted neutrino flux ! solar neutrino problem is born - for next 20 years no other detector ! Neutrino production in solar core ~ T25 nuclear energy source of sun directly and unambiguously confirmed solar models precise enough so that deficit points to serious problem

  16. Direct Coulomb dissociation ANC NaBoNA(Napoli Bochum Nuclear Astrophysics) FromL. Gialanella@ INFN

  17. Art Champagne for ENAM04

  18. Art Champagne for ENAM04

  19. Solar Neutrino Problem FUSIONREACTIONS p + p 2H + e+ + e p + e- + p  2H + e 2H + p 3He +  3He + 3He 4He + 2p 3He + p  + e+ +e 3He +  7Be +  7Be + e- 7Li +  +e 7Be + p 8B +  7Be + p   +  8B + 2  + e SOLAR NEUTRINO PROBLEM either Solar Models are Incomplete/incorrect or Neutrinos undergo flavor changing oscillation EXPERIMENTAL RESULTS Gallium flux = 57% SSM Chlorine flux = 34% SSM Super-K flux = 47% SSM From P. Doe, J. Wilkerson, H. Rebertson

  20. Sudbury Neutrino Observatory 1000 tonnes D2O Support Structure for 9500 PMTs, 60% coverage 12 m Diameter Acrylic Vessel 1700 tonnes Inner Shielding H2O 5300 tonnes Outer Shield H2O Urylon Liner and Radon Seal From P. Doe, J. Wilkerson, H. Rebertson

  21. The SNO Detector during Construction From P. Doe, J. Wilkerson, H. Rebertson

  22. Comparison of results

  23. The Nobel Prize in Physics 2002 "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos"

  24. Astrophysically Important Nuclear Reactions7Be(p,g)8B8Li(a,n)11B12C(a,g)16O14O(a,p)17F15O(a,g)19Ne17,18F(p,a)14,15O25Al(p,g)26Si44Ti(a,p)47V56Ni(p,g)57Cu85Kr(n,g)86Kr134Cs(n,g)135Cs…

  25. Experimental Nuclear Astrophysics produce energy generate the elements Nuclear reactions in stars Lab studies of reaction cross-sections

  26. A Better Set of Models for Explosive Events Hydrodynamic Properties Temperature Density Flow Etc.

  27. Requires a Better Understanding of Nuclear Processes Unstable Isotopes • Reaction rates • Excited states • Decay rates Bounds of Stability • Proton drip-line • Neutron drip-line Understanding Nucleosynthesis & Energy Generation in Explosive Events To study unstable isotopes we need radioactive beams!

  28. Supernova SimulationsFirst 300 ms: A. Burrows 300 km 10 km

  29. t = 0 Pb ○ SUPERNOVA R-PROCESS Otsuki, Tagoshi, Kajino & Wanajo 2000, ApJ 533, 424 Wanajo, Kajino, Mathews & Otsuki 2001, ApJ 554, 578 Z Fe ○ N t = 0 Neutrino-driven wind forms right after SN core collapse. n + p n + a t = 18 ms Seedsform. Exotic neutron-rich78Ni t = 568 ms – 1 s Heavy r-elements synthesize. Pb208 ○ Fe56 ○ Ni78 Pb ○ Fe ○

  30. M.S. Smith and K.E. Rehm, Ann. Rev. Nucl. Part. Sci, 51 (2001) 293 2,771 3,064 NNDC (BNL, 2000) In many cosmic phenomena, radioactive nuclei play an influential role, hence the need for Radioactive Ion Beams

  31. X-ray burst and novae

  32. 24Al 25Al Z rp process N 21Mg 22Mg 23Mg 24Mg 20Na 21Na 22Na 23Na 18Ne 19Ne 20Ne 21Ne 22Ne (a, g) 17F 18F 19F (a, g) (a, p) 14O 15O 16O 17O 18O 13N 14N 15N Stable 12C 13C HCNO cycle Unstable CNO cycle

  33. Measurements • Direct measurements are desirable ways to measure the 15O(a,g)19Ne and 14O(a,p)17F reactions over indirect methods. • Only became possible after new generation of accelerators that can make 14,15O and 17F beams in the late 90’s. • There are still large uncertainties of the reaction relevant to X-ray burst and novae.

  34. O

  35. OUTLOOK • Measurements using radioactive beams have given us a deeper understanding • Big Bang, the sun, novae, supernovae • More intense radioactive beams @ RIKEN, MSU, ANL, ORNL, RIA(future) • We expect to obtainmore experimental results of the important reactions that are relevant to both interesting stellar sites and big bang nucleosynthesis in the future.

  36. The Nu-SNS Project Ed Hungerford University of Houston

  37. SNS is the world’s brightest intermediate energy pulsed neutrino source SNS Particle Accelerators Nuclear Reactors Energy

  38. SNS neutrino spectra Supernova neutrino spectra, 100 ms post-bounce • n spectra from the SNS are JUST RIGHT, having significant overlap with the spectra of neutrinos generated in a supernova explosion! Right energy range • n spectra from nuclear reactors are TOO COLD! • n spectra from accelerators are TOO HOT! This gives us a unique opportunity to study neutrino interactions relevant to the region of interest for Supernova

  39. The Oak Ridge Spallation Neutron Source

  40. SNS Parameters • Primary proton beam energy - 1.3 GeV • Intensity - 9.6  1015 protons/sec • Number of protons on the target 0.687x1016 s-1 (1.1 ma) • Pulse duration - 380ns(FWHM) • Repetition rate - 60Hz • Total power – 1.4 MW • Liquid Mercury target • 0.13 neutrinos of each flavor produced by one proton (9 x 1014 s-1) • Number of neutrinos produced ~ 1.91022/year • There is a larger flux of ~MeV anti-neutrinos from radioactive decay • from the target

  41. Motivation for -SNS • Important Energy Window • Just right for supernovae studies • SN detector calibration • Almost no data • Extremely high neutrino flux • Potential for precision measurements • Can address a number of new • physics issues • Nuclear Physics processes • Can begin with small detectors

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