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Nuclear Astrophysics Applications of Accelerators

Nuclear Astrophysics Applications of Accelerators. Alex Murphy ( a.s.murphy@ed.ac.uk ). These slides are online at https://files.me.com/alexsmurphy/3enros. 1. 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011. Additional material!.

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Nuclear Astrophysics Applications of Accelerators

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  1. Nuclear Astrophysics Applications of Accelerators Alex Murphy (a.s.murphy@ed.ac.uk) These slides are online at https://files.me.com/alexsmurphy/3enros 1 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  2. Additional material! • I have written 6 questions, based on the material in this talk. • One is to be used in your EXAM! • ...There are also solutions (“Phew!”) • I hope these questions allow you to think about the material further • Questions (and solutions) will be made available by the organisers These slides are online at https://files.me.com/alexsmurphy/3enros 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  3. Motivation 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  4. Stellarium: tonight 10pm. 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  5. What are the stars? • Hertzsprung Russell diagram • Clearly shows that there are several distinct categories of star • What more can we know of them? • What is the “physics”? • Start with their source of power... 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  6. A simple calculation... Our Sun. • We receive ~1.38 kW/m2 at the Earth’s surface • Distance to the Sun: 1.5x1011 m • ➔ total luminosity = 3.9x1026 W • Mass of Sun = 2x1030 kg • Coal outputs ~35 kJ/kg+ • ➔ If the Sun is chemically burning, then it’s <5.5 years old. ✘ • p-p chain: 0.7% mass converted to energy • ~1011 years supply* ✔ + is this typical? *but not all the sun burns 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  7. Atomic Fraction Atomic Fraction Mass Fraction Mass Fraction What is the Universe is made of...? Look at the Sun, the stars, distant Galaxies... >99% of matter is Hydrogen or Helium 7 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  8. Chemical evolution • However, variations in A>4 chemical abundances are seen in various types of stellar object • There appears to be a universal ‘primordial’ abundance • Older stars - less O, Fe • Novae - enhancements in C, N, O, Ne... • Supernovae - ‘scaled’ solar abundance (esp. for high masses) • Meteorites - certain abundance ratios show strong deviations from solar/terrestrial material • Gamma rays indicate recent nucleosynthesis • 26Al (halflife 7.4x105 yrs) seen in interstellar medium • 44Ti (halflife 59 yrs) seen in supernova remnant Stars are the furnaces of chemical elements 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  9. A few examples... 14N/15N 12C/13C X - SNe origin Y,Z, Mainstream - AGB stars A+B grains - Source unknown Scaled solar abundances match r-process; indicates ‘primary process’ 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  10. Novae 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  11. Abundances linked to Nuclear Physics • Odd-even stagger • Peaks correspond to magic numbers • Suggests nuclear physics as key to understanding abundances of the elements 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  12. Astrophysical processes Alpher-Bethe-Gamow, Phys. Rev. 73 (1948) 803 • Broad mechanisms now understood • Various processes occur in the different stellar sites depending on the the particular environment (F (T, P, Z, τ, Rot, B...)) • BBN • p-p chains • CNO cycles • rp-process • α-process • r-process • s-process • p-processes • NSE... All still actively researched! 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  13. Stellar energies 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  14. Thermonuclear Reaction Energies • Typical environment temperatures: • Our Sun: ~15x106 K kT ~ 1 keV • Novae: ~4x108 K kT ~ 35 keV • BBN, Supernovae: ~1010 K kT ~ 2 MeV • The rate of nuclear reactions is determined by the cross section and the energies of the particles in the reaction • Cross sections increase with energy (penetration through Coulomb barrier) • Temperatures described by Maxwell Boltzmann Energies are relatively LOW [cm3 mole-1 s-1] 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  15. Reaction rates Gamow peak and window • Indicates the energy region where nuclear physics is likely to be important • Typically ~ a few × kT • Cross sections for quiescent burning scenarios ≲pb • Cross sections for explosive scenarios ≳ μb ←Very difficult! ←Difficult! Most nuclear astrophysics (to date) explores explosive scenarios Shorter timescales, by definition, means radioactive nuclei become important Low energy radioactive ion beams often desirable 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  16. Example: BBN 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  17. Big bang nucleosynthesis 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  18. An example of a BBN experiment... • Explore a reaction that might impact results... • Production of 6Li (to compare to some recent observations) • Sputter source generates 7Li beam: VdG ~ 20 MeV • 8Li beam produced with 9Be(7Li,8Li)8Be: ~10-15 MeV; ~105 pps • 2 mg/cm2 CD2 experimental target foil • 4He and 6He ions detected in silicon arrays. 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  19. Example: Novae 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  20. 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  21. Novae • Classical Novae • accretion of H on CO or ONe WD • Temp’ and densityincrease; ‘flash’ • Our understanding to date is based on… • Light curves • Spectra • Meteoritic data • Problems… • Limited information in light curves • Spectra give chemical abundances • Spectra give ~final abundances • Meteoritic data also is ‘delayed’ & complex • A better probe would be gamma-rays Artist’s conception Chandra observation 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  22. 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  23. Gamma ray probes of Novae Overall novae gamma-ray emission is dominated by 511 keV γ-rays from 18F β+ decay • Need to know rates of reactions creating and destroying 18F • Large Uncertainties remain, especially in 18F(p,α)15O • Rate is determined by resonant contributions from states in 19Ne M Hernanz, JINA 2005 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  24. ISOL Technique TRIUMF • 500 MeV proton driver • SiC, Ta, UCx targets • Re-acceleration in RF cavities, DTL, SC LINAC... • ISAC-I: 0.25-1.6 MeV/A • A~<40 • ISAC-II: 1.5-6.5 MeV/A • Any A • TUDA • DRAGON • TIGRESS • SHARC • (EMMA) • Others 18F has halflife of 110 minutes : RIB necessary 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  25. 18F(p,α)15O at TUDA 18F9+ beam 1.6 MeV/A 105 pps 2mm beamspot, ~1ns wide bunches 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  26. Typical data 18F(β) 12C(18F,12C) 1H(18F,1H) Fusion-Evaporation protons Linearised Time of Flight Energy α contamination in the chamber 1H(18F,α) 12C(18F,12C) 26 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  27. Data • R-matrix analysis • Deduce E,Γp, Γα, l, (interference) ASM et al. PRC 79 (2009) 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  28. Recent direct data PRC 82 (2011) 042801R • A direct thin target measurement of the 18F(p,α) reaction at • 250, 330, 453 & 673 keV 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  29. Effect of Coulomb barrier Clare Beer, Thesis, 2010 ~1 hour at Ecm=673 keV ~3 hours at Ecm=453 keV ~1 day at Ecm=330 keV ~1 week at Ecm=250 keV Rate at low energies (Gamow window) is very low Backgrounds become critical! 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  30. Context of 1 reaction rate! Slide: Anuj Parikh 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  31. Example (proposed): Supernova 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  32. Text 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  33. 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  34. The CCSN Neutrino Mechanism • Massive star (>8–10 M) • Stellar evolution  onion-skin-like structure • At maximum of BE/A, thermal support lost  Collapse • Huge flux of neutrinos “re-energises” explosion • Neutrino driven wind – an excellent candidate site for the r-process The main source of 44Ti is thought to be from deep within CC supernova 7 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  35. Astrophysical Gamma Ray Emitters 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  36. 44Ti production as a diagnostic • Amount ejected sensitively depends on location of the ‘mass cut’ • Material that ‘falls back’ is not available for detection • 44Ti yield a sensitive diagnostic of the explosion mechanism • Thus, very useful for models to make comparisons against Wilson. (1985) 44Ti(α,p) is the key reaction Timmes et al. (1996) 12 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  37. The ERAWAST Project • Would like to measure 44Ti(α,p) reaction directly. • 44Ti target difficult (half-life ~59 yr) • 44Ti RIB difficult • What about feeding 44Ti into a ‘stable’ ion source? • Obtain 44Ti from activated material, e.g. copper beam dump Many other uses for this technology 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  38. ERAWAST workshop 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  39. The S and R processes STRONG WEAK • Consider isotopes sitting in a neutron ‘bath’. Very short lived Short lived Long lived beta decay Stable (n,γ) Z N The R(apid) Process The S(low) Process 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  40. Example: The R-process 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  41. The r-process • Produces the heavy elements • Rapid neutron capture • Rapid compared to beta-decay (τn<<τβ, τn~μs) • Requires very high flux of neutrons (Φn~1024-1030/cm3) • Candidate sites: Supernovae or Neutron star mergers ‘Cause and Effect’ 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  42. GSI... and FAIR The biggest development ever in European Nuclear Physics? Nuclear astrophysics was a lead driver of the science case! 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  43. 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  44. Predicted SuperFRS yields 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  45. Major new instrumentation needed • Aim to look at beta-delayed decays shortly after implantation • High rate; huge energy mis-match; demanding resolution 8cm x 8cm wafers; 0.5 mm position resolution Novel spectroscopic ASIC readout 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  46. AIDA prototyping 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  47. Finally... something a bit different... 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  48. ‘Another’ nuclear astrophysics • Which was the first accelerator...? • Which accelerator has the highest energies...? • Which accelerator has the most intense flux...? • Nature! • Access to new physics • Access to new, more exotic astrophysical environments 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  49. Pierre Auger, 3000 km2 Some particle astrophysics expts... 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

  50. SUMMARY • When you next look at the stars... I hope you spend a moment thinking about what they are! • The study of nuclear astrophysics covers a diverse range of phenomena • Nuclear astrophysics experiments use many different accelerator technologies, ranging from the small ‘in-house’ Van de Graaff to the major new facilities such as FAIR • No one technology will provide all the answers • Only the tip of the ice berg has been covered here! Thank you 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011

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