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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 1 Nuclear Astrophysics Applications of Accelerators Alex Murphy (a.s.murphy@ed.ac.uk)a.s.murphy@ed.ac.uk These slides are online at https://files.me.com/alexsmurphy/3enros
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 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
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Motivation
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Stellarium: tonight 10pm.
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 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...
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 A simple calculation... Our Sun. ✦ We receive ~1.38 kW/m 2 at the Earth’s surface ✦ Distance to the Sun: 1.5x10 11 m ✦ ➔ total luminosity = 3.9x10 26 W ✦ Mass of Sun = 2x10 30 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 ✦ ~10 11 years supply* ✔ *but not all the sun burns + is this typical?
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 What is the Universe is made of...? 7 Atomic Fraction Mass Fraction Atomic Fraction Mass Fraction Look at the Sun, the stars, distant Galaxies... >99% of matter is Hydrogen or Helium
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 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 ✦ 26 Al (halflife 7.4x10 5 yrs) seen in interstellar medium ✦ 44 Ti (halflife 59 yrs) seen in supernova remnant Stars are the furnaces of chemical elements
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 A few examples... Scaled solar abundances match r- process; indicates ‘primary process’ 14 N/ 15 N 12 C/ 13 C X - SNe origin Y,Z, Mainstream - AGB stars A+B grains - Source unknown
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Novae
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Abundances linked to Nuclear Physics ✦ Odd-even stagger ✦ Peaks correspond to magic numbers ✦ Suggests nuclear physics as key to understanding abundances of the elements
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Astrophysical processes ✦ Broad mechanisms now understood ✦ Various processes occur in the different stellar sites depending on the the particular environment (F (T, P, Z, , Rot, B...) ) ✦ BBN ✦ p-p chains ✦ CNO cycles ✦ rp-process ✦ -process ✦ r-process ✦ s-process ✦ p-processes ✦ NSE... Alpher-Bethe-Gamow, Phys. Rev. 73 (1948) 803 All still actively researched!
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Stellar energies
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Thermonuclear Reaction Energies ✦ Typical environment temperatures: ✦ Our Sun: ~15x10 6 K kT ~ 1 keV ✦ Novae: ~4x10 8 K kT ~ 35 keV ✦ BBN, Supernovae: ~10 10 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 [cm 3 mole -1 s -1 ]
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 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 ≳ Most nuclear astrophysics (to date) explores explosive scenarios Shorter timescales, by definition, means radioactive nuclei become important Low energy radioactive ion beams often desirable ←Difficult! ←Very difficult!
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Example: BBN
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Big bang nucleosynthesis
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 An example of a BBN experiment... ✦ Explore a reaction that might impact results... ✦ Production of 6 Li (to compare to some recent observations) ✦ Sputter source generates 7 Li beam: VdG ~ 20 MeV ✦ 8 Li beam produced with 9 Be( 7 Li, 8 Li) 8 Be: ~10-15 MeV; ~10 5 pps ✦ 2 mg/cm 2 CD 2 experimental target foil ✦ 4 He and 6 He ions detected in silicon arrays.
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Example: Novae
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011
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Novae Classical Novae accretion of H on CO or ONe WD Temp’ and density increase; ‘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
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011
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Gamma ray probes of Novae Overall novae gamma-ray emission is dominated by 511 keV -rays from 18 F + decay Need to know rates of reactions creating and destroying 18 F Large Uncertainties remain, especially in 18 F(p, ) 15 O Rate is determined by resonant contributions from states in 19 Ne M Hernanz, JINA 2005
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 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 18 F has halflife of 110 minutes : RIB necessary
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 18 F(p,) 15 O at TUDA 18 F(p, ) 15 O at TUDA 18 F 9+ beam 1.6 MeV/A 10 5 pps 2mm beamspot, ~1ns wide bunches
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 26 Typical data Energy Linearised Time of Flight 1 H( 18 F, 1 H) 1 H( 18 F, ) 12 C( 18 F, 12 C) Fusion-Evaporation protons 18 F( ) contamination in the chamber
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Data ASM et al. PRC 79 (2009) ✦ R-matrix analysis ✦ Deduce E,Γ Γ l, (interference)
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Recent direct data A direct thin target measurement of the 18 F(p, ) reaction at 250, 330, 453 & 673 keV PRC 82 (2011) 042801R
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Effect of Coulomb barrier Clare Beer, Thesis, 2010 ~1 hour at E cm =673 keV ~3 hours at E cm =453 keV ~1 day at E cm =330 keV ~1 week at E cm =250 keV Rate at low energies (Gamow window) is very low Backgrounds become critical!
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Context of 1 reaction rate! Slide: Anuj Parikh
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Example (proposed): Supernova
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Text
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011
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7 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 44 Ti is thought to be from deep within CC supernova
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Astrophysical Gamma Ray Emitters NucleuslifetimeEmissionSource 13 B862 s511 keVCO Novae ONe Novae 18 F158 m511 keVCO Novae ONe Novae 7 Be77 d478 keVCO Novae 22 Na3.75 yr1275 keVONe Novae 26 Al1.0 Myr1809 keVWR, CC SNe? 44 Ti87 yr1157 keVCC SNe 60 Fe2.2 Myr1173,1333 keVCC SNe
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 12 44 Ti production as a diagnostic Amount ejected sensitively depends on location of the ‘mass cut’ Material that ‘falls back’ is not available for detection 44 Ti yield a sensitive diagnostic of the explosion mechanism Thus, very useful for models to make comparisons against Timmes et al. (1996) Wilson. (1985) 44 Ti( ,p) is the key reaction
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 The ERAWAST Project Would like to measure 44 Ti( , p) reaction directly. 44 Ti target difficult (half-life ~59 yr) 44 Ti RIB difficult What about feeding 44 Ti into a ‘stable’ ion source? Obtain 44 Ti from activated material, e.g. copper beam dump Many other uses for this technology
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 ERAWAST workshop
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 The S and R processes ✦ Consider isotopes sitting in a neutron ‘bath’. WEAK The S(low) Process STRONG The R(apid) Process Z N Stable Long lived Short lived Very short lived (n, ) beta decay
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Example: The R-process
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 The r-process ✦ Produces the heavy elements ✦ Rapid neutron capture ✦ Rapid compared to beta-decay ( n << n ~ s) ✦ Requires very high flux of neutrons ( n ~10 24 -10 30 /cm 3 ) ✦ Candidate sites: Supernovae or Neutron star mergers ObservableEffect SnPath T 1/2 Abundance pattern, timescale PnFreezeout abundance pattern ‘Cause and Effect’
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 GSI... and FAIR The biggest development ever in European Nuclear Physics? Nuclear astrophysics was a lead driver of the science case!
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011
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Predicted SuperFRS yields
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 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
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 AIDA prototyping
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Finally... something a bit different...
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 ‘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
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 Some particle astrophysics expts... Pierre Auger, 3000 km 2
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7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 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
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