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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.

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Presentation on theme: "7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 21-26 AUGUST 2011 1 Nuclear Astrophysics Applications of Accelerators Alex."— Presentation transcript:

1 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST Nuclear Astrophysics Applications of Accelerators Alex Murphy These slides are online at https://files.me.com/alexsmurphy/3enros

2 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

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

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

5 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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...

6 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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?

7 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

8 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

9 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

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

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

12 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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!

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

14 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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 ]

15 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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!

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

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

18 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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.

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

20 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 2011

21 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

22 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 2011

23 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

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

25 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 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

26 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 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

27 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 2011 Data ASM et al. PRC 79 (2009) ✦ R-matrix analysis ✦ Deduce E,Γ   Γ   l, (interference)

28 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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) R

29 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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!

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

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

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

33 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 2011

34 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

35 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

36 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 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

37 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

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

39 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

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

41 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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 ~ /cm 3 ) ✦ Candidate sites: Supernovae or Neutron star mergers ObservableEffect SnPath T 1/2 Abundance pattern, timescale PnFreezeout abundance pattern ‘Cause and Effect’

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

43 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 2011

44 Predicted SuperFRS yields

45 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

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

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

48 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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

49 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, AUGUST 2011 Some particle astrophysics expts... Pierre Auger, 3000 km 2

50 7TH INTERNATIONAL SUMMER SCHOOL ON PARTICLE ACCELERATORS AND DETECTORS, BODRUM, 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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