1. Alex Murphy 1/2 Day IOP meeting on Supernovae 1 Alex Murphy http://www.ph.ed.ac.uk/nuclear/ http://hepwww.rl.ac.uk/ukdmc/ukdmc.html/ Experimental Nuclear Astrophysics Relevant to Supernovae

2. Alex Murphy 1/2 Day IOP meeting on Supernovae 2 Nuclear Astrophysics Interstellar gas Nuclear Reactions  Stellar stability Rise in T and  pp-chains CNO cycles s-process Thermonuclear runaway Triple  HCNO Breakout rp-process p-process r-process Explosive nucleosynthesis Gravitational collapse Formation of stars pp-chains

3. Alex Murphy 1/2 Day IOP meeting on Supernovae 3 Thermal energy distribution For ions – use MB statistics Novae: up to 2-3 x10 8 K X-ray bursts: up to 2-3 x10 9 K Supernovae: up to 10 10 K Nuclear Physics in Stars The rate at which reactions occur is determined by the overlap of the thermal energy distribution and nuclear cross sections Relevant energies 10keV - 10 MeV Cross sections Typically below Coulomb barrier Low cross sections Resonant processes dominate Low density of states Indirect methods can be useful  Need to know energies, spins, widths

4. Alex Murphy 1/2 Day IOP meeting on Supernovae 4 What we do and how we do it LOG SCALE  direct measurements EGEG E coul Coulomb barrier  (E) non-resonant resonance Astrophysical region E, J, ℓ tr, 

5. Alex Murphy 1/2 Day IOP meeting on Supernovae 5 Focus of recent research… Explosive astrophysical environments Novae, X-ray bursters, exotic scenarios Typically we have been concentrating on proton rich side, A<30 This is largely for technical reasons  (H)CNO cycles  Breakout from CNO processing  rp-processing…

6. Alex Murphy 1/2 Day IOP meeting on Supernovae 6 Example of what we do… Novae Masssive star (e.g. Red Giant) More massive star expands… Outer layers transferred to compact object movie Layer of H builds up on top of evolved material (e.g. C/O/…) Slow accretion rate leads to degeneracy Conditions for a thermonuclear runaway High temperatures and short timescales Ejecta Elemental composition Gamma ray emission…?

7. Alex Murphy 1/2 Day IOP meeting on Supernovae 7 Gamma-ray production in Novae Clayton & Hoyle Ap. J. 494 (1974) – direct observation of  -rays in novae ejecta Intensity of an observed  -ray flux would provide a strong constraint on novae modelling. Need to know the relevant reaction rates!  21 Na(p,  ) 22 Mg Nucleus  EmissionNova type 13 N862 s511 keVCO ONe 18 F158 m511 keVCO ONe 7 Be77 d478 keVCO 22 Na3.75 yr1275 keVONe 26 Al1.0x10 6 yr1809 keVONe INTEGRAL: launched Oct ’02 Nucleus  EmissionNova type 13 N862 s511 keVCO ONe 18 F158 m511 keVCO ONe 7 Be77 d478 keVCO 22 Na3.75 yr1275 keVONe 26 Al1.0x10 6 yr1809 keVONe

8. Alex Murphy 1/2 Day IOP meeting on Supernovae 8 Example: Novae Why is this reaction important? Synthesis of 22 Na in ONe novae  20 Ne(p,  ) 21 Na(p,  ) 22 Mg(  +) 22 Na or  20 Ne(p,  ) 21 Na(  +) 21 Ne(p,  ) 22 Na rp – process 20 Ne 21 Na 22 Mg 23 Al 24 Si 19 Ne 20 Na 22 Ne 23 Na 24 Mg 25 Al 26 Si 21 Ne 22 Na 23 Mg 24 Al 25 Si 25 Mg 26 Al 27 Si 26 Mg 27 Al 28 Si 19 F 18 F 17 F NeNa Cycle MgAl Cycle 18 Ne 22 Na Need to know (p,  ) rate compared to b- decay rate

9. Alex Murphy 1/2 Day IOP meeting on Supernovae 9 Experimental method TUDA DRAGON Radiative capture and elastic scattering studies (p,  ) (p,p) We use radioactive beam facilities such as those at TRIUMF and Louvain-la- Neuve

10. Alex Murphy 1/2 Day IOP meeting on Supernovae 10 192 strips, energy, angle and time of flight from each Resonant elastic scattering Primary beam: 20  A, 500 MeV, protons SiC primary target surface ion source Radioactive Beam 5x10 7 pps TUDA LEDA Target: 795  g/cm2 CH 2 foil

11. Alex Murphy 1/2 Day IOP meeting on Supernovae 11 Energy Time of Flight E (MeV)B.R. 5.7010.0016 5.2720.036 4.8940.193 4.6830.087 4.4382.94 3.8010.25 3.2100.03 2.14816.4 20 Na beam is radioactive!  alpha decays Elastically scattered protons 1 H( 20 Na, 1 H) 12 C( 20 Na, 12 C) 20 Na @ 32 MeV on 795  g/cm 2 CH 2, with 12.65  m Mylar Particle Identification

12. Alex Murphy 1/2 Day IOP meeting on Supernovae 12 Data… Three resonances observed Ex( 21 Mg) = 4.005MeVPrimary aim of the experiment. Tentative J  = (1/2 + )  3/2 + Ex( 21 Mg) = 4.26 MeVPreviously only E x known (no width, spin information) 5/2 + Ex( 21 Mg) = 4.44 MeV Previously unknown J  = 3/2 +

13. Alex Murphy 1/2 Day IOP meeting on Supernovae 13 Radiative Capture (p,  ) or ( ,  ) Use a Recoil mass separator + a gamma-ray array E.g. DRAGON: Detector of Recoils And Gammas of Nuclear Reactions Windowless gas target End detectors – silicon strip detector or ion chamber

14. Alex Murphy 1/2 Day IOP meeting on Supernovae 14 Measurement of 21 Na(p,  ) 22 Mg 21 Na beam on hydrogen target Varied 21 Na beam energy in small steps so as to scan resonances Detected recoils in coincidence with prompt gammas Determined resonance strengths for seven states in 22 Mg between 200 and 1103 keV

15. Alex Murphy 1/2 Day IOP meeting on Supernovae 15 Results – resonance strengths Yield curves for state at 206 keV (above) and at 821 keV (left) 22 Mg recoils in DSSSD E R =740 keV 22 Mg 21 Na

16. Alex Murphy 1/2 Day IOP meeting on Supernovae 16 Results: Reaction rate Results: The lowest measured state at 5.714 MeV (E cm = 206 keV) dominates for all novae temperatures and up to about 1.1 GK Updated nova models showed that 22 Na production occurs earlier than previously thought while the envelope is still hot and dense enough for the 22 Na to be destroyed  Results explain the low abundance of 22 Na

17. Alex Murphy 1/2 Day IOP meeting on Supernovae 17 What about observations…?  CGRO/COMPTEL – So far no detection; upper limits only.  But… consistent with current theory incorporating new reaction rate data.  Expectation…  INTEGRAL should see signal from nova < 1.1 kpc away  (~1 ONe nova per 5 yrs)  -ray emission from several close novae has been search for… Nova Her 1991

18. Alex Murphy 1/2 Day IOP meeting on Supernovae 18 Future directions: Around the world, facilities are advancing… ISAC-II (Canada), RIA (US), RIPS (Japan), Eurisol, REX-Isolde, SPIRAL-II, FAIR (Europe), More intense beams, more exotic beams, heavier beams Opportunities for detector development Now is the time to go after new physics!

19. Alex Murphy 1/2 Day IOP meeting on Supernovae 19 Future Directions An example relevant to type Ia supernovae

20. Alex Murphy 1/2 Day IOP meeting on Supernovae 20 SN Ia Scatter in brightness <0.3 mags, even without extinction correction (which is usually quite small). Over 90% have very reproducible light curves. Thus very useful as a standard candle Especially important in light of  CDM Non-standard SN Ia’s Effects that can change luminosity (e.g. metalicity) SN1991 D

21. Alex Murphy 1/2 Day IOP meeting on Supernovae 21 Recent ‘atypical’ observations: Recently, several atypical SNIa’s have been observed: SN 1987G - fast decline from maximum SN 1986G - anomalies in optical spectra SN 1990N - anomalies in optical spectra SN 1991T - 'largely deviated' from standard SN1991bg - dimmer than usual, some H detected. SN1999by - very similar to SN1991bg These differences suggest that maybe there really are two progenitor types...  He rich accretion on to sub-Chandrasekhar mass CO WDs may be responsible for the <10% of SNIa’s that have ‘peculiar’ light curves.

22. Alex Murphy 1/2 Day IOP meeting on Supernovae 22 Sub-Chandrasekhar mass models The existence of sub-luminous SN Ia’s interpreted as less than 1.4 M  56 Ni powering the light curve The Sub-Chandrasekhar mechanism: A 0.6 – 0.8 M  CO WD accretes He rich matter. 98% 4 He, 1% 12 C, 0.5% 14 N, 0.5% 16 O Existence (but not the exact quantity) of 14 N critical – a product of pop-I burning Moderate accretion rate (~10 -8 M  yr -1 )  He ignition at the CO/He interface. Competition between 14 N(e –, ) 14 C(  ) 18 O (‘NCO’) & Triple-  Ignition of He may strongly depend on rate of 14 C(  ) 18 O

23. Alex Murphy An indirect study of the 14 C(  ) 18 O reaction EEC Meeting, TRIUMF Alison Laird Jordi Jose LOI XXXV

24. Alex Murphy 1/2 Day IOP meeting on Supernovae 24 Future Directions An example relevant to Core Collapse supernovae

25. Alex Murphy 1/2 Day IOP meeting on Supernovae 25 Core Collapse Supernovae There is consensus on the basic mechanism And yet even the best simulations still don’t explode! Extremely complex Need a good diagnostic Produced in vicinity of mass cut Sensitive diagnostic of models Gamma-ray observable nuclide SN1987A M1 – The Crab 44 Ti!

26. Alex Murphy 1/2 Day IOP meeting on Supernovae 26 Core Collapse Massive star (>10–12 M  ) Stellar evolution  onion-skin-like structure At maximum of BE/A, thermal support lost  Core collapses After core-bounce, shock wave passes through Si layer above core Dissociation back to n, p, and  …Nuclear statistical equilibrium… …Alpha-rich freeze out Dominant site for 44 Ti production Key reactions to be studied* 40 Ca(  ) 44 Ti(  ) 44 Ti( ,p) 45 V(p,  ) Triple  * (The et al ApJ 504 (1998) 500) EPSRC Grant

27. Alex Murphy 1/2 Day IOP meeting on Supernovae 27 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 What’s more, it’s (relatively) easily observed Gamma-Ray observation 1.157 MeV INTEGRAL & other missions Meteoritic data Enrichment of 44 Ca in type X presolar grains Timmes et al. (1996) Wilson. (1985)

28. Alex Murphy 1/2 Day IOP meeting on Supernovae 28 Pretty pictures… A grain from the Murchison Meteorite Integral GLAST

29. Alex Murphy 1/2 Day IOP meeting on Supernovae 29 Summary Nuclear reactions are the power behind most astrophysical phenomena Astrophysical models require accurate nuclear physics inputs New facilities (and upgrades) mean we can now start looking at reactions important in new environments Nuclear Astrophysicists need good guidance!

30. Alex Murphy 1/2 Day IOP meeting on Supernovae 30 The End Thank you

31. Alex Murphy 1/2 Day IOP meeting on Supernovae 31 Spare slides

32. Alex Murphy 1/2 Day IOP meeting on Supernovae 32 Latest development… Proposed research requires: Low energy 44 Ti and 45 V beams Refractory elements are hard to extract from ‘standard’ ion sources A new approach… Exotic Radionuclides from Irradiated MAterials for Science and Technology PSI is looking at reducing the amount of radioactive waste it has produced Potential users: Nuclear Medicine Geophysics Astrophysics … Could bleed these ions into a non-RNB ion source and re-accelerate them LLN? Triumf? Other? Proposal in to EU FP7 programme

33. Alex Murphy 1/2 Day IOP meeting on Supernovae 33 LEDA 795  g/cm 2 CH 2 1.25 MeV/u 1.60 MeV/u High sensitivity Faraday cup Recoil proton 9.55 or 12.40  m Mylar 5.65 or 9.65  m Mylar 19.5 cm 60.5 cm 4.6 o <  lab < 31.2 o Typical set-up (from 20 Na(p,p) expt) 20 Na 3.50 < E x ( 21 Mg) < 4.64 MeV

34. Alex Murphy 1/2 Day IOP meeting on Supernovae 34 Astrophysical significance: NeMg Novae Temperatures achieved are too low for breakout NeNa and MgAl cycles thought to provide necessary energy production. NeNa cycle: First stage is 20 Ne(p,  ) 21 Na. Where does the 20 Ne come from?  -decay of 20 Na feeds 20 Ne. Rate of 20 Na(p,  ) compared to the  + decay of 20 Na (448ms) determines abundance of 20 Ne 20 Ne 19 Ne 21 Na 22 Na 20 Na 23 Mg 21 Mg 22 Mg 23 Na NeNa cycle 21 Ne

35. Alex Murphy 1/2 Day IOP meeting on Supernovae 35 An understanding of the cosmos Observations Modelling Nuclear Astrophysics …

36. Alex Murphy 1/2 Day IOP meeting on Supernovae 36 Novae and X-ray Bursters… Binary systems! Compact, evolved star (white dwarf or neutron star) orbiting a massive star (e.g. Red Giant) More massive star expands… Outer layers transferred to compact object Layer of H builds up on top of evolved material (e.g. C/O/…) Slow accretion rate leads to degeneracy Conditions for a thermonuclear runaway High temperatures and short timescales  Radioactive nuclei important

37. Alex Murphy 1/2 Day IOP meeting on Supernovae 37 Novae White dwarf with companion star Temperatures of up to 3 x 10 8 K Time: 100-1000s to eject layer Light curve increases to max in hours but can take decades to decline Absolute magnitude can increase by up to 11 magnitudes Can be recurrent Ejecta Elemental composition Gamma ray emission…? Nova Herculis 1934: AAT

38. Alex Murphy 1/2 Day IOP meeting on Supernovae 38 Some recent measurements… p( 20 Na,p)Indirect study of 20 Na(p,  ) 21 Mg reaction X-ray bursters: a crucial link in the rp-process Novae: affects NeNa cycle. p( 21 Na,p)Indirect study of 21 Na(p,  ) 22 Mg reaction Novae: Potential for satellite gamma ray observations p( 11 C,p)Indirect study of 11 C(p,  ) 12 N reaction High mass stars/Novae: 18 Ne( ,p)Direct study. Breakout from HCNO cycle: Catalyst for rp-process?

39. Alex Murphy 1/2 Day IOP meeting on Supernovae 39 20 Na(p,p) 20 Na Motivation Better knowledge of the level structure of 21 Mg is needed… Astrophysics Nucleosynthesis and energy generation X-ray bursts Novae Reaction rates dominated by resonant contributions Nuclear Physics Proton-rich nuclei far from stability, Large level shifts, Comparison of reaction mechanisms, Shell model studies The Experiment Resonant elastic scattering: 20 Na(p,p) 20 Na (inverse kinematics, using TUDA at TRIUMF)

40. Alex Murphy 1/2 Day IOP meeting on Supernovae 40 Astrophysical significance: X-ray Bursters T ~ 4 x 10 8 K Energy generation by HCNO cycles Waiting points at 14 O, 15 O and 18 Ne isotopes 12 C 13 C 13 N 14 N 15 O 16 O 17 F 18 F 18 Ne 15 N 17 O 14 O 15 O 16 O 17 F 18 F 18 Ne 17 O 14 O 15 O 16 O 17 F 18 F 18 Ne 19 Ne 21 Na 22 Na 20 Na 23 Mg 21 Mg 22 Mg 17 O 14 O T  6 x 10 8 K ( ,p) and (p,  ) rates overtake   decays Reaction flow dominated by 15 O( ,  ) 19 Ne(p,  ) 20 Na(p,  ) 21 Na … ‘Breakout’ into rp-process begins Triggers subsequent explosion

41. Alex Murphy 1/2 Day IOP meeting on Supernovae 41 The run: Successful experiment ran at TRIUMF 5 days of stable 20 Ne calibration beams 7 days of radioactive 20 Na beams: up to 5x10 7 pps. Thick target method: Scan through region of excitation in 21 Mg to look for resonances Detect proton recoils Expect Rutherford + resonances (+ interference). Resonance depends on E x,  p, J, and l tr Two–body kinematics For a selected angle  energy of detected protons reflect the energy the reaction occurred at. Hence, proton energy spectrum is just an excitation function.

42. Alex Murphy 1/2 Day IOP meeting on Supernovae 42 Calibrations etc Standard triple alpha source Pulser walk-through…

43. Alex Murphy 1/2 Day IOP meeting on Supernovae 43 Analysis of proton data Gate on protons… Project out energy spectrum… Subtract alpha background… R-matrix analysis… General formalism – Lane & Thomas Inverse level matrix approach Based on earlier coding separately developed by Lothar Buchman and by Dick Azuma Present version courtesy of C. Ruiz. ½ integer spin, multi-channel, non-zero l tr, …

44. Alex Murphy 1/2 Day IOP meeting on Supernovae 44 X-ray Bursters… Similar environment to novae, but replace white dwarf with a neutron star. Much deeper gravitational potential Hotter, denser, faster Less accreted material/smaller surface area  lower luminosity than novae Temperatures up to ~2-3 x 10 9 K Time: 1-10s to lift degeneracy and eject layer Ejecta? little net ejecta due to gravitational field X-ray burster in NGC 6624: HST HEAO light curve of X-ray burst MXB 1728-34

45. Alex Murphy 1/2 Day IOP meeting on Supernovae 45 Simulations Helium burning at base of He layer Occurs around  =10 6 g/cc Competition between 14 N(e –, ) 14 C(  ) 18 O (‘NCO’) & Triple-  Nucleosynthesis (extended network codes : Goriely et al. A & A 388 2002) Possible site for generating p-process nuclides. Expanding outward shock wave  T 9 =2 – 3 Material ejected Mo and Ru isotopes produced Such explosions produce 44 Ti (contrary to standard SN1a)  Ignition of He may strongly depend on rate of 14 C(  ) 18 O See also: Hoflich, Khokhlov & Wheeler [1995], Goriely, Jose, Hernanz, Rayet and Arnould [2002]

46. Alex Murphy 1/2 Day IOP meeting on Supernovae 46 The 14 C(  ) reaction rate: Effect This reaction rate is undetermined, with an uncertainty factor 100 Model ‘A’ – Standard reaction rateStandard reaction rate Model ‘B’ – Standard reaction rate x 100 Model ‘C’ – Standard reaction rate  100 Model B Shorter accretion duration Less mass accreted Less 56 Ni in explosion Ignition density  =1.77x10 6 g/cc  Less violent explosion Peak (at base of He layer) T 9 = 2.77 Model c Longer accretion duration More mass accreted More 56 Ni in explosion Ignition density  =3.92x10 6 g/cc  More violent explosion Peak T 9 (at base of He layer) = 3.22

47. Alex Murphy 1/2 Day IOP meeting on Supernovae 47

48. Alex Murphy 1/2 Day IOP meeting on Supernovae 48 Direct capture 3 – state at 177 keV Current knowledge of reaction rate Reaction rate See Buchmann, D’Auria & McCorquodale (1998), Funck & Langanke (1989), Görres et al. (1992) Direct capture component (T<3x10 7 K) 177 keV resonant component remains undetermined. Dominates rate 0.03 < T 9 < 0.2  State of interest:  E r =177 keV (6.404 MeV in 18 O), J  =3 –  No direct measurements  No spectroscopic factor  Not calculated in theoretical studies (e.g. Descouvemont & Baye 1985)  Proximity to  -threshold  Resonance strength determined by    small branching ratio (~10 -10 )  Indirect methods must be used  6 Li( 14 C,d) 18 O, 12 C( 14 C, 8 Be) 18 O, 7 Li( 14 C,t) 18 O… Funck & Langanke (1989)

49. Alex Murphy 1/2 Day IOP meeting on Supernovae 49 14 C(  ) 18 O Experimental details Experimental issues  Can 14 C be separated from 14 N?  5x10 7 pps for 1 week not likely to be a radiological safety hazard Rate of FC <1000 Bq:  range ~3 cm (in air)  6 Li( 14 C,d) 18 O – kinematics drive 2 H from different states very close together. Would require very thin (10  g/cm 2 ) targets Target contamination (C/O/F)  12 C( 14 C, 8 Be) 18 O  Identify 8 Be from 2 alphas E rel =92 keV  Coulomb Barrier…

50. Alex Murphy 1/2 Day IOP meeting on Supernovae 50 Spectroscopic factor Compare angular distribution to reaction model to get spectroscopic factor. Alpha transfer below Coulomb barrier Need spectroscopic factor measured in transfer reaction    Must be careful of model uncertainties FRESCO, ZAFRA Calibration reaction? Compound nucleus contribution HF & Angular distribution…

51. Alex Murphy 1/2 Day IOP meeting on Supernovae 51 Summary There are several reasons to believe that He rich accretion on to sub-Chandrasekhar mass CO WD SN occur. They are astrophysically very interesting They are ‘consistent’ with sub-luminous SNIa Proposed as a site for p-processing Evolution is likely to depend on the currently unknown reaction rate of 14 C(  ) 18 O Direct measurement unfeasible Indirect methods: 14 C( 6 Li,d), 14 C( 12 C, 8 Be) Need to develop a 14 C beam

52. Alex Murphy 1/2 Day IOP meeting on Supernovae 52 Example: Type Ia Supernovae For dark energy

53. Alex Murphy 1/2 Day IOP meeting on Supernovae 53 Kinematics 12 C( 14 C, 8 Be) 18 O 6 Li( 14 C,d) 18 O  cm vs  Lab E lab vs  Lab

54. Alex Murphy 1/2 Day IOP meeting on Supernovae 54 States in 18 O 14 C+  6.227 18 O 6.4043–3– 6.198 6.880 7117 1–1– 6.3512–2– 4+4+ 1–1– 0.177 State populated strongly in (t,p):  tot ~0.4 mb (Cobern et al. PRC 23 (1981) 2387) Somewhat weaker in ( 7 li,p) (d,p), (t,  ), ( 6 Li,d), ES: little strength Gamma decay to multiple states.

55. Alex Murphy 1/2 Day IOP meeting on Supernovae 55 Proposed research Take advantage of unique future ISAC beams 44 Ti( ,p) 47 V – direct measurement Gas/implanted target Trilis, CSB LEDA/CD Not measured before at astrophysical energies - extrapolation of previous results suggests it’s eminently feasible (@ 10^7 pps). 45 V(p,p) 45 V – resonant elastic scattering Knowledge of 46 Cr, precursor to 45 V(p,  ) 46 Cr Trilis, CSB CH 2 target LEDA/CD Unmeasured. SM/TES suggests ‘feasible’ (@ 10^7 pps). 45 V(p,  ) 46 Cr Trilis, CSB DRAGON Use (p,p) as guide. Coordinated approach

56. Alex Murphy 1/2 Day IOP meeting on Supernovae 56 UK Grant application A request has been made to EPSRC specifically focussed on this work Request was for 33 months of PDRA salary + Travel Panel met 27/7/05 …funded! Advertising now Deadline 16/09/05 Can start 1/11/05