1. Nuclear Laboratory Data Needs for Astrophysics S. E. Woosley, Alex Heger, and Rob Hoffman with help from Tuguldur Sukhbold, Justin Brown, Michael Wiescher, Thomas Janka, and Roland Diehl John Poole and S. Woosley (1983)

2. "There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact." Mark Twain and Willy Fowler on many occasions

3. Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality. - Nikola Tesla

4. NUCLEAR ASTROPHYSICS Requirements for nuclear data are very broad and diverse We want to understand the origin of every isotope (fortunately not every isotope interacts with every other one!) Three general areas of application: Nucleosynthesis – Big Bang, Stars, Novae, Supernovae, Cosmic Rays Energy Generation – Stars, Sun (including neutrinos), Novae, X-Ray Bursts Behavior of matter at high density and temperature

5. PROBLEMS PARTICULAR TO NUCLEAR ASTROPHYSICS The relevant energies in the stars are generally much lower than what can be accessed in the laboratory Both product and target nuclei are frequently radioactive ( t decay > t HD ) Targets exist in a thermal distribution of excited states There are a lot of nuclei and reactions (tens of thousands)

6. Typical nuclear data deck for stellar nucleosynthesis includes 5442 nuclei and 105,000 reactions (plus their inverses). Fortunately not all are equally important. Most (non-r-process) studies use about 1/3 of this.

7. SOURCES OF DATA Theory Hauser-Feshbach R-Matrix analysis Direct capture calculations Weak interactions as f(T, r ) Laboratory Stable targets – (underground), low background, high current Unstable beams – e.g., FAIR/GSI, ISAC/TRIUMF, RIBF/RIKEN, ISOLDE/CERN, ATLAS/ARGONNE, NSCL/MSU, FRIB (to come) Surrogate reactions, inverse reactions, THM, etc. … and tabulations of all data in a refereed machine usable format –

8. Rate distributions (a partial list): https://groups.nscl.msu.edu/jina/reaclib/db/ Cyburt et al ApJS 189, 240 (2010) Univ California rate set http://www.astro.ulb.ac.be/bruslib/ Xu et al (2012) astroph1212.0628 http://adg.llnl.gov/Research/RRSN/ The Brussels (NACRE2) rate set The KADONIS (Karlsruhe) rate set for s- and p-processes The JINA rate set http://www.kadonis.org Portal to many collections (ORNL) http://www.nucastrodata.org/datasets.html … and many more

9. Yields averaged over a Salpeter ( G = 1.35) initial mass function. Responsible for producing the elements 4 < Z < 39

10. Isotopic yields for 31 stars averaged over a Salpeter IMF, G = -1.35 Intermediate mass elements (23< A < 60) and s-process (A = 60 – 90) well produced. Carbon and Oxygen over- produced. p-process deficient by a factor of ~4 for A > 130 and absent for A < 130

11. Lately, we have been testing the JINA rate distributions in stellar and supernova models against our older collection of rates. Four masses of stars 15, 18, 22, and 25 solar masses. Hold structure constant, i.e., use same rates for energy generation, but use new rates for nucleosynthesis. Used JINA 1.0, version 2.0 in progress (many bugs found in JINA 1.0)

12. Results using new rates Results using old rates

13. ~fac 2 changes (mostly down) for many ( ag ) and ( a,p) reactions on Ca and Ti 31 P being destroyed by larger 31 P(p, a ) 28 Si rate

15. Slight overall increase in s-process (even though 22 Ne( a,n) 25 Mg went up by 20%) due to factor of 4 decrease in 22 Ne (a,g ) 26 Mg

16. New data includes revised partition functions, Q-values, weak decay rates and dozens of reaction rates. No very large changes (> factor 2) found yet for A < 100 nucleosynthesis but study continues. Larger changes expected for r-process and rp-process synthesis. Switching to JINA 2.0 now. Abundance determinations in the sun and meteorites is now giving agreement to 10% for most elements. Commensurate accuracy in the stellar models and nuclear physics desired Studies like this will help locate regions of uncertainty.

17. SOME SPECIFIC CURRENT CHALLENGES 1) 12 C( a,g ) 16 O (and 3a) – Probably the last remaining uncertain reactions that affect stellar structure as well as nucleosynthesis 2) 22 Ne( a,n) 25 Mg - Main source of neutrons for the s-process. Important diagnostic for which stars actually blow up 3) Reactions affecting the production of 26 Al, 44 Ti, and 60 Fe. Important long lived radioactive gamma-ray line emitters 4)Reactions affecting the rp-process in x-ray bursts and the r-process of nucleosynthesis (nuclei far from stability) 5)Reactions affecting the solar neutrino flux or Big Bang nucleosynthesis

18. 12 C ( a, g ) 16 O Oxygen-16 Low energy data are needed to improve reliability of cross section extrapolation The relative rates of 3 a and 12 C( a,g ) 1 6O determine the proportions of C and O that come out of helium burning. C and O are fuels for major subsequent burning stages. *

19. uncertainty Heger, Woosley, & Boyse (2002) Obviously 12 C (a,g ) 16 O affects the nucleosynthesis 12 C and 16 O, but it also directly affects the production of many other species made by carbon, neon and oxygen burning. Many species are successfully coproduced if the rate has an S-factor at 300 keV of about 170 keV b But it also affects the structure of the pre- supernova star

20. Density Profiles of Supernova Progenitor Cores 2D SASI-aided, Neutrino-Driven Explosion? These should be easy to explode These will be hard to explode. High binding energy. High prompt accretion rate.

21. O’Connor and Ott, ApJ, 730, 70, (2011) Characterize possibility of a neutrino-powered explosion based upon the compactness parameter, z, If R is small and the 2.5 solar mass point lies close in, then z is big. The star is hard to explode. Based upon a series of 1D models OO11 find stars with z over 0.45 are particularly difficult to explode. Ugliano et al, ApJ, 757, 69 (2012) find more diversity and get explosions for a smaller value of x, as low as 0.15

22. Density Profiles of Supernova Progenitor Cores 2D SASI-aided, Neutrino-Driven Explosion? Large z Small z

23. Convective Carbon Core Burning (exoergic ) Strong carbon Burning Shell Easier to explode Sukhbold and Woosley (in prep) Harder to explode Oconnor and Ott (2011) ~Ugliano et al (2012)

24. Island of Explodability ? Stars with very litle mass loss e.g., low metallicity stars

25. (Thomas Janka, PTEP, 2012) Shock radius as a function of time for 2D simulations by Janka’s group. All stars but the 25 solar mass model explode – at least initially. This includes 27 solar masses

26. norm. Buchmann (1996) S(300 keV) = 146 keV b The mass of the maximum mass star that has exoergic carbon core burning as a function of the 12 C( a,g ) 16 O rate. The most likely range of the multiplier here is 0.85 to 1.3 (S(300 keV) = 159 +- 20% keV b). That implies an uncertainty in the mass of 3 to 4 solar masses. (calculations by Sukhbold)

28. Current situation (S(300 keV)): Buchmann (1996) 146 keV b (range 82 – 270) Buchmann (2005) 145 +- 43 keV b Kunz et al (2001) 165 +- 50 keV b Schuermann (2012) 161+- 16 +8-2 (sys) keV b We use 1.2 * Buchmann = 175 keV b (and have used it for 15 years) 12 C ( a, g ) 16 O

29. In progress deBoer et al. R-matrix analysis of ~10,000 experimental data points. Success so far for 15 N(p, g ) and 15 N(p, a ) Expected accuracy < 10% (Wiescher private communication ) 12 C( a,g ), 12 C( a,p), 12 C( a,a ), 15 N(p, g ), 15 N(p, a ), 15 N(p,p), and 16 N( b - a ) including all the various gamma, alpha, and proton decay channels.

30. Low Energy References

31. High Energy References

32. Of equal importance to 12 C( a,g ) 16 O is 3 a The current uncertainty in 3 a is 10%, i.e., beginning to be comparable to the uncertainty in 12 C( a,g ) 16 O. Error in one rate compromises the accuracy of the other West, Heger, and Austin (2013 in press) astroph 1212.5513

33. West, Heger, and Austin (2013) 3 a uncertainty dominated by pair width of 0 + resonance

34. 22 Ne( a,n) 25 Mg and the Heaviest Supernova

36. 14 N (a,g ) 18 O( a,g ) 22 Ne( a,n) 25 Mg 22 Ne burns at the very end of helium burning. If it does not burn to completion or if it burns by 22 Ne( a,g ) 26 Mg, then the neutrons are released later in carbon burning when there are abundant neutron poisons like 23 Na. The s-process is thus stronger in stars that reach higher temperature in helium burning, i.e., in more massive stars. The production of the s-process relative to 16 O thus depends on the mass of the star. Only the most massive stars make it.

37. Smartt, 2009 ARAA Progenitors heavier than 20 solar masses excluded at the 95% condidence level. Presupernova stars – Type IIp and II-L The solid line is for a Salpeter IMF with a maximum mass of 16.5 solar masses. The dashed line is a Salpeter IMF with a maximum of 35 solar masses

38. LOW

39. Brown and Woosley (2013, submitted)

41. 22 Ne (a,g ) 26 Mg 22 Ne( a,n) 25 Mg Longland, Iliadis, and Karakis (PRC, 2012) norm hi x 2

42. Radioactivities Detected by their Gamma-Ray Lines RadioactivityLifetimeDetectedProduced 44 Ti89 y 87A, Cas A, Tycho? Explosive Si burning 26 Al1.04 x 10 6 ISM Explosive Ne burning 60 Fe3.8 x 10 6 ISM Explosive He burning

43. Reactions affecting 44 Ti ( a -rich freeze out) Relevant temperature range T 9 = 2 - 4

45. 40 Ca( a,g) 44 Ti Nassar (2006) Vockenhuber (2008) Hoffman et al (2010) Robertson et al (2012) Considerable variation, esp. H10 vs R12, error ~ 25 - 50%. Hauser Feshbach not reliable. 44 Ti( a,p) 47 V Sonzogni et al (2000) re-evaluated Hoffman et al (2010) radioactive beam at TRIUMF (DRAGON )

46. Summary: 40 Ca( a,g) 44 Ti and 44 Ti( a,p) 47 Sc are most critical. The former is now better known thanks to Robertson et al but given the dispersion on past measurements further study may be warranted. The latter is still uncertain to about a factor of two or three for the relevant temperature range. The error in rates could compensate for most of the discrepancy between models and the observed signal without invoking unusual explosion geometry – Hoffman et al (2010)

47. INTEGRAL OBSERVATIONS OF 26 Al (t 1/2 = 0.72 My AND 60 Fe (t 1/2 = 1.5 - 2.6 My) IN THE ISM Brightness Ratio = 0.15 +- 0.04 Necessary mass ratio = (0.15)(60/26) = 0.35 26 Al (32 sigma signal) 60 Fe (5 sigma signal)

48. Target 0.35 Timmes, Woosley and Weaver (1995) 0.36 (prediction) Woosley and Heger (2007) new rates and opacities and mass loss 1.8 Woosley and Heger (2007) adjusting only 26 Al cross sections using experiment rather than HF 0.95 further changes in 59,60 Fe and 22 Ne( a,n) could reduce it by as much as 2 0.50?? Meynet, Palacios, Limongi, Chieffi additional effects due to treatment of rotational mixing, convective algorithm, metallicity, mass loss, and IMF.

49. 60 Fe

50. 60 Fe(n, g ) 61 Fe 30 keV 9.9 +- 1.4 +- 2.8 mb measured by activation. Answer sensitive to uncertain t 1/2 ( 60 Fe) Uberseder et al, PRL, 102, 1101 (2009) 59Fe(n, g ) 60 Fe ( t 1/2 = 44.5 d) being studied by photodissociation of 60 Fe at GSI Uberseder PhD thesis (Notre Dame) just completed. Paper in preparation – “ will be submitted in a few weeks” No big surprises The production of 60 Fe is most sensitive to 59 Fe(n, g ) 60 Fe target 7.8 x 10 15 atoms - Schumann et al (NIMPA 2010) - chemical extraction from accelerator waste - 60 Fe

51. 26 Al is produced both by hot hydrogen burning (and is enhanced in massive star winds) and supernova explosions by explosive neon burning. 26 Al (n,p) 26 Mg and 26 Al(n, a ) 23 Na in progress at TRIUMF and LANSCE by Buchmann et al. Target fabrication at TRIUMF. Pulsed neutron measurements at LANL. Will narrow uncertainty but corrections for isomeric state (228 keV) will remain uncertain. Some information from reverse reactions. 26 Al

52. CONCLUSIONS A time of rapid progress in laboratory nuclear astrophysics. Key reaction rates near the valley of beta-stability are finally within grasp to the desired accuracy A major frontier now is radioactive beams and targets Bridging the laboratory and theoretical models with refereed nuclear data archives is an essential and very cost effective activity