1. Critical Nuclear Physics Needs for Astrophysical Nucleosynthesis Studies James W. Truran Physics Division Argonne National Laboratory and Department of Astronomy and Astrophysics University of Chicago March 23 rd, 2010

2. Cosmic Nucleosynthesis Perspective  The Universe emerged from the Big Bang with a composition consisting of hydrogen, helium, 2 D, 3 He, and 7 Li. The first stars and galaxies were born with this “primordial” composition.  The heavy elements with which we are familiar - from carbon and oxygen, to iron,.. to uranium - are the products of nuclear processes associated with the evolution of stars and supernovae of Types Ia and II.  The classic papers by Burbidge, Burbidge, Fowler, and Hoyle (1957) and Cameron (1957) provided the perspective from which we now view this nucleosynthesis history.  The respective efforts by Cameron and Fowler to improve the nuclear physics input for nucleosynthesis studies largely reflect today’s needs for both theory and experiment:  Fowler and his collaborators focused during the 1950s and 1960s on nuclear experiments involving light element reactions relevant to early stages of stellar energy generation - efforts which have established the empirical foundations of stellar evolution theory.  Strongly motivated by Paul Merrill’s identification of the presence of technetium in red giant stars, Cameron focused rather on the mechanisms of heavy element synthesis and the need for theoretical estimates of reaction rates and other nuclear properties. CRL-41

3. “Cosmic” Abundances of the Elements Signatures of nuclear systematics:  -particle nuclei are dominant 12 C --- 40 Ca dominance of unstable  -nuclei decay products: 44 Ti  44 Ca, 48 Cr  48 Ti 52 Fe  52 Cr, 56 Ni  56 Fe 60 Zn  60 Ni, 64 Ge  64 Zn 68 Se  68 Zn, 72 Kr  72 Ge nuclear statistical equilibrium centered on mass A=56 ( 56 Ni in situ) neutron shell structure reflected in the heavy element region at magic numbers N=50, 82, and 126 (s- and r-processes) Massive Stars & SNe r-process s-process

4. Outline  Helium Burning Reactions  CNO hydrogen burning in novae and X-ray bursts  Explosive Nucleosynthesis in supernovae: SNe Ia and SNe II  Some interesting long lived radioactivities  Heavy element (A>60) nucleosynthesis mechanisms  s-process  r-process  p-process  Clues from abundance studies

5. 12 C synthesis realized in red giant (AGB) stars in ‘incomplete’ helium burning regions (helium burning shells). Stellar helium burning proceeds mainly by the two reactions: 3   12 C and 12 C( ,  ) 16 O.

6.  + 16 O --> 12 C +  beam target bubbles Superheated water will nucleate from  and 12 C recoils The detector is insensitive to  -rays from the beam. The target density is 1000x higher than that of previous experiments. Superheated water will nucleate from  and 12 C recoils The detector is insensitive to  -rays from the beam. The target density is 1000x higher than that of previous experiments.  -ray beam provided by the HI  S facility at Duke University. Water has been depleted in heavy isotopes of oxygen and deuterium. Backgrounds such as  -emitters can be rejected effectively. First experiment has been scheduled for April 2010  -ray beam provided by the HI  S facility at Duke University. Water has been depleted in heavy isotopes of oxygen and deuterium. Backgrounds such as  -emitters can be rejected effectively. First experiment has been scheduled for April 2010

7. Outline  Helium burning reactions  CNO Hydrogen Burning and “breakout:” Novae and X-ray Bursts  Explosive Nucleosynthesis in supernovae: SNe Ia and SNe II  Some interesting long lived radioactivities  Heavy element (A>60) nucleosynthesis mechanisms  s-process  r-process  p-process  Clues from abundance studies

8. Novae & X-Ray Bursts: Standard Models  Classical Novae and X-Ray Bursters involve thermonuclear explosions in accreted hydrogen-rich envelopes of white dwarfs and neutron stars, respectively, in close binary systems.  Accretion of matter from their companion leads to growth of the envelope until a critical pressure is achieved at its base to trigger a thermonuclear runaway.  The violence of the ensuing outbursts depends strongly on the degree of degeneracy at the base of the envelope and the composition of the available nuclear fuel. The early stages of the outbursts of both novae and X-ray bursts witness rapid energy release on a dynamic time scale, moderated in a critical way by the operation of the hot (  + -limited) CNO cycles. Nova V1974 Cygni 1992 X-ray Burst GS 1826-24

9. Hot CNO Cycles and Breakout Reactions 14 O(  p) 17 F(p,  ) 18 Ne(β + ν) 18 F(p,α) 15 O Break-Out Reactions (T > 80 million K) CNO Cycles)  + -Decay Constrained Implications for: novae and X-ray bursts 15 O(    e(p,γ) 20 Na

10. 10 Nucleosynthesis Processes p-process Supernovae? Supernovae

11. Courtesy: H. Schatz

12. Classical Nova Explosions under Extreme Conditions  Townsley and Bildsten (2004) have shown that their exists a subclass of nova events occurring on massive white dwarfs accreting at extremely low rates and characterized by high densities and low central temperatures (T ≈ 5 million Kelvin).  Glasner and Truran (2009; 2010) have shown that such conditions lead to violent nova events with peak temperatures exceeding 400 million Kelvin, such that “breakout” from the conventional CNO cycles can occur. This may explain the anomalous abundance patterns seen in the ejecta of such systems.  Glasner and Truran have also demonstrated the sensitivities of breakout to critical reaction rates in the hot CNO sequences. We find a particularly strong dependence on the rate of the 15 O(α,γ) 19 Ne and a weaker sensitivity to the rate of the 14 O(α,γ) 17 F reaction. Also we note a constraint on flow past the iron peak at 64 Ge.

13. ( Glasner and Truran 2009 ) “Breakout,” the 15 O(α,γ) 19 Ne Rate, and Nova Abundances (The accreted matter was assumed to include no elements past oxygen.) ( Glasner and Truran 2010 ) Note that heavier elements synthesized in nova events are observable in nebular remnants > a direct observational test.

14. Indirect (  ) measurements  )= for 15 O(  ) 19 Ne: E r J Need:    from T       Tan et al. (2005), Kanungo et al. (2006) and Mythili et al. (2008) have measured  γ.  We then also need a determination of   or      Davids et al. (2003), Rehm et al. (2003) and Tan et al. (2007) in observing the breakdown to 15 O+α find     < 4x10 -4. A more accurate determination is clearly necessary.

15. Outline  Helium burning reactions  CNO hydrogen burning in novae and X-ray bursts  Explosive Nucleosynthesis in SNe Ia and SNe II  Heavy element (A>60) nucleosynthesis mechanisms  s-process  r-process  p-process  Clues from abundance studies

16. Synthesis of Intermediate Mass and Iron-Peak Nuclei  Following helium burning, the elements from neon to zinc are formed in late stages of energy generation (carbon, neon, oxygen, and silicon burning) in massive stars (M ≥ 10 M  ) and in supernovae Type Ia and Type II.  The critical first step here involves the fusion reactions 12 C( 12 C,p) 23 Na and 12 C( 12 C,α) 20 Ne.  Currently utilized reaction rates are obtained by extrapolation from higher energy ranges that do not involve resonances. Recent experimental investigations of the 12 C+ 12 C rate (e.g. Zickefoose et al. 2010) are focusing on extending the studied region down to the vicinity of the Gamow window. (See also Spillane et al. 2007).  Challenges remain to confirm the production levels of intermediate mass and iron nuclei formed under explosive burning conditions in Type Ia and Type II supernova events.

17. COSMIC ABUNDANCES The abundance history of the “intermediate mass” nuclei Si-Ca relative to “iron-peak” nuclei ( 56 Fe/ 56 Ni) provides important constraints on SNe Ia and SNe II models.

18. “Explosive Iron-Peak Nucleosynthesis”  Explosive nucleosynthesis is a complicated process. The nuclear products are sensitively dependent upon:  thermonuclear reaction rates (level densities are critical),  weak interaction rates (which serve to convert protons to neutrons - neutronization - and thereby reduce Y e and decrease the abundances of proton rich nuclei), and  the (short) dynamic timescales appropriate to supernovae.  Cameron (1963) recognized that the products of heavy element synthesis under explosive conditions were sensitive to the relative rates of strong and weak interactions and to the timescale on which synthesis occurred. This has ultimately led to the appreciation of the fact that the production of iron-peak nuclei in supernovae occurs under neutron-poor conditions (e.g. Y e ~ 0.5) such that the dominant products are proton-rich nuclei (e.g. 56 Ni).  Critical input nuclear physics includes experimental and theoretical rates and/or lifetimes for nuclei near the alpha-line, for both nuclear reactions and weak interactions.

19. Why 56 Ni ?  Pre-explosion compositions involve largely nuclei of Z  N, viz. 12 C, 16 O, 28 Si (for SNe II).  Explosive burning at temperatures T > 4x10 9 K typically occurs on timescales  seconds.  Supernova nucleosynthesis sees reactions occurring on a dynamical timescale. (Experimental rate determinations and Hauser-Feshbach calculations are critical input.)  Weak interactions proceed too slowly to convert any significant fraction of protons to neutrons. (Weak interaction rates are critical input.)  It follows that the main (in situ) iron-peak products of explosive nucleosynthesis in supernovae are proton-rich nuclei of Z  N, viz. 44 Ti, 48 Cr, 52 Fe, 56 Ni, 60 Zn, and 64 Ge (Cameron 1963; Truran, Arnett, and Cameron 1967). 56 Ni Production in Explosive Nucleosynthesis

20. Explosive Nucleosynthesis of Fe-Peak Nuclei 44 Ti 47 V 48 Cr 52 Fe 51 Mn 55 Co 43 Sc 40 Ca 60 Zn 65 Ge 64 Ge 68 Se 42 Ca 50 Cr 46 Ti 58 Fe 52 Cr 56 Fe 54 Fe 53 Cr 47 Ti 49 Cr 57 Fe 48 Ti 49 Ti 50 Ti 54 Cr 64 Zn 63 Ga 61 Zn 62 Zn 58 Ni 60 Ni 67 Zn 66 Zn 62 Ni 61 Ni 57 Ni 53 Fe 46 Ca 44 Ca 43 Ca 64 Ni 51 V 50 V 45 Sc 48 Ca 59 Co 55 Mn 70 Ge 72 Ge 65 Cu 63 Cu 59 Cu 68 Zn 72 Kr 45 Ti 67 As 66 Ge 69 Ga 71 Ga 70 Zn Z  N  56 Ni Iron peak nucleosynthesis occurs at Y e ≈0.5 in both SNe Ia and SNe II 74 Ge

21. Supernova Nucleosynthesis Contributions  Type Ia Supernovae : Thermonuclear explosions of CO white dwarfs.  Type II Supernovae: Core collapse driven events in massive stars.  In both instances,the formation of iron peak elements in explosive nucleosynthesis occurs under neutron-poor conditions. This is reflected in the 56 Ni  56 Co  56 Fe signatures in both Type Ia and Type II supernova light curves … and in the isotopic compositions of iron-peak elements in Solar matter. (Iwamoto et al. 1999)(Thielemann et al. 1992) SNe 1987ASNe Ia

22. 56 Ni Production in SNe Ia / Nomoto 56 Ni (Y e ≅ 0) Neutron Rich Matter Intermediate Mass Elements: Si - Ca (Timmes, Brown, and Truran 2003)

23. Interesting Long Lived Radioactivities  Long lived radioactivities that are products of explosive nucleosynthesis (e.g. 7 Be, 22 Na, 26 Al, 44 Ti, 56 Ni, 57 Ni, 60 Fe,.. 232 Th, 235 U, 238 U..) can test and constrain models. Both 7 Be (53.28 d) and 22 Na (2.604 a) are anticipated products of classical nova explosions. Their abundance levels are sensitive functions of the convective/temperature history. The three long lived actinide isotopes 232 Th, 235 U, 238 U constitute important chronometers of the earliest stages of star formation activity in our Galaxy.  Supernovae represent the source of the interesting radioactivities 44 Ti, 56 Ni, and 57 Ni in nucleosynthesis. Detections of gamma rays from 56 Ni and 57 Ni have informed us both of the mass of 56 Fe in Type II supernova ejecta and of the 56 Fe/ 57 Fe ratio emerging from these events. We also understand the role of 56 Ni in powering the light curves of Type Ia supernovae, utilized as distance indicators.  44 Ti decay gamma rays have been detected from the Cas A Type II supernova remnant (see figure). The measured flux implies that if 44 Ti and 56 Ni were formed in a ratio consistent with the solar 44 Ca/ 56 Fe ratio, the Cas A supernova should have been brighter. Alternatively, the 44 Ti may simply have been overabundant relative to mass 56 in that Type II event (the Ti/Ca ratio seen in halo stars is ≈ 3 times solar). Experimental determinations of the rates of production and destruction of 44 Ti remain critical input.

24. Outline  Helium burning reactions  CNO hydrogen burning in novae and X-ray bursts  Explosive Nucleosynthesis in supernovae: SNe Ia and SNe II  Some interesting long lived radioactivities  Heavy Element (A>60) Nucleosynthesis Mechanisms  s-process  r-process  p-process  Clues from abundance studies

25. Neutron-Capture Processes of Heavy Element Synthesis  Our picture of the processes of heavy element synthesis has become considerably more complicated with time. Early work identified the s- and r-processes, with a relatively small contribution from the p- process.  We now understand that there are two distinguishable contributions (a “weak” and a “main” component) to both of the neutron capture processes: the s-process and the r-process.  The challenges to theorists include the need to identify the astrophysical sites in which this nucleosynthesis occurs and to explain the distinctive features of the diverse components. (Cameron 1963)

27. Neutron Capture Cross Sections:  theory /  experiment Truran and Cameron (1965) Macklin and Gibbons (1957) Rauscher, Thielemann and Kratz (1996) Thielemann, Arnould and Truran (1987) Bao and Kappeler (1986) Note systematic trends through positions of shell closures arising from level density variations. Neutron capture cross section uncertainties (Käppeler et al. 2007)

28. Identifying the r-Process Component in Solar System Matter Neutron Capture Cross Sections

29. CS 22892-052 Search for a Second r-Process  The robust r-process abundance pattern in the regime from barium through the actinides does not extend below mass A ≈ 130, although the classic r-process model extends down to mass A ≈ 70. A second component is thus essential. Two possibilities are:  the νp-process (Fröhlich 2007)  an r-process associated with the mass shells ejected in Type II events “weak” r-process

30. 30 Nucleosynthesis Beyond Fe-group: νp-process With neutrinos oWithout neutrinos  Proton-rich matter is ejected under the influence of neutrino interactions.  Nuclei form at distances where a substantial antineutrino flux is present.  True rp-process is limited by slow  decays, e.g.  ( 64 Ge).  Antineutrinos help bridging long waiting points via (n,p) reactions: (Frebel et al. 2005)

31. 31 Numerical Effects of Rate Variations (p,γ) rates Fröhlich, Tang, and Truran (2010) (n,p) rates

32. 32 503536373839404142434445464748495152 53 52 Te 106 Te 107 Te 108 Te 109 Te 110 Te 111 Te 112 51 Sb 103 Sb 104 Sb 105 Sb 106 Sb 107 Sb 108 Sb 109 Sb 110 Sb 111 50 Sn 100 Sn 101 Sn 102 Sn 103 Sn 104 Sn 105 Sn 106 Sn 107 Sn 108 Sn 109 Sn 110 49 In 98 In 99 In 100 In 101 In 102 In 103 In 104 In 105 In 106 In 107 In 108 In 109 48 Cd 97 Cd 98 Cd 99 Cd 100 Cd 101 Cd 102 Cd 103 Cd 104 Cd 105 Cd 106 Cd 107 Cd 108 47 Ag 94 Ag 95 Ag 96 Ag 97 Ag 98 Ag 99 Ag 100 Ag 101 Ag 102 Ag 103 Ag 104 Ag 105 Ag 106 Ag 107 46 Pd 91 Pd 92 Pd 93 Pd 94 Pd 95 Pd 96 Pd 97 Pd 98 Pd 99 Pd 100 Pd 101 Pd 102 Pd 103 Pd 104 Pd 105 Pd 106 45 Rh 89 Rh 90 Rh 91 Rh 92 Rh 93 Rh 94 Rh 95 Rh 96 Rh 97 Rh 98 Rh 99 Rh 100 Rh 101 Rh 102 Rh 103 Rh 104 Rh 105 44 Ru 87 Ru 88 Ru 89 Ru 90 Ru 91 Ru 92 Ru 93 Ru 94 Ru 95 Ru 96 Ru 97 Ru 98 Ru 99 Ru 100 Ru 101 Ru 102 Ru 103 Ru 104 43 Tc 86 Tc 87 Tc 88 Tc 89 Tc 90 Tc 91 Tc 92 Tc 93 Tc 94 Tc 95 Tc 96 Tc 97 Tc 98 Tc 99 Tc 100 Tc 101 Tc 102 Tc 103 42 Mo 84 Mo 85 Mo 86 Mo 87 Mo 88 Mo 89 Mo 90 Mo 91 Mo 92 Mo 93 Mo 94 Mo 95 Mo 96 Mo 97 Mo 98 Mo 99 Mo 100 41 Nb 82 Nb 83 Nb 84 Nb 85 Nb 86 Nb 87 Nb 88 Nb 89 Nb 90 Nb 91 Nb 92 Nb 93 Nb 94 Nb 95 Nb 96 Nb 97 Nb 98 Nb 99 40 Zr 80 Zr 81 Zr 82 Zr 83 Zr 84 Zr 85 Zr 86 Zr 87 Zr 88 Zr 89 Zr 90 Zr 91 Zr 92 Zr 93 Zr 94 Zr 95 Zr 96 Zr 97 39 Y 78 Y 79 Y 80 Y 81 Y 82 Y 83 Y 84 Y 85 Y 86 Y 87 Y 88 Y 89 Y 90 Y 91 Y 92 Y 93 Y 94 Y 95 38 Sr 73 Sr 74 Sr 75 Sr 76 Sr 77 Sr 78 Sr 79 Sr 80 Sr 81 Sr 82 Sr 83 Sr 84 Sr 85 Sr 86 Sr 87 Sr 88 Sr 89 Sr 90 Sr 91 Sr 92 37 Rb 74 Rb 75 Rb 76 Rb 77 Rb 78 Rb 79 Rb 80 Rb 81 Rb 82 Rb 83 Rb 84 Rb 85 Rb 86 Rb 87 Rb 88 Rb 89 Te 105 Ag 93 Tc 85 Mo 83 Nb 81 Zr 78 Zr 79 Y 76 Y 77 Rb 72 Rb 73 N = Z 54 5556 5960 58 67 Z = 50 N = 50 I 109 I 110 I 111 I 112 I 113 I 108 Xe 110 Xe 111 Xe 112 Xe 113 Xe 114 p – process SHIPTRAP REFERENCE NUCLIDES JYFLTRAP (adapted from C. Weber) Penning Trap Mass Measurements (υp=process regime) CANADIAN Penning TRAP at ANL

33. Main r-Process Nucleosynthesis Contributions  Significant efforts have been made to understand the extremely robust r-process abundance pattern observed in the mass range from barium to uranium that characterizes both Solar matter and the oldest (and r-process rich) stars in our Galaxy’s halo.  This robustness strongly suggests – perhaps even demands – that significant fission recycling enables an approach to a stable pattern. This emphasizes the need for a more reliable treatment of fission including an understanding of the fragment distribution.  Critical nuclear input also includes masses (S N ) for nuclei along the capture path, a more refined treatment of nuclear level densities, greater predictability of the behavior near shell closures, and a more extensive study of the beta-decay systematics of deformed nuclei (Möller, Nix, and Kratz 1997).

34. New CPT / Previous CPT measurements CPT Fission Fragment Measurements Ongoing program of measurements since March 2008, target 15 keV uncertainty 38 species, 31 have never been measured by method other than β-endpoint Typically improved precision by factor of 5-10 Adds to 30 measurements taken at CPT in past years with small gas catcher and source

35. R-Process Models “Site-ing” r-Process Nucleosynthesis Helium Shells of SNe II Neutron Star- Neutron Star Collisions Low Mass ( Prompt Expl.) SNe II - Driven Winds SNe II Identification of the r-process sites remains a major challenge.

36. Synthesizing the r-Process Mass Region A = 110-238 Farouqi et al. (2010) r-process calculations in the context of the ‘high entropy wind’ model for two choices of mass model. The possibility of achievement of such high entropy conditions in Type II supernova environments remains a challenging issue (Panov and Janka 2009).

37. Calculated Fit to Solar r-Process Pattern Kratz et al. (2004)

38. Synthesizing the r-Process Mass Region A = 110-238  The two most obvious constraints imposed on the r-process mechanism(s) by spectroscopic studies are: First – that there exist at least two distinct astrophysical sites. Second – that the process responsible for the synthesis of elements past Z = 56 is quite exttraordinarily robust. This points to fission recycling. Panov et al. (2004) provide beta-delayed and neutron-induced fission rates and argue that fission leads to the termination of the r-process. Petermann et al. (2009) have performed representative r-process calculations for different neutron-to-seed ratios that provide a measure of the importance of fission recycling to the robustness of this process. Panov et al. (2004)Petermann et al. (2009)

39. Fission Product Yields from Californium 252 Cf Source at ANL 78 Ni (110 +100 -60 ms) 130 Cd (162 ±30 ms) ( Hosmer et al. 2005) (Hannawald et al. 2001)

40. Concluding Remarks-I  The nuclear physics input requirements for nucleosynthesis studies continue to reflect the importance of both experimental studies of identified “critical” reaction links and theoretical studies built upon statistical properties of nuclei.  In the light mass regime, the 12 C(α,γ) 16 O reaction is of particular importance. The triple-alpha reaction and the 12 C + 12 C reaction also warrant further experimental scrutiny.  Studies of “breakout” from the hot CNO cycles, relevant to both X-ray bursts and novae, will be greatly helped by an improved experimental determination of the rate of the critical 15 O(α,γ) 19 Ne reaction.  Calculations of nucleosynthesis of Ne to Zn nuclei in massive stars and both SNe II and SNe Ia are sensitive both to nuclear reaction rates and to weak interaction rates. Both experimental and theoretical efforts are required. Observations of halo stars provide clues to and constraints upon the ratio of intermediate mass nuclei (Si-Ca) to iron peak nuclei while the range in peak brightness of SNe Ia also reflects variations in the 56 Ni/(Si-Ca) abundance ratio.

41. Concluding Remarks-II  In the regime past the iron peak, a number of processes can contribute. We now know that both the s-process and the r-process patterns demand contributions from at least two different sites.  A critical factor historically has been the separation of the s- and r-components using theory together with experimental neutron capture cross determinations. This may be more complicated in the mass regime A ≅ 60-90 where two s-process contributions may overlap. The dependence of the ‘weak’ s-process on neutron capture cross sections has recently been examined by Pignatari et al. (2010).  The sites of the two (?) r-process contributions remain to be identified as do the range of physical conditions that they may reflect. Required experimental studies include both mass determinations on the proton-rich side relevant to the operation of the νp-process in the mass range A ≅ 60-100 and those on the neutron-rich side relevant to determination of the beta- decay timescales at the waiting points along the r-process path in the vicinity of e.g. 130 Cd, critical to the fission recycling that yields a robust r-process pattern in the extended mass range A ≅ 130-238 such as is observed in “r-process rich” and iron-poor halo stars. Further theoretical studies of beta-delayed and neutron-induced fission are also of interest.

43. Outline  Helium burning reactions  CNO hydrogen burning in novae and X-ray bursts  Explosive Nucleosynthesis in supernovae: SNe Ia and SNe II  Interesting long lived radioactivities  Heavy element (A>60) nucleosynthesis mechanisms  s-process  r-process  p-process  Clues from abundance studies

44. r-Process Neutron Capture Path

45. Heavy Element Abundances in Halo Stars Montes et al. (2007) here have identified two components of enrichment of “r-process” heavy elements in the early stages of Galactic evolution.

46. The r-Process Elements as Displayed in the Oldest Stars (Truran et al. 2002) These behaviors are compatible with nucleosynthesis occurring in SNe II. r-Process Abundances: CS 22892-06 (Sneden et al. 2002) Here 5 r-process-rich stars robustly reproduce the Solar System r-process pattern in the high mass region but exhibit variations below ~ barium. Such stars reveal properties of single r-process events and Galactic r-process enrichment history (Truran et al. 2002).

47. Neutron Capture Cross Sections:  theory /  experiment Truran and Cameron (1965) Macklin and Gibbons (1957) Rauscher, Thielemann and Kratz (1996) Thielemann, Arnould and Truran (1987) Bao and Kappeler (1986) Note systematic trends through positions of shell closures arising from level density variations.

48. (Jordan et al. 2007) 56 Ni, SNe Ia, and the Accelerating Universe

49. Simulations of r process Thanks to JINA for movie

50. Nickel Production in SNe Ia

51. Nuclear Physics Impact on XRB Light Curves Courtesy: H. Schatz

52. Solar System Iron Production  The abundances of most of the iron-peak nuclei in Solar System matter were formed under proton rich (Y e ≈ 0.5) conditions in explosive nucleosynthesis.  This is reflected in isotopic production of even-Z elements. o 48 Ti and 49 Ti formed in situ as 48 Cr and 49 Cr o 50 Cr as 50 Cr: 52 Cr and 53 Cr formed as 52 Fe and 53 Fe o 54 Fe as 54 Fe; 56 Fe and 57 Fe formed as 56 Ni and 57 Ni o 58 Ni as 58 Ni; 60 Ni, 61 Ni, 62 Ni formed as 60 Zn, 61 Zn, and 62 Zn o 64 Zn contributions from 64 Ge ? o 72 Ge contributions from 72 Kr ? o Odd-Z: 51 V ( 51 Mn), 55 Mn ( 55 Co), 59 Co ( 59 Cu), 63 Cu ( 63 Ga)  The isotopic compositions of Cr, Fe, and Ni are derived from isotopes of different elements formed in explosive nucleosynthesis.

53. 53 Sensitivity of the p-process p-process nucleosynthesis depends on:  Nuclear masses  Spin and level information also important  Recent efforts with Canadian Penning Trap, JYFLTRAP, SHIPTRAP  Reaction rates  (p,  ), (n,p), (n,  ),   -decays  Neutrino induced reactions  Antineutrino charged current reactions  Neutral current neutrino reactions  The figure reflects the nucleosynthesis patterns in stars of the lowest known metallicities with overabundances of elements through strontium. Fröhlich, Tang, Truran (in prep ) (Frebel et al. 2005)

54. Main r-Process Nucleosynthesis Contributions  Significant efforts have been made to understand the extremely robust r-process abundance pattern observed in the mass range from barium to uranium that characterizes both Solar matter and the oldest (and r-process rich) stars in our Galaxy’s halo.  This robustness strongly suggests – perhaps even demands – that significant fission recycling enables an approach to a stable pattern. This emphasizes the need for a more reliable treatment of fission including an understanding of the fragment distribution.  Critical nuclear input also includes masses (S N ) for nuclei along the capture path, a more refined treatment of nuclear level densities, greater predictability of the behavior near shell closures, and a more extensive study of the beta-decay systematics of deformed nuclei (Möller, Nix, and Kratz 1997).

55. Mass Measurement Requirements For r-process calculations, need mass uncertainty ~ 15 keV/c 2 (1 : 10 7 ) Relevant nuclei are short-lived, do measurement in < 1 second Do survey over many nuclides ( > 100) 252 Cf spontaneous fission yields 78 Ni (110 +100 -60 ms)

56. 2-neutron separation energy: CPT results vs. FRDM Approximate r- process path

57. 2-neutron separation energy: CPT results vs. AME03 Approximate r- process path