1 / 25

Workshop on “ Physics at a Multi Mwatt proton source“

“Challenges in Nuclear Astrophysics with a next generation ISOL facility“. K.-L. Kratz Kernchemie + VISTARS, Universität Mainz. Workshop on “ Physics at a Multi Mwatt proton source“. Historically, nuclear astrophysics has been concerned with. Observational instrumentation:.

astin
Download Presentation

Workshop on “ Physics at a Multi Mwatt proton source“

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. “Challenges in Nuclear Astrophysics with a next generation ISOL facility“ K.-L. Kratz Kernchemie + VISTARS, Universität Mainz Workshop on “Physics at a Multi Mwatt proton source“ CERN 05/2004

  2. Historically, nuclear astrophysics has been concerned with Observational instrumentation: • Interpretation of observed abundance distributions, or specific signatures of luminosity curves; • Description of originating nucleosynthesis processes(see, e.g. B²FH, 1957!) • meteoric and overall solar abundances; • ground- and satellite-based telescopes, like ImagingSpectrograph (STIS) at Hubble or HIRES at Keck I, and g-ray satellites like INTEGRAL or x- ray observatories CHANDRA and XMM- Newton CERN 05/2004 CERN 05/2004

  3. Nuclear Physics in Stellar Binaries Cataclysmic binaries are potential site for explosive nuclear reaction driven processes - thermonuclear runaway - • Nova: thermonuclear runaway burning on accreting white dwarfs • Supernova type I: cataclysmic burning on white dwarfs • X-ray bursts: thermonuclear runaway on accreting neutron stars • X-ray pulsars: steady burning on accreting neutron stars from Wiescher et al. (2003) CERN 05/2004 CERN 05/2004

  4. rp-process at “low” temperatures at “high” temperatures Novae X-ray bursts explosive H-burning on surface of white drawfs explosive H- and He-burning on surface of accreting neutron stars cycle pattern due to Cb-barriers; (p,g)-(g,p) equilibrium , “waiting-point” concept; + p-capture and b+-decay sequence of fast p-captures with similar time scales; and subsequent b+-decay path close to stability path far away from stability up to 19K - 23V up to 46Pd - 50Sn + (p,g); (g,p); (p,a); T1/2(b+) + (p,g); (g,p); (2p,g); T1/2(b+) on odd-Z, T = + ½ nuclei on even Z, T = - ½ nuclei Z Z e.g. 23Mg, 27Si, 31S, 43Ti e.g. 68Se, 72Kr, 76Sr, 80Zr, 84Mo ... nucl. masses reaction Q-values CERN 05/2004

  5. Most relevant Nuclear Structure Experiments CERN 05/2004

  6. Self consistent calculations Consequences for isotopic abundances! 31S, slower depletion  mixed towards surface 39Ca, slower depletion  mixed towards surface CERN05/2004 CERN 05/2004 from M. Wiescher 2003

  7. Xe (54) I (53) Te (52) Sb (51) Sn (50) In (49) Cd (48) Ag (47) Pd (46) 59 Rh (45) Ru (44) 57 58 Tc (43) Mo (42) Nb (41) Zr (40) 56 Y (39) Sr (38) 54 55 Rb (37) 53 Kr (36) 51 52 Br (35) 49 50 Se (34) As (33) 45 46 47 48 Ge (32) Ga (31) 42 43 44 Zn (30) 41 Cu (29) 37 38 39 40 Ni (28) Co (27) 33 34 35 36 Fe (26) Mn (25) 31 32 Cr (24) V (23) 29 30 4 Ti (22) Sc (21) 25 26 27 28 2 Ca (20) 56Ni K (19) 23 24 Ar (18) Cl (17) 21 22 1 S (16) P (15) 17 18 19 20 Si (14) 3 Al (13) 15 16 Mg (12) Na (11) 14 Ne (10) F (9) 11 12 13 O (8) N (7) 9 10 C (6) B (5) 7 8 Be (4) Li (3) He (2) 5 6 H (1) 3 4 0 1 2 Waiting points in the rp-process Endpoint Sb-Te cycle Impact on X-ray burst luminosity curve 73Rb 69Br Upperandlowerlimits of Audi-Wapstra mass extrapolations 65As Issues: Timescale of the rp process (56Ni, 65As, 69Br, 73Rb) from Wiescher et al. (2003) CERN 05/2004

  8. The Energy production in X-ray bursts characterized by 4 periods at increasing temperature (2 x 108 - 2 x 109 K): ignition phase Upperandlowerlimits of Audi-Wapstra mass extrapolations 2 Hot CNO-cycles, triggered by p-captures on C, N, O isotopes; formation of 14N, 14,15O, 17F and 18Ne waiting-point nuclei. ‚ignition of triple-a-process 3 Rapid depletion of 14,15O and 18Ne by -reactions to 24Si; further p- and -captures to waiting-point isotopes 29S, 34Ar; and subsequent -captures to main waiting-point nucleus 56Ni. 4 ƒdormant period 1 Here, further processing is halted by (p,g)-(g,p) equilibrium; energy production drops rapidly; and temperature starts to decrease. „rp-process beyond 56Ni Start at T9 = 1.5 x 109 - 1.0 x 109 K; cooling phase down to ~ 5x 108 K; several even-even waiting-points 64Ge, 68Se, ... 100Sn; overall time scale ~ 500s. Clear abundance peaking of light p-nuclei74Se, 78Kr, 84Sr, 92Mo, 96,98Ru, so far not explained in classical p-process scenarios. CERN 05/2004

  9. -2 10 -3 10 abundance -4 10 -5 10 -6 10 0 20 40 60 80 100 120 mass number The fate of the processed matter? Final abundance distribution • Ejected out of neutron star • grav. potential •  contribution to light • p-nuclei abundances • Embedded into neutron • star crust •  modification of crust • composition from Wiescher et al. (2003) CERN 05/2004

  10. 68Ca 56Ar 34Ne (1.5 x 109 g/cm3) rp-process e- capture pycnonuclear reactions The fate of matter in the neutron star crust density border of known masses 56Ni Neutron Drip Line Ni (28) Fe (26) Electron capture Cr (24) Ti (22) Ca (20) Ar (18) S (16) (2.5 x 1011 g/cm3) Si (14) Mg (12) Electron capture and n-emission Ne Pycnonuclear fusion (1.5 x 1012 g/cm3) from Wiescher et al. (2003) CERN 05/2004 CERN 05/2004

  11. Conclusion • Nuclear structure along rp-process reaction path (N=Z line) determines abundance distribution in the ashes • Endpoint is associated with -unbound nuclei beyond Z,N=50 • Electron capture drives abundance distribution towards the neutron drip line (timescale >105 y) • Electron capture induced neutron emission drives abundance distribution towards Z<12 • Pycno-nuclear reactions from Wiescher et al. (2003) CERN 05/2004

  12. Nuclear Physics in Neutron-RichExplosive Environments High neutron to seed ratio (10 - 150) for rapid neutron-capture processes only in explosive astrophysical sites • Supernova type II: explosive shell burning (He, C) high-entropy neutrino wind ejecta • Neutron-star (NS) mergers: low-entropy ejecta of NS matter • Axial jets in SNe: blast ejecta from rotating NS accretion disk CERN 05/2004 CERN 05/2004

  13. r-process Supernova II moderate n-densities (nn  1023) explosive (He, C, Si) shell burning high-entropy bubble , core scenario Neutron Star Mergers high n-densities (nn  1030) very n-rich ejecta fission “recycling“ nuclear data needs direct: Qb, Sn, T1/2, Pn, sng of „“waiting-point nuclei“ at Nmag indirect: development of nuclear structure with isospin CERN 05/2004 CERN 05/2004

  14. N/Z ) 0 w g h 9/2 g 126 of 9/2 p 1/2 i 7.0 f 13/2 112 5/2 p Units h ;f 3/2 i 9/2 5/2 13/2 p h 1/2 ( 6.5 9/2 f p 7/2 3/2 f 7/2 82 Energies h 11/2 70 6.0 h 11/2 g d 7/2 3/2 g d 7/2 s 3/2 1/2 5.5 s d 1/2 5/2 d 50 5/2 Single – Neutron g g 9/2 5.0 9/2 40 p 1/2 f 5/2 f p 5/2 1/2 70% 10% 100% 40% Strength of l -Term 2 132Sn B. Pfeiffer et al., Acta Phys. Polon. B27 (1996) 50 82 New Nuclear structure at drip-lines, as „shell quenching“? • Defiencies prior to the main peaks were attributed by our group to nuclear structure effects: • too strong shell strength for extremely neutron-rich magic nuclei far from stability • nuclear models adjusted to stable nuclides • new physics far from stability? FK²L (Ap.J. 403 ; 1993) “..the calculated r-abundance ‘hole‘ in the A  120 region reflects ... the weakening of the shell strength ... below “ CERN 05/2004

  15. R-abundance peaks and neutron-shell numbers ...still today important r-process properties to be studied experimentally and theoretically. already B²FH (Revs. Mod. Phys. 29; 1957) C.D. Coryell (J. Chem. Educ. 38; 1961) “climb up the staircase“ at N=82; major waiting point nuclei; “break-through pair“131In, 133In; K.-L. Kratz (Revs. Mod. Astr. 1; 1988) climb up the N= 82 ladder ... A  130 “bottle neck“ total r-process duration r “association with the rising side of major peaks in the abundance curve“ CERN 05/2004

  16. Qb-value of 130Cd82 Way-Wood diagram  Z=50 and N=82 shell closures „visible“ Qb Mass model predictions Hilf et al. (GTNM, 1976) 7.57 MeV Möller et al. (FRDM, 1995): 7.43 MeV Aboussir et al. (ETFSI, 1995): 7.87 MeV Duflo & Zuker (1995) 7.56 MeV Dobaczewski et al. (HFB/SkP, 1996): 8.93 MeV Pearson et al. (ETFSI-Q, 1996): 8.30 MeV Audi & Wapstra (Mass Eval., 1997): 8.50 MeV Goriely et al. (HFBCS, 2001) 7.00 MeV Samyn et al. (HFB-2, 2002) 7.64 MeV Brown et al. (localOXBASH, 2003): 8.75 MeV High Qb-value is a clear signature for an N=82 „shell quenching“ below 132Sn50 CERN 05/2004

  17. FRDM ETFSI-1 HFB-2 ETFSI-Q CERN 05/2004

  18. 0+ 0+ 110Zr 110Zr … Q  9.27 MeV Q  9.27 MeV 1+ 7.64 1+ 7.04 0.6% 6.44 1+ GT GT 1+ 5.22 Sn  3.73 MeV 1+ Levels [g9/2g7/2] Sn  3.21 MeV 73% 10% 1.13 1+ 2- 0 B. Pfeiffer et al., Acta Phys. Polon. B27 (1996) 3- 0 110Nb Zr 110 40 70 ... a new double-magic „waiting-point“ nucleus? Beta-decay Normal shell strength strongly deformed (2=0.31) Shell strength quenched spherical T½ = 14 ms Pn = 0.7 % T½ = 88 ms Pn = 8 % 1.67 0.85 110Nb K.-L. Kratz, A. Ostrowski (2004) CERN 05/2004

  19. 0+ 0+ Sn 110Zr 110Zr DC 7/2- 1240 4893 f5/2 4070 p1/2 3/2- 565 s1/2 3987 477 RC 1/2- 2507 9/2- p9/2 73 Sn 3/2+ 0 d3/2 2064 DC 1/2- 111Zr71 111Zr71 1246 40 40 f7/2 g7/2 960 0 h11/2 Zr 110 40 70 ... a new double-magic „waiting-point“ nucleus? Normal shell strength strongly deformed (2=0.34) Shell strength quenched spherical Neutron-capture via (d,p) in inverse kinematics Sn(111Zr)  2.30 MeV 3/2- 565 keV 1/2- 477 keV 7/2- 1246keV 1/2- g.s. B. Pfeiffer et al., Acta Phys. Polon. B27 (1996) K.-L. Kratz, A. Ostrowski (2004) CERN 05/2004

  20. Ultra-metal-poor Halo stars Th-U cosmochronometer • Th-U chronometer ideal for dating of solar system. • Lower limit for age of the Universe requires models • of Galactic chemical evolution. • High-resolution optical spectroscopy of ultra-metal- • poor, very old Halo red giant stars opens • new perspectives: • One (or few) nucleosynthesis events seeded ISM. • Scaled solar system r-process abundances for • 56  Z  79. • Radioactive dating requires „production ratios“. • Th/U ratio (hopefully) less affected by extra- • polations of nuclear structure Abundances in BD+17o3248 Calculated abundances of the long-lived actinides test for short-lived isotopes expected in Galactic cosmic rays. CERN 05/2004

  21. CERN 05/2004

  22.    CERN 05/2004

  23. Isotope ratios in metal-poor, r-process-rich stars Time For a limited number of elements (as Rb, Ba, Eu), not only elemental but also isotopic abundances have been observed in stars. This provides crucial information on the timing of the neutron-capture processes, the s- and r-process, in the early Galaxy. Science 299 (2003) 70 CERN 05/2004

  24. Future developments • Experimental data for extremely neutron-rich nuclei needed. • Radioactive Ion Beam facilities • - extension of the N=50 and 82 regions as close to drip-line as possible • - N=126 “waiting-point” nuclei • Ongoing sky surveys detect more metal-poor stars. • More high-resolution optical spectroscopy in stars of varying • metallicity is needed. • More precise dating of the on-set of s-process nucleosynthesis. • Scenarios/sites for the r-process • - Effectively constrain “classical” parameter studies • - Impact of the network calculations? • Are there different r-processes? CERN 05/2004

  25. N/Z Future Facility Reach(here: RIA yields) g 9/2 g 126 9/2 p 1/2 i 7.0 f 13/2 112 5/2 p h ;f 3/2 i 9/2 5/2 13/2 p h 1/2 6.5 9/2 f p 7/2 3/2 f 7/2 82 Single – Neutron Energies (Units of ħ0) h 11/2 70 6.0 h 11/2 g d 7/2 3/2 g d 7/2 s 3/2 1/2 5.5 s d 1/2 5/2 d 50 5/2 g 9/2 g 5.0 9/2 40 p 1/2 f 5/2 f p 5/2 1/2 70% 10% 100% 40% Strength of l² -Term Reach of radioactive beam facilities Future facility reach Fe Present facility reach Known half-life Reach for at least a half-life measurement From K.-L. Kratz (KCh MZ) and H. Schatz (MSU) new magic numbers ? CERN 05/2004

More Related