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News on C 12 from  -decay and reaction studies

News on C 12 from  -decay and reaction studies. Why study 12 C ? New results from -decay studies Conclusions. Hans O. U. Fynbo Department of Physics and Astronomy University of Aarhus, Denmark. York, April 19, 2006. Historic Introduction. Hoyle.

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News on C 12 from  -decay and reaction studies

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  1. News on C12 from -decay and reaction studies • Why study 12C ? • New results from -decay studies • Conclusions Hans O. U. Fynbo Department of Physics and Astronomy University of Aarhus, Denmark York, April 19, 2006

  2. Historic Introduction Hoyle Hoyle predicts 7.6MeV state from abundances of He, C and O and finds it experimentally 1956 Morinaga interprets 7.6MeV state and predicts 2+ state near 9MeV 1957 Fowler determines J of 7.6MeV state and finds a very broad state near 10MeV 1966 Morinaga interprets 10MeV state as his 2+ state Fowler Morinaga 10 0+/2+ 7.6 0+ 3 4.4 2+ 0 0+ 12C E in MeV

  3. B2FH 1956 Fowler Burbridge Hoyle Burbridge Suggested most elements above helium were formed in stars and not in B.B.

  4. Morinaga’s Idea for rotational bands in n nuclei 10.3 S.Courtin’s talk Charissa collab. • Ongoing theoretical interest : • Ab-initioPieper, NP A751 (2005) 516. • AMDKanada En’yo, PRL 81 (1998) 5291 • FMDFeldmeier • SMNavratil, Vary & Barrett, PRL 84 (2000) 5728 • U(+1) groupBijker & Iachello, PRC61 (2000) 67305 • Clustertoo many to do justice 2+ ? 2+ ? Bold conjecture shortly after work of Aa.Bohr on rotational motion

  5. The rate(s) of the 3 process Nacre assumes 2+ state at 9MeV Caughlan & Fowler do not

  6. Current situation 7.377 0+ 7.275 a+a+a 15.3 (2+) 15.11 1+ 14.08 4+ 13.35 (2-, 4-) 12.71 1+ 11.83 2- 10.27 11.2 (2+) 10.84 1- (0/2+) 10.3 2+ 9.641 3- 7.65 0+ a+a+a 7.275 8Be+a 4.4389 2+ 0 0+ Levels according to TUNL

  7. Why it isn’t all known

  8. E=9.9(3) MeV 2+ E=10.0(3) MeV 0+ RCNP (2004) ”Standard” approach :12C+a 12C*+a’ 13C 16O 16O? E=11.46 MeV 2+ E=9.8(4) MeV 0+ Texas A&M (2003)

  9. -decay measured: • 1950 by Alvarez12N • 1957 by Fowler et al.12B • 1963 by Wilkinson et al.12B/12N • 1966 by Schwalm 12B/12N b-decay approach 0.000044(15) (2+) 15.11 (15.3) 1+ 0.0031(12) 1+ 12.71 0.0046(15) (2+) (11.5) 0.0008(2) 10.3 0,2+ 0.027(4) 0.015(3) 7.6542 0+ 7.275 0.0190(3) 0.0125(5) 4.4389 2+ 0.946(6) 0.972(3) 0 0+

  10. Before introduction of solid state detectors and multi-channel analyzers

  11. A ghosts enters.. -decay nucleus Amy Bartlett’s talk

  12. One of first uses of solid state detectors and multi-channel analyzers Since 1963 no one has seen or heard of this ghost ?

  13. Illustrations from I. Gergely Ph.D. thesis

  14. 12N/12B+X a,b 12N/12B+X ISOL 12N/12B a,b How to measure b-decay? Previous

  15. ISOL beams of 12N and 12B in Europe IGISOL @ JYFL ISOLDE @ CERN : 12N @ IGISOL : 12B @ ISOLDE

  16. CERN Conseil Européen pour la Recherche Nucléaire 1GeV p

  17. Experiments 2001-2002 12N/12B Reduced dead-layer Bergmann, Fynbo & Tengblad NIMA515 (2003) 657. Tengblad, Bergmann, Fraile, Fynbo & Walsh, NIMA525 (2004) 458.

  18. The b-decay of 12N

  19. 1 8Be s 12N decay to 12C - 3a events

  20. The b-decay of 12B

  21. 12B decay to 12C - 3a events C. Diget PhD

  22. Interpretation of results

  23. Combined fit of12Band 12N • Select 8Be 0+ channel • Divide by different detection efficiency • Divide by different-phase space • Normalize

  24. Result of combined fit 473 d.o.f. 4.2(2) 4.36(17) Relative contribution of “Ghost” and higher state varies with channel radius “a” (no absolute normalization) E(0+) = 10.73(3) MeV (0+) = 1.72(2) MeV E(2+) = 13.7(1) MeV (2+) = 1.9(3) MeV Work performed by F.C. Barker C. Diget et al. NPA760 (2005) 3.

  25. 12C New experiments 10 0+ Ghost 7.6 0+ 3 • What is the nature of the high energy state ? • Decays via 8Be (2+) ? • Measure branch to 7.65MeV state  • Relative contribution of “ghost” and “10MeV” state ? • Is the correction for detection efficiency correctly done ? • Branching ratios and Gamow-Teller strength ? • New ISOL experiment 2004 • Experiment by implantation method 2006 4.4 2+ 0 0+

  26. New ISOL experiment 2004 12N & 12B @ IGISOL

  27. Experiment 2004 L.M. Fraile & J.Äystö, NIMA513 (2003) 287. 12N/12B • Sensitive to 8Be 2+ channel

  28. 2004 data 12N 2001 12N 2004 C. Diget PhD

  29. 2004 data B.R. ~ 3 . 10-6 12B 2002 12B 2004 C. Diget PhD

  30. Compare 12Nand12B in new data Select 8Be channel Divide by different -phase space Same detection eff. Normalize As in “old” data 8Be 0+ New - not in “old” data 8Be 2+

  31. 2-2.5MeV 2-2.5MeV 7.5-8MeV 7.5-8MeV Also Dalitz plot for correlations l=0,2 l=2 12C(0 12)  8Be(2+)+  3 Spin-determination by 8Be (2+) ? ~10% of breakup

  32. KVI Groningen 10 0+/2+ 7.6 Ghost 0+ 3 4.4 2+ 0 0+ 12C • Measure branch to 7.65MeV state  Relative contribution of “ghost” and “10MeV” state ? • Is the correction for detection efficiency correctly done ? • Branching ratios and Gamow-Teller strength ? • What is the nature of the high energy state ?

  33. Method 12N/12B+X p/d ISOL 12C/11B 12N/12B b 12N/12B -Inv.kin. -Separator -Implantation 12N/12B+X p/d ab 12C/11B

  34. Setup • 4848 strip DSSD • 1616mm2 size • KU-Leuven (R.Raabe)

  35. Data from the week before Easter

  36. Data from the week before Easter

  37. First results 96.20(10) 98.16(4) 0.53(3) 1.26(6) 0.106(5) 0.52(3) 0.119(6) 2.95(15)10-4

  38. What have we learned ? • There is no low energy 2+ state in 12C populated in the 12B and 12N -decays. • The “Ghost” of the 7.6MeV state is needed to understand the “10 MeV” state, which has spin 0+. • The “10 MeV” state mainly decays to the 8Be ground state and its “ghost”, but also to 8Be 2+. • There is a new (2+) state above 14MeV in12C populated in the 12N (and 12B) -decays. • The branching ratios are now much better known.

  39. The 3-rate C. Diget

  40. Interpretation three peaks 3.1MeV 2+ 0.93MeV 0+ 8Be

  41. Breakup of the 12.71 MeV state in 12C R-matrix based Sequential breakup Faddeev equations In momentum space Hyper spherical Harmonics expansion. Sov. J. Nucl. Phys. 52 (1990) 827 Phys. Rev. C10 (1974) 975 Phys Rev C16 (1977) 529

  42. 12.71 MeV 1+ state - breakup Sequential without Interference Sequential with Interference Direct B.Blank’s talk Fynbo et al. PRL 91 (2003) 82502.

  43. 10B+3Hep+12C* + 8Be CMAM Madrid Monte-Carlo data from April 2005 New data March 2006 Data

  44. M. Alcorta, R. Boutami, M.J.G. Borge, M. Madurga Flores, O. Tengblad, • M. Turrion, Instituto Estructura de la Materia, CSIC, Madrid, Spain + CMAM operators • B. Jonson, M. Meister, T. Nilsson, G. Nyman, K. Wilhelmsen, • Fundamental Physics, Chalmers University of Technology, Gothenburg,Sweden Collaborators • C. Aa. Diget, H. Fynbo, H. Jeppesen, S.G. Pedersen, K. Riisager, • Department of Physics and Astronomy, Århus University, Denmark • T. Eronen, W. Huang, J. Huikari, A. Jokinen, P. Jones, A. Kankainen, I. Moore, • A. Nieminen, H. Penttilä, S. Rinta-Anttila, Y. Wang, J. Äystö, A. Saatamoinen, • K. Perajärvi, Department of Physics, University of Jyväskylä, Finland • U.C. Bergmann, J. Cederkäll, L.M. Fraile, S. Franchoo, L. Weissman • ISOLDE, EP-Division, CERN, Geneva, Switzerland • B. Fulton, S.Fox • University of York, United Kingdom. Thank you for your attention ! • F.C. Barker • Australian National University • K. Jungmann, S. Brandenburg, H. Wilschut, P. Dendooven, A. Rogachevskiy, • G. Onderwater, E. Traykov, M. Sohani, KVI, Groningen, The Netherlands • R. Raabe, J. Bücherer, Piet van Duppen, Mark Huyse, IKS, Leuven, Belgium

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