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

2. Historic Introduction 1953 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 0 4.4 7.6 10 E in MeV 0+0+ 2+2+ 0+0+ 0 + /2 + Hoyle Fowler Morinaga 33 12 C

3. B 2 FH 1956 Hoyl e Fowler 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 2 + ? 10.3 Bold conjecture shortly after work of Aa.Bohr on rotational motion Ongoing theoretical interest : Ab-initioPieper, NP A751 (2005) 516. AMD Kanada En’yo, PRL 81 (1998) 5291 FMD Feldmeier SMNavratil, Vary & Barrett, PRL 84 (2000) 5728 U( +1) groupBijker & Iachello, PRC61 (2000) 67305 Cluster too many to do justice  S.Courtin’s talk  Charissa collab.

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

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

7. Why it isn’t all known

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

9.  -decay approach (11.5) 0,2 + 0+0+ 10.3 7.6542 12.71 1+1+ 15.11 1+1+ 7.275 (2 + ) (15.3) 4. 4389 0 2+2+ 0+0+ 0.972(3) 0.0125(5) 0.015(3) 0.0008(2) 0.946(6) 0.0190(3) 0.027(4) 0.0046(15) 0.0031(12) 0.000044(15)  -decay measured: 1950 by Alvarez 12 N 1957 by Fowler et al. 12 B 1963 by Wilkinson et al. 12 B/ 12 N 1966 by Schwalm 12 B/ 12 N

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

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

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

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

14. How to measure  -decay? Previous 12 N/ 12 B+X ISOL  12 N/ 12 B  12 N/ 12 B+X

15. IGISOL @ JYFL ISOLDE @ CERN 2001: 12 N @ IGISOL 2002: 12 B @ ISOLDE ISOL beams of 12 N and 12 B in Europe

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

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

19. The  -decay of 12 N

20. 12 N decay to 12 C - 3  events 8 Be  s 11

21. The  -decay of 12 B

22. 12 B decay to 12 C - 3  events C. Diget PhD

23. Interpretation of results

24. Combined fit of 12 B and 12 N 1. Select 8 Be 0 + channel 2. Divide by different detection efficiency 3. Divide by different  -phase space 4.Normalize

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

26. New experiments What is the nature of the high energy state ? Decays via 8 Be (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 0 4.4 7.6 10 0+0+ 2+2+ 0+0+ 0+0+ 33 12 C Ghost

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

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

29. 12 N 2001 12 N 2004 2004 data C. Diget PhD

30. 12 B 2002 12 B 2004 2004 data B.R. ~ 3. 10 -6 C. Diget PhD

31. 8 Be 0 + 8 Be 2 + Select 8 Be channel Divide by different  -phase space Same detection eff. Normalize Compare 12 N and 12 B in new data New - not in “old” data As in “old” data

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

33. KVI Groningen 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 ? 0 4.4 7.6 10 0+0+ 2+2+ 0+0+ 0 + /2 + 33 12 C Ghost

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

35. Setup 48  48 strip DSSD 16  16mm 2 size KU-Leuven (R.Raabe)

36. Data from the week before Easter

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

39. What have we learned ? There is no low energy 2 + state in 12 C populated in the 12 B and 12 N  -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 8 Be ground state and its “ghost”, but also to 8 Be 2 +. There is a new (2 + ) state above 14MeV in 12 C populated in the 12 N (and 12 B)  -decays. The branching ratios are now much better known.

40. The 3  -rate C. Diget

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

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

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

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

45. Collaborators C. Aa. Diget, H. Fynbo, H. Jeppesen, S.G. Pedersen, K. Riisager, Department of Physics and Astronomy, Århus University, Denmark U.C. Bergmann, J. Cederkäll, L.M. Fraile, S. Franchoo, L. Weissman ISOLDE, EP-Division, CERN, Geneva, Switzerland B. Jonson, M. Meister, T. Nilsson, G. Nyman, K. Wilhelmsen, Fundamental Physics, Chalmers University of Technology, Gothenburg, Sweden 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 B. Fulton, S.Fox University of York, United Kingdom. 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 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