1. Possibilities for Nuclear Physics at the Madrid Tandem Hans O. U. Fynbo Department of Physics and Astronomy University of Aarhus, Denmark Nuclear physics and astrophysics of light nuclei A=9 and A=12 Studies at CERN of the CSIC group What could be done at a tandem?

2. Nuclear chart N = Z ?

3. A=9 and A=12 Nuclei –“Exact” A-body calculations possible for A  12 (soon) Shell-model states Molecular-cluster states –Break-up mechanism not fixed by kinematics How does three particles tunnel? Fundamental QM problem –Crucial for bridging the A=5 and A=8 gaps in Big Bang and Stellar nuclear synthesis.

4. Ab-initio Monte-Carlo calculations for A  12

5. Model Predictions (eff. Int.)

6. Some recent model predictions Nucl. Phys. A679 (2001) 393. (R. Guardiola) Resonating group calculation J. Phys. G27 (2001) 1381. Variational Calculation Phys. Rev. C62 (2000) 054311-1. Ab-initio no-core shell-model Phys. Rev. Lett. 84 (2000) 5728. Ab-initio no-core shell model Phys. Rev. C61 (2000) 0673305. U(  +1) group theory for triangular states Phys. Rev. Lett. 81 (1998) 5291. Antisymmetrised molecular dynamics (AMD) Nucl. Phys. A618 (1997) 55. Cluster model Phys. Lett. B389 (1996) 631. Coordinate space Fadeev approach. 12 C not a closed chapter of nuclear physics

7. The triple-  reaction rate

8. Break-up to Multi-particle Final States Initial state X: Some (nuclear) state Final state Y: Three (or more) particles E,  X Y : a+b+c Energy (ab) + c Direct (ab) + c Sequential 12 C * 8 Be gs +  31 Cl * 30 S+p 29 P+2p (ab) + c ? 12 C * 8 Be(2+)+  a+(bc) 9 B 8 Be+p, 5 Li+   p

9. Questions E,  E,  ? -Often difficult to Measure Spin-parity? - Selection rules The structure of the state? -Cluster states -Many-body states The mechanism of the break-up? -Sequential or direct? -Importance of different channels Relation to state structure What is : Assymptotic Spectra -Observable -Energy and angular correlations

10. 0,2 + 8 Be+  0+0+ 3-3- 1-1- 2-2- 10.27 9.641 10.3 10.84 11.83 7.6542 12.71 1+1+ 14.08 13.35 15.11 2-2- 4+4+ 1+1+ 7.377 15.9572 12 C 11 B+p 0+0+ 2+2+ 7.285  ++++ 7.285 Width  Decay  Structure E level /MeVJJ  level 8 Be (0 + ) 8 Be (2 + )7.6542(15)0+0+ 8.5(1.0) eV>96%<4% 9.641(5)3-3- 34(5) keV>96%<4% 10.3(3)0+0+ 3.0(7) MeV>90%<10% 10.849(25)1-1- 315(25)keVStrongYes 11.828(16)2-2- 260(25)keVNoYes 12.710(6)1+1+ 18.1(2.8) eVNoYes 13.352(17)2-2- 375(40)keVNoYes 14.083(15)4+4+ 258(15)keV17(4)%83(4)% 15.110(3)1+1+ 43.6(1.3) eVNoYes

11. Breakup of the 12.71MeV state Balamuth, Zurmuhle and Tabor Phys. Rev. C10 (1974) 975 A.A. Korshenninikov Sov. J. Nucl. Phys. 52 (1990) 827 R-matrix based sequential break-up with order-of-emission interference Hyperspherical Harmonics expansion. Simultaneous emission. SAME DATA !!

12. ISOLDE @ CERN

13. –Modern segmented Si-Detectors Large Solid Angle –detect all particles High Segmentation –no summing Previous studies using this setup 31 Ar 2p Nucl. Phys. A677 (2000) 38 9 C 2  p Nucl. Phys. A692 (2001) 427 12 N 3   Under analysis R.R.Betts IL NOUVO CIMENTO 110A (1997) 975 ISOL beam Low energy isotope separated beam Can be stopped in C-foil Well-defined source –Modern segmented Si-Detectors Large Solid Angle –detect all particles High Segmentation –no summing

15. L. Fraile

16. 12 C from the  -decay of 12 B Latest evaluation 1990 Region probed by  -decay 0 +, 1 +,2 + Region probed by delayed  -emission

18. Dalitz plot for 3  E1E1 E2E2 E3E3 Dalitz plot   = E  /Q   = (E  +2 E  )/Q Q

19. Simultaneous stepwise Data The 12.71MeV state: Dalitz plots Phase space E1E1 E2E2 E3E3 Dalitz plot

20. Stepwise Simultaneous

21. T  - 8 Be --  8 Be Coulomb interaction between 1 st and 2 nd emitted  s neglected !!!! PRL 20 (1968) 1178 Classical calculation No ang.mom. Included Need unphysical S  

22. Stepwise FSI Coulomb

23. Towards the Astrophysical Region 0 + state 2 + state 0 + state including interference with ghost anomaly

24. The triple-  reaction rate

25. The  -decay of 12 N Unpublished data from Heidelberg from 1978 (Schwalm) Main experimental problems are Energy loss in target Summing Evidence for new state near 13MeV

26. ”13 MeV” state Broad state “Invisible” in reaction experiments “Invisible” in single spectrum

27. Unbound states in 9 B from 9 C  -decay

28.  -decay summary Selection rules pick out specific states among possibly many (spin + isospin) Particles from breakup of unbound states fed in the decay emitted from rest Point source Thin host -> reduced energy loss Certain states cannot be produced Time structure of events can be very peaked Yield is often very limited Very restricted access to beam

29. 10 B( 3 He,p3  ) Peaks in p-spectrum  State in 12 C Peaks in  -spectrum  State in 9 B

30. 10 B( 3 He,p3  ) 10 Be( 3 He,n3  )... EE EpEp EpEp 1966

31. 6 Li( 6 Li,3  ) Reaction mechanism FSI Coulomb effects EE EE 1968

32. 9 Be ( 3 He,3  ) Reaction mechanism FSI Coulomb effects 8 Be (0 + ) EE EE 1965

33. 13 C( 3 He,4  ) Also : 7 Li (d,n  ), 10 Be( 3 He,n  ), 6 Li ( 3 He,p  ) EE EE 1965

34. Experiments at the MADRID tandem? Latest evaluation Nucl. Phys. A506 (1990) 11 B(d,p) 12 B 11 B(d,n) 12 C* 13 C( 3 He  12 C* 10 B( 3 He,p) 12 C* 11 B(p,) 12 C* P( 11 B,) 12 C* 10 B( 3 He,n) 12 N 3 He( 9 Be,) 12 C*

35. Summary To study exotic short lived nuclei new effective detector arrays have been developed New analysis methods A number of reactions suitable for tandems exist which were last visited >30 years ago. Huge potential for extracting interesting and very relevant information on light nuclei.