1.  -capture measurements with a Recoil-Separator Frank Strieder Institut für Physik mit Ionenstrahlen Ruhr-Universität Bochum Int. Workshop on Gross Properties of Nuclei and Nuclear Excitation 15 th – 21 st January 2006, Hirschegg, Austria

2. 12 C( ,  ) 16 O the Holy Gral of Nuclear Astrophysics e e 3 He( ,  ) 7 Be pp chain

3. ErEr DANGER OF EXTRAPOLATION ! non resonant process interaction energy E extrapolation or measurements ? direct measurement 0 S(E) LINEAR SCALE S(E)-FACTOR -E r sub-threshold resonance low-energy tail of broad resonance Danger of Extrapolation Important for Experiments Low energy High energy

4. ERNA - Experimental approach Pro & Cons purification separation A B C n+ detection A  coincidence detection Requirements beam purification 100% transmission for the selected charge state high suppression of the incident beam inverse kinematics (gas target) Advantages low background high detection efficiency measure  tot background free  ray spectra gas target Disadvantages difficult to do commissioning charge state beam intenity ? A different approach: recoil mass separator C

5. ERNA - Experimental approach projectiles + Recoils p rec = p proj momentum conservation Separation Detection & Identification Recoils projectiles focusing He target  -ray emission  Recoil cone  -Recoil Coincidences Minimum supression factor with  = 10nbarn, n target =1x10 18 at/cm² N proj / N recoils ~ 1x10 14

6. ERNA - Experimental approachSetup ion source dynamitron tandem accelerator ion beam purification He Gastarget singlet 60° magnet  E-E telescope recoil separation doublet analysing magnet recoil focussing Wien filter magnetic quadrupole multiplets triplet side FC

7. characteristics:  angular acceptance  32 mrad for 16 O at E lab =3.0 – 15.0 MeV for the total length of the gas target  energy acceptance  10% for 16 O at E lab =3.0 – 15.0 MeV  suppression of incident beam (10 -10 - 10 -12 )·10 -2 (IC) =>  min < 1 nb  purification of incident beam < 10 -22  resolution of ion chamber  250·A keV or combination  E-silicon strip detector  layout COSY Infinity (recoils fit in 4” beam tube)  field settings are not calculated, but tuned

10. ERNA - Experimental approach Setup Gas target Gas pressure profile : 7 Li(  ) 11 B, 7 Li(  ) 7 Li + energy loss of: 14 N, 12 C, 7 Li

11. ERNA - Experimental approach Charge State Distributions measured for entire energy range but question about point of origin in the gas target → no equilibrium 4 He gas 12 C beam

12. ERNA - Experimental approach Setup Solution: a post-target-stripper to the separator ► First test with laser ablated carbon foil: 12 C( 12 C, 8 Be) 16 O ► Final configuration: Ar post-target stripper after the 4 He target 4 He Ar 3 He( ,  ) 7 Be no post-target-stripper – measure all charge states

13. Angular acceptance along the gas target ERNA - Experimental approach Setup 4 He gas 12 C beam separator central position upstream position beam diameter upstream position (energy acceptance) full angular acceptance  100 % transmission (better 3  ) over the total gas target length and full beam diameter

14. Angular acceptance along the gas target ERNA - Experimental approach Setup - + Simulation of recoil cone

15. 12 C( ,  ) 16 O: E cm =1.3 MeV  rec = 26 mrad,  E/E = 10.8 %,  ≈ 150 pb ERNA - Experimental approach Angular Acceptance

16. Angular acceptance along the gas target Energy acceptance Change beam energy -20-15-10-505101520 0.0 0.2 0.4 0.6 0.8 1.0 transmission  E / E 0 [ % ] experimental calculated ERNA - Experimental approach Setup

17. ERNA Motivation Helium Burning Main reactions: 3  12 C and 12 C(  ) 16 O Stellar Helium burning: 12 C(  ) 16 O 12 C/ 16 O abundance ratio Subsequent stellar evolution and nucleosynthesis but E 0 ~ 300 keV, very low cross section Accurate measurements at higher energy and extrapolation to E 0 are needed 12 C 4 He 16 O 4 He triple alpha 12 C(  ) 16 O Red Giant

18. 12 C( ,  ) 16 O – Level Scheme ERNA  -ray spectroscopy low efficiency cosmic background angular Distributions target stability The 12 C( ,  ) 16 O reaction Complications: two subthreshold states dominate S(E)-factor at Gamow peak interference effects how to extrapolate? stellar energy window 12 C+ 4 He 16 O T ~ 3 x 10 8 K E cm (keV) E x (keV) JJJJ E1E2  ~ 1pb important for evolution of 20-25 M  stars rate needed to ± 10% ! at Gamow peak (E ~ 300 keV) estimated cross section  ~ 10 -17 barn ! prohibitively small to be measured directly

19. ERNA  E/E Matrix 12 C(  ) 16 O E cm =2.5 MeV Suppression R~8*10 -12

20. ERNA  E/E Matrix E cm =4.4 MeV E cm =3.5 MeV E cm =3.2 MeV E cm =2.0 MeV  (literature) ≈ 10 nb  (literature) ≈ 0.8  b

21. ERNACross Section CurveRESULTS

22. ERNAastrophysical S FactorRESULTS

23. ERNA  -ray measurementsRESULTS ground state transition cascades via 7.12 and 6.92 MeV 16 O coincidences background ( 12 C coincidences) offresonance

24. ERNA Motivation Helium Burning solar spy = solar neutrinos Neutrino spectroscopy ? Sun = calibrated source

25. ERNA Motivation Neutrino Spectroscopy

26.  (L  ) = 0.4 %  age  ) = 0.4 %  Z/H  ) = 3.3 %  (L  ) = 0.4 %  age  ) = 0.4 %  Z/H  ) = 3.3 %  p-p) = 2 %  3 He+ 3 He) = 6 %  3 He+ 4 He) = 15 %  7 Be+p) = 10 %  p-p) = 2 %  3 He+ 3 He) = 6 %  3 He+ 4 He) = 15 %  7 Be+p) = 10 % Influence of different sources of uncertainties on the neutrino flux

27. ERNA Motivation Neutrino Spectroscopy Influence of different sources of uncertainties on the neutrino experiment

28. ERNA Motivation 3 He( ,  ) 7 Be 3 He( ,  ) 7 Be p + p  d + e + + e d + p  3 He +  3 He + 3 He   + 2p 3 He + 4 He  7 Be +  7 Be+e -  7 Li +  + e 7 Be + p  8 B +  7 Li + p   +  8 B  2  + e + + e 84.7 %13.8 % 13.78 % 0.02 % pp Kette important for: - precise determination of solar neutrino flux - cosmology – BBN nucleosynthesis

29. ERNA Motivation 3 He( ,  ) 7 Be Gamma: S 34 (0) = 0.507±0.016 keVb Activation: S 34 (0) = 0.563±0.018 keVb E x (keV) JJ 4570 429 0 7/2 - 1/2 - 3/2 - 3 He+ 4 He 7 Be level scheme Q = 1587keV DC  429 DC  0  428 E x (keV) 7 Li 0 EC 1/2 - 3/2 - JJ  3 He (  ) 7 Be ( e, ) 7 Li *(  ) 7 Li

30. ERNA Acceptance 3 He( ,  ) 7 Be

31. ERNA  E/E Spectra 3 He( ,  ) 7 Be E cm =1.8 MeV Inverse kinematics

32. ERNAastrophysical S FactorRESULTS Preliminary result

33.  14 N(p,  ) 15 O  16 N  -delayed  -decay  14 N(a,  ) 18 F  d(a,  ) 6 Li ERNA - future plans and other perspectives ERNA – present status  12 C( ,  ) 16 O E cm >1.9 MeV (1.3 MeV)  3 He(a,  ) 7 Be E cm >1.1 MeV (0.6 MeV)