1 / 25

-capture measurements with a Recoil-Separator

-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. 12 C( ,) 16 O the Holy Gral of

Download Presentation

-capture measurements with a Recoil-Separator

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. -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 15th – 21st January 2006, Hirschegg, Austria

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

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

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

  5. g-Recoil Coincidences Separation Detection & Identification projectiles Recoils + Recoils projectiles focusing prec = pproj momentum conservation g-ray emission  Recoil cone ERNA - Experimental approach He target projectiles Minimum supression factor with s = 10nbarn, ntarget=1x1018at/cm² Nproj / Nrecoils~ 1x1014

  6. ERNA - Experimental approach Setup ion source dynamitrontandem accelerator recoil focussing D E - E telescope He magnetic Gastarget Wien filter qu adrupole multiplets analysing doublet triplet magnet singlet ion beam Wien filter purification Wien filter side 60° magnet Wien filter FC recoil separation

  7. characteristics: • angular acceptance  32 mrad for 16O at Elab=3.0 – 15.0MeV for the total length of the gas target • energy acceptance  10% for 16O at Elab=3.0 – 15.0 MeV • suppression of incident beam (10-10 - 10-12)·10-2 (IC) => smin< 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

  8. ERNA - Experimental approach Setup Gas target Gas pressure profile: 7Li(a,g)11B, 7Li(a,a)7Li + energy loss of: 14N, 12C, 7Li

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

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

  11. ERNA Motivation Helium Burning Stellar Helium burning: 12C(a,g)16O Main reactions: 3a12C and 12C(a,g)16O 4He Red Giant 12C/16O abundance ratio triple alpha 12C Subsequent stellar evolution and nucleosynthesis 4He 12C(a,g)16O but 16O E0~ 300 keV, very low cross section Accurate measurements at higher energy and extrapolation to E0 are needed

  12. ERNA E/E Matrix 12C(a,g)16O Ecm=2.5 MeV SuppressionR~8*10-12

  13. ERNA Cross Section Curve RESULTS

  14. ERNA astrophysical S Factor RESULTS

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

  16. ERNA Motivation Neutrino Spectroscopy

  17. ERNA Motivation Neutrino Spectroscopy Influence of different sources of uncertainties on the neutrino flux D(L  ) = 0.4 % D(age ) = 0.4 % D(Z/H ) = 3.3 % D(p-p) = 2 % D(3He+3He) =6 % D(3He+4He) =15 % D(7Be+p) = 10 %

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

  19. Jp Ex (keV) 4570 7/2- DC  429 Q = 1587keV 3He+4He 429 1/2- DC  0 g EC Jp 0 3/2- Ex (keV) 7Be level scheme g 1/2- 428 Gamma: S34(0) = 0.507±0.016 keVb Activation: S34(0) = 0.563±0.018 keVb 3/2- 0 7Li ERNA Motivation 3He(,)7Be 3He(a,g)7Be(e,n)7Li*(g)7Li

  20. ERNA Acceptance 3He(,)7Be

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

  22. ERNA astrophysical S Factor RESULTS Preliminary result

  23. ERNA – present status • 12C(,g)16O Ecm>1.9 MeV (1.3 MeV) • 3He(a,g)7Be Ecm>1.1 MeV (0.6 MeV) ERNA - future plans and other perspectives • 14N(p,g)15O • 16N b-delayed -decay • 14N(a,g)18F • d(a,g)6Li

More Related