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The perspectives of nuclear astrophysics at fragmentation facilities

The perspectives of nuclear astrophysics at fragmentation facilities. Klaus Sümmerer, GSI Darmstadt. Nuclear physics input to astrophysics: e.g. Nuclear structure: Masses, decay half lives, level properties, GT strengths, shell closures etc. Reaction rates for capture reactions

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The perspectives of nuclear astrophysics at fragmentation facilities

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  1. The perspectives of nuclear astrophysics at fragmentation facilities Klaus Sümmerer, GSI Darmstadt • Nuclear physics input to astrophysics: e.g. • Nuclear structure: Masses, decay half lives, level properties, GT strengths, shell closures etc. • Reaction rates for capture reactions • Isospin and density dependence of the nuclear equation of state • Contributions from fragmentation-type facilities: • Spectroscopy of stopped fragments • Unique storage-ring experiments • Break-up reactions of unstable nuclei

  2. Nuclear-structure information from fragmentation facilities • Experiments with stopped fragments: • Combines production/separation at high energy with experiments at low energy • High energy  thick degrader  high isotopic purity • Complementary to ISOL: • Access to refractory elements not available from ISOL • Access to very short half lives • Future (GSI/RIA): Access to N=126 r-process waiting-point nuclei and fissile nuclei below 238U

  3. Super-FRS: low-energy branch

  4. Predicted production rates at Super-FRS

  5. Storage-ring experiments • Mass/half life measurements at storage rings: • Mass measurements over large areas of the nuclear chart • Resolution of isomers • Access to very short half lives (TOF method) • Half life measurements for ionized species (e.g. BBD) • Scattering and transfer reactions at internal target: • (p,n) to measure GT strengths • (, ’) to measure giant monopole resonance (EOS of asymmetric nuclear matter)

  6. Super-FRS: Ring branch • Mass and half life measurements • Scattering and transfer Electron scattering Short half lives, stochastic cooling Long half lives, electron cooling, nuclear reactions H.Weick, H.Simon et al.

  7. Excitation of Giant Monopole Resonances to determine the nuclear compressibility of asymmetric nuclear matter • GMR excitations in (, ’) reactions: • measure near cm=0 degree • E  1 MeV • possible only in storage ring! • wide range of A/Z • E.g. 104-132Sn E/A=400 MeV, 1014 He atoms/cm2

  8. Reaction-rate measurements at fragmentation facilities Measure rad.capture reaction (p/n, ) via Coul.diss. (,p/n) • Advantages of inverse measurements: • Access to short-lived species • Thick targets  access to rare species • Coincident detection of fast particles  low background • Disadvantages of inverse measurements: • Connects only ground states • Different sensitivity to multipolarities • Small Q-values • Recent examples: • 7Be(p,)8B (GSI) • 8B(p,)9C (RIKEN) • 14C(n,)15C (GSI)

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