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Adam Maj IFJ PAN Krakow

Adam Maj IFJ PAN Krakow. Search for Pigmy Dipole Resonance in 68 Ni RISING experiment in GSI. EWON Meeting Prague, 10-12 May, 2007. RISING R are IS otope IN vestigation at G SI. The Accelerators: UNILAC ( injector) E<11.5 MeV/n SIS 18Tm corr. U 1 GeV/n

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Adam Maj IFJ PAN Krakow

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  1. Adam Maj IFJ PAN Krakow Search for Pigmy Dipole Resonance in 68Ni RISING experiment in GSI EWON Meeting Prague, 10-12 May, 2007

  2. RISINGRare ISotope INvestigation at GSI • The Accelerators: • UNILAC(injector) E<11.5 MeV/n • SIS 18Tmcorr. U 1 GeV/n • Beam Currents: 108 - 109 pps • FRS --> secondary radioactive ion beams: • Fragmentation or fission of primary beams • High secondary beam energies: • 100 – 700 MeV/u • Fully stripped ions • Reactions on a secondary target • Implantation inside a stopper • Nuclear structure of exotic nuclei studied bySecondary fragmentation and Relativistic Coulomb excitation • g-factor measurements • Isomeric gamma and beta decay studies

  3. EUROBALL Cluster Detectors Beam Tracking system Why at FRS@GSI ? • Unique European facility for relativistic (b ≥ 0.4) exotic beams • lifetime range ≥100 ns • fully stripped beams • Spin Aligned beams + Miniball – Hector

  4. Fast Beam Campaign (2003-2005) g-factor campaign (2005) – cf. D. Balabanski talk Stopped beam campaign (running) EUROBALL Cluster Detectors Beam Tracking system + Miniball – Hector

  5. Fast Beam Campaign (2003-2005) EUROBALL Cluster DetectorsMiniball: HPGe segmented detectors HECTOR Large 14.5 x 17 cm BaF2 Detectors CATE : E-DE telescope event by event beam identification Coulomb Excitation at Relativistic Energy • Relativistic Coulomb excitation of nuclei near 100Sn • New Shell structure at N>>Z • Mirror symmetry of new (sub)shell closures : 36S – 36Ca • Triaxiality in even-even core nuclei of N=75 isotones • E1 Collectivity in neutron rich nuclei 68Ni

  6. Cross-section for electromagnetic excitations

  7. GDR and PDR N N Average Transition charge densities P Richter NPA 731(2004)59 Richter NPA 731(2004)59 Average Transition charge densities

  8. g-decay of the Giant and Pigmy Dipole Resonaces Excited via relativistic Coulomb Excitation PDR have large impact on understanding of the r-process nucleosynthesis (S. Goriely. Phys. Lett.B436 (1998) 1)

  9. 48Ca 40Ca Adrich et al. PRL 95(2005)132501 T. Hartmann PRL85(2000)274 Question: How collective properties changes moving to neutron rich nuclei? Dipole strength shifts at low energy Collective or non-collective nature of the transitions? Stable nuclei  photoabsorption Exotic nuclei Virtual photon breakup LAND experiment Virtual photon scattering RISING experiment

  10. Incoming 68Ni beam 68Ni AoQ Z Coulomb excitation of 68Ni (600 MeV A) Outgoing 68Ni E (CsI) 1.2 % 4.4 % DE (Si) ~ 6 Days of effective beam time ~ 400 GB of data recorded ~ 3 107 ‘ good 68Ni events ‘ recorded

  11. Coulomb excitation of 68Ni (600 MeV A) Pygmy Dipole Resonance ? Preliminary Preliminary Preliminary Red lines – GEANT4 simulation assuming 10.8 MeV monoenergetic transition A structure appears at 10-11 MeV in all detector types A. Bracco et al., Acta Phys. Pol.B38, 1229 (2007), F. Camera et al., to be published

  12. CONCLUSIONS RPA RMF 68Ni 68Ni ~10 MeV ~10 MeV G. Colo private communications D. Vretnar et al. NPA 692(2001)496 • Both RPA and RMF approaches predict for 68Ni Pygmy strength at approximately 10.8 MeV for 68Ni • The degree of collectivity is still debated

  13. COLLABORATION: Milano:A. Bracco,F. Camera, O. Wieland, G. Benzoni, S. Leoni, B. Million,… Kraków: P. Bednarczyk, J. Grębosz, M. Kmiecik, A. Maj, K. Mazurek, W. Męczyński, J. Styczeń GSI: T. Aumann, H.J. Wollersheim, J. Gerl, I. Kojouharow,…. Legnaro: G. de Angelis, A. Gadea, D. Napoli,.. Sofia/Camerino: D. Balabanski

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