NUCLEAR INP - NCSR D Nuclear Structure Staff: Dennis Bonatsos Students: P. Georgoudis S. Karabatsou Collaborations: N. Minkov, P.A. Terziev, INRNE Sofia D, Balabanski, U. Sofia M.N. Erduran, B. Akkus, Istanbul U. N. Casten, Yale U., N. Pietralla SUNY at Stony Brook Nuclear Reactions & Astrophysics Staff: Vivian Demetriou (since 2006) Post-doctoral researcher: D. Petrellis Collaborations: Nuclear Physics Exp. group S. Goriely, ULB, Brussels Y. El Masri, UCL, LLN Vivian Demetriou, INP, NCSR Demokritos

NUCLEAR INP - NCSR D Nuclear Structure Conferences/Workshops: International Balkan School on Nuclear Physics, Symposium of the Hellenic Nuclear Physics Society Workshop on Dynamical Symmetries 2008 Nuclear Reactions & Astrophysics Support: European Reintegration Grant (2005) on Alpha-nucleus OP Conferences/Workshops: FINUSTAR (2005), FINUSTAR 2 (2007), FINUSTAR 3 (2010)

LIBRA project Nuclear structure: study of dynamical symmetries experiment-theory Nuclear Astrophysics development of alpha-particle optical potential alpha-capture measurements theory post-doc position open for 2011

Collaborations INRNE, Sofia, Bulgaria: N. Minkov, P. A. Terziev. U. Sofia, Bulgaria / U. Camerino, Italy : D. Balabanski. Istanbul U., Turkey: M. N. Erduran, B. Akkus. SUNY at Stony Brook, USA: N. Pietralla Support: Collaborative Linkage Grant (6/2002-6/2004). New dynamic symmetries in atomic nuclei. Istanbul U. (M. N. Erduran), Bogazici U. (M. Arik), U. Sofia (D. Balabanski), NIPNE Bucharest (M. Ionescu-Bujor), NCSR Demokritos (D. Bonatsos), Yale U. (R. F. Casten). Nuclear Structure: CRITICAL POINT SYMMETRIES (2003-present)

Topics: - Sequences of potentials interpolating between U(5) and E(5) or X(5). - Davidson potentials, variational procedure. - Z(5): Solution of Bohr equation for gamma=30 deg. - Transition to octupole deformation in light actinides. - Wobbling motion within X(5). - Triaxial shapes. - Comparison between Davidson and displaced well potentials. - Derivation of collective models from rotation invariant potentials through Goldstone bosons and the Higgs mechanism. - Search for larger symmetries which could lead to X(5) through contraction.

Nuclear Reactions & Astrophysics nuclear reactions relevant to heavy-element nucleosynthesis provide cross sections and reaction rates for reaction network calculations (TALYS code) develop global and microscopic models for nuclear properties

Nuclear needs for nucleosynthesis applications Exotic species (no experimental data) Astrophysics conditions (proj. energy or target conditions not available in the Lab.)

Ground state mass, deformation, density distribution, single-particle-level scheme, … Nuclear Level Densities Fission properties: fission barriers and saddle-point NLDs Nucleon- and alpha-nucleus optical potential γ-strength function: Giant Resonance Properties Nuclear properties for cross section calculations Nuclear Ingredients from(1) direct experimental data (2) theoretical models …For about 8000 nuclei….from dripline to dripline

r process: Fission Fission paths microscopic HFB shapes (Hill-Wheeler) and WKB penetrabilities

uncertainties : B 1 MeV T 10 4 Spontaneous fission T 1/2 n-induced fission β-delayed fission Q PD, Samyn, Goriely, NPA 758 (2005),627c; Goriely, PD et al., NPA 758 (2005), 587c Work in progress: same HFB model for masses, NLDs and fission

r: ratio of maximum over minimum rates obtained with 14 different sets of nuclear ingredients using MOST Arnould and Goriely, Phys. Rep. 384, 1 (2003) neutron captures proton captures α captures p-process nucleosynthesis: n-, p- and alpha captures

αlpha radiative-capture rates low-energy cross sections depend on α-nucleus optical model potential poor knowledge of α-nucleus optical potential at energies close to Coulomb barrier optical potential determined from scattering and reaction data data at low energies are SCARCE - Square-well potential + - Woods-Saxon Double-folded real + W-S (semi-microscopic: new global OMP) accuracy reliability

Semi-microscopic alpha OP (PD, Grama and Goriely NPA 707 (2002) 253) INP Exp. Group measurements predictions

mass regions with largest uncertainties Work in progress...and Future Update existing semi-microscopic alpha OP on new data Develop fully microscopic alpha OP with RPA in close collaboration with INP Experimental Nuclear Physics group

target nuclei in (α, ) reactions studied via a 4π summing method