2 nd SPES Workshop Probing the Island of Stability with SPES beams

2 nd SPES Workshop Where are the Next Magic Shells above 208 Pb? Z = 114,120,126 N = 184 Shell closures are indicated by an increase of fission barriers and half-lives ● Nuclei with N ≈ 184 are not reachable with stable beams ● Nuclei with Z > 118 are still unknown ● The expected residue cross-sections are very low (σ << 0.1 pb)

2 nd SPES Workshop Can we probe the new Island of Stability by other means?

2 nd SPES Workshop Fusion residue cross-section: Nuclear Reactions in Heavy Systems FUSION TRANSFER, QUASI-FISSION Nuclear Molecule („quasi-nucleus“) Compound Nucleus (CN) Evaporation Residue (ER) FUSION-FISSION Fission Fragments

2 nd SPES Workshop Shell manifestation in Quasi-Fission: Potential Energy Landscape and FF/QF Paths

2 nd SPES Workshop

Evolution of FF and QF in A≈250

2 nd SPES Workshop8/31 Shell effects on the width of the QF component “Asymmetric quasifission in reactions with heavy ions” G. Knyazheva et al. “Asymmetric quasifission in reactions with heavy ions”

2 nd SPES Workshop 1.Will the capture and fusion cross-section be enhanced by increasing the neutron number of the projectile? 2.Can the binary reaction products reveal the influence of shell closure Z=120,126 and N=184? Exp. Program

2 nd SPES Workshop Reaching the Center of the Stability Valley 95 Rb Bi 96 Sr Pb → Z 1 + Z 2 = 120, N 1 + N 2 = Te Er 113 Ag Au 102 Ru Pb → Z 1 + Z 2 = 126, N 1 + N 2 = Xe Hf At Lab energies around Bass Barrier

2 nd SPES Workshop Competition FF and QF processes: Hs (Z=108)

2 nd SPES Workshop Advantages 1.Large cross sections for binary events 2.Different contact point may lead to different valleys 3.Large increase of capure cross section with increasing neutron number 4.Excitation energy can be modulated E* CN < S n ≈ 10 MeV → no neutron evaporation E* CN < B f ≈ 5 MeV → no CN fission? E* CN < 0 → no CN formation?

2 nd SPES Workshop The CORSET Spectrometer rotatable Si stop detector TOF (MCP detectors) 0.5 – 1 m ΔΩ ≈ 50 msr Si detector TOF detector ● observables: TOF, E → A, TKE ● mass resolution: ΔA / A = 1.5 %

2 nd SPES Workshop A Typical Experiment Study of quasi-fission and fusion-fission with 94,95 Rb projectiles: a)Study of the capture cross-section at three beam energies; for comparison with stable Rb ( σ capture ≈ σ QF because P CN << 1 ) b) Study of the contribution of fusion-fission reactions Projectile 94 Rb (or 85,87 Rb) 95 Rb (~2×10 6 pps) beam energy ≈ 5 MeV/u (4.0 – 5.5) MeV/u experiment Tuning of the setup Excitation functions for capture and FF ( Ϭ cap = 10 – 100) mb) shifts 6 3 x 12 Expected events(1000 – 10000) / d Target: 500 µg/cm 2, 209 Bi

2 nd SPES Workshop Probing the Island of Stability with SPES beams E. Vardaci, A. Brondi, G. La Rana, D. Pierroutsakou, P.R. Rath INFN and Dipartimento di Fisica dell’Università di Napoli, I Napoli, Italy E.M. Kozulin, G. N. Knyazheva, I.M. Itkis, K.V. Novikov, I-M. Barca Flerov Laboratory of Nuclear Reactions, JINR, Dubna S. Heinz, O. Beliuskina, T. Dickel, H. Geissel, C. Heinz, W. Plass, C. Scheidenberger, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt and Justus-Liebig-Universität, Germany

2 nd SPES Workshop 64 Ni W → 250 No 48 Ca Pb → 256 No Fission in Super-Heavy