Study of SHE at the GSI – SHIP International School of Nuclear Physics, 30th Course Heavy-Ion Collisions from the Coulomb Barrier to the Quark-Gluon Plasma Study of SHE at the GSI – SHIP Sigurd Hofmann GSI Darmstadt and Goethe-University Frankfurt September 16-24, 2008, Erice, Sicily

SHE Calculated half-lives: 108 years – 1 ns trans-actinides spherical nuclei deformed trans-actinides actinides proton number stabile elements neutron number

Predictions of the macroscopic-microscopic model

Expected half-lives of SHE and research goals even- even Location of closed shells: Proton shell: 114, 120 or 126 / 114 – 126 ? Neutron shell: 172 or 184 ? Reaction mechanism: Cross-sections Excitation functions Cross bombardments Mass asymmetry Fusion and transfer Nuclear structure: Lifetimes Decay modes Isomers even- odd 6 3

The "UNIversal Linear ACcelerator" UNILAC Rc 1505; 2f18

Velocity separator SHIP Separation time: 1 – 2 μs Transmission: 20 – 50 % Background: 10 – 50 Hz Det. E. resolution: 18 – 25 keV Det. Pos. resolution: 150 μm Dead time: 3 – 25 μs Mastertitelformat bearbeiten

Detector system Time: F3 – F1 1 s Energy: Estop: Ebox: Position: Sistop,box – F1,2,3 4 s Sistop – Sibox 5 s Sistop,box – Ge1,2,3,4 5 s Dead time: 3 and 25 s Energy: Estop: Ebox: 0.2 – 16; 0.2 – 16 MeV 5.0 – 320; 2.5 – 160 MeV Eveto: 0.4 – 16 MeV Ge: 30 – 2000 keV 0.1 – 8.0 MeV Position: Stop x = 0 – 80 mm / 5 mm ytop,bottom = 0 – 35 mm / 0.2 mm Box: 28 Segments Fusions- Produkte

Energy versus time-of-flight plots, Δt (ER-sf) = 1000 s 252No E / MeV 206Pb 48Ca 48Ca + 206PbS => 254No* 238U 48Ca + 238U => 286112* –TOF / channel

Longest decay chain of 277112 Known nuclei 277112 CN 273110 11.45 MeV 253Fm 8.34 MeV 15.0 s yER = 17.9 mm 277112 y = 150 m (FWHM) 269108 11.08 MeV 110 s y = 35 mm 257No 8.52 MeV 4.7 s 265106 9.23 MeV 19.7 s 261104 4.60 MeV (escape) 7.4 s Known nuclei d = 300 m

First decay chain of element 112 Experiment, GSI-SHIP, 9. February 1996, 22:36 h Theory, P. Möller, 1995: Ground-state shell correction energy

Reaction mechanism Excitation functions 50Ti, 54Cr, 58Fe, 64Ni, 70Zn + 208Pb