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B = a v A - a s A 2/3 - a c Z(Z-1)A -1/3 - a sym (A-2Z) 2 /A a p A -3/4 Volumen Oberfläche Coulomb Symmetrie Paarung Bindungsenergie: (semi-) empirische.

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Presentation on theme: "B = a v A - a s A 2/3 - a c Z(Z-1)A -1/3 - a sym (A-2Z) 2 /A a p A -3/4 Volumen Oberfläche Coulomb Symmetrie Paarung Bindungsenergie: (semi-) empirische."— Presentation transcript:

1 B = a v A - a s A 2/3 - a c Z(Z-1)A -1/3 - a sym (A-2Z) 2 /A a p A -3/4 Volumen Oberfläche Coulomb Symmetrie Paarung Bindungsenergie: (semi-) empirische Massenformel von Bethe-Weizsäcker

2 1934 Enrico Fermi proposes to irradiate Uranium with neutrons in order to synthesise Even heavier elements 1938 Otto Hahn and Fritz Straßmann discover the neutron-induced nuclear fission inch-cyclotron group: Cooksey, Corson, Ernest O. Lawrence Thornton, Backus, Salisbury, Luis Alvarez und Edwin McMillan With Fermis method and the 60-cyclotron 7 Transurane could (Z=93-98) Be synthesised. By irradiation of actinides with light ions the elements up Z=106 could be Produced in Berkeley (CA, U.S.A.) and in Dubna (Rußland). The linear accelerator UNILAC and the velocity filter SHIP at GSI allowed for the synthesis of elements with Z= Synthesis of SHE via hot fusion of heavy target nuclei with light projectiles Neutron period Discovery of radioactivity by A.H. Becquerel Radioactivity period Synthesis of SHE via gentle fusion (Pb and Bi as target nuclei) Actinium (Z=89) 1908 Radon (Z=86) 1939 Francium (Z=87) 1917 Protactinium (Z=91) 1952 Einsteinium (Z=99) Fermium (Z=100) 1940 Astatin (Z=85) Neptunium (Z=93) 1944 Americium (Z=95) Curium (Z=96) 1941 Plutonium (Z=94) 1950 Californium (Z=98) 1949 Berkelium (Z=97) 1996 Element Element 110 Element Meitnerium (Z=109) 1981 Bohrium (Z=107) 1984 Hassium (Z=108) (P. Armbruster, Spektrum der Wissenschaft, Dezember 1996) 1969 Rutherfordium (Z=104) 1965 Nobelium (Z=102) Lawrencium (Z=103) 1974 Seaborgium (Z=106) 1970 Dubnium (Z=105) 1955 Mendelevium (Z=101) 1898 Polonium (Z=84) Radium (Z=88) History of the synthesis and discovery of super heavy elements (SHE)

3 liquid dropmodel stabilisation via shelleffects Z = 100 Island of stability ? The Limits of Stability

4 Synthese von Element 107 Kalte Fusion: Erzeugung eines Verbundkerns mit geringer Anregungsenergie

5 208 Pb region der spherically shell stabilised nuclei (island of stability) region of deformed shell stabilised nuclei around Z=108 and N=162 at GSI: Elements first synthesised and unambiguously identified 107 – Bh 108 – Hs 109 – Mt Schalenkorrekturen E shell in der Region der schweren Elemente P. Möller et al.

6 Alpha -Zerfall klassisch verboten. Quantenmechanischer Tunneleffekt

7 α-Zerfall: Halbwertszeit vs. Q-Wert

8 α-Zerfall: Q-Wert gegen Massenzahl

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11 Stop- und Backward-Detector Array

12 58 Fe+ 209 Bi 267 Mt * - an Example Chain

13 SHE Cross Section Systematic (1n ER Reactions) first hint for deviation from empirically observed trend from LBNL? X no evidence of unusual behaviour for the 1n-reactions yet

14 deviation from empirically observed trend at the FLNR (Dubna) 1pb SHE Cross Section Systematic (xn ER Reactions) cold fusion (Pb and Bi targets) hot fusion (actinide targets)

15 time limits for the actual efficiency of the set-up 10 days 1 minute 1 hour 1 day 1 second time limits for a set-up with a 10 times improved efficiency 10 days 1 minute 1 hour 1 day 1 second Time Limits for the Heavy Element Production

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24 SHIP Kinematic seperator fusion of A=40 to 80 projectiles with Pb, Bi target: 0.5 mg/cm 2 energy 5 A MeV intens ions/s repetition rate 50 Hz pulse duration 6ms The SHIPTRAP Project

25 Combined In-Flight and ISOL facility for fusion products Mass measurements for * trans-uranium elements * N=Z nuclei Gas cell RFQ cooler and buncher Penning trap

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28 known CN Hs 265 Sg 261 Rf 257 No MeV 280 s MeV 110 s 9.23 MeV 19.7 s 4.60 MeV (escape) 7.4 s 8.52 MeV 4.7 s 253 Fm 8.34 MeV 15.0 s Date: 09-Feb-1996 Time: 22:37 h Zn 208 Pb n kinematic separation in flight identification by - correlations to known nuclides Synthesis and Identification of SHE at SHIP


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