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Bindungsenergie: (semi-) empirische Massenformel von Bethe-Weizsäcker

Bindungsenergie: (semi-) empirische Massenformel von Bethe-Weizsäcker. 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. 1898 Polonium (Z=84) Radium (Z=88).

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Bindungsenergie: (semi-) empirische Massenformel von Bethe-Weizsäcker

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  1. Bindungsenergie: (semi-) empirische Massenformel von Bethe-Weizsäcker B = av A - as A2/3 - ac Z(Z-1)A-1/3 - asym (A-2Z)2/A  ap A-3/4 Volumen Oberfläche Coulomb Symmetrie Paarung

  2. 1898 Polonium (Z=84) Radium (Z=88) 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 1899 Actinium (Z=89) 1908 Radon (Z=86) 1917 Protactinium (Z=91) 1939 Francium (Z=87) 1896 Discovery of radioactivity by A.H. Becquerel Radioactivity period 1896 1940 1941 Plutonium (Z=94) 1950 Californium (Z=98) 1940 Astatin (Z=85) Neptunium (Z=93) 1939 60-inch-cyclotron group: Cooksey, Corson, Ernest O. Lawrence Thornton, Backus, Salisbury, Luis Alvarez und Edwin McMillan 1944 Americium (Z=95) Curium (Z=96) 1949 Berkelium (Z=97) Neutron period 1940 1952 1955 Mendelevium (Z=101) 1970 Dubnium (Z=105) 1965 Nobelium (Z=102) Lawrencium (Z=103) 1952 Einsteinium (Z=99) Fermium (Z=100) 1974 Seaborgium (Z=106) 1969 Rutherfordium (Z=104) Synthesis of SHE via hot fusion of heavy target nuclei with light projectiles 1952 1974 1982 Meitnerium (Z=109) The linear accelerator UNILAC and the velocity filter SHIP at GSI allowed for the synthesis of elements with Z=107-112. 1994 Element 110 Element 111 1996 Element 112 1981 Bohrium (Z=107) 1984 Hassium (Z=108) Synthesis of SHE via gentle fusion (Pb and Bi as target nuclei) 1974 1996 History of the synthesis and discovery of super heavy elements (SHE) With Fermi’s 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). (P. Armbruster, “Spektrum der Wissenschaft“, Dezember 1996)

  3. The Limits of Stability Island of stability ? stabilisationvia shelleffects Z = 100 liquid dropmodel

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

  5. region der spherically shell stabilised nuclei („island of stability“) 208Pb region of deformed shell stabilised nuclei around Z=108 and N=162 Schalenkorrekturen Eshell in der Region der schweren ElementeP. Möller et al. at GSI: Elements 107-112 first synthesised and unambiguously identified 107 – Bh 108 – Hs 109 – Mt

  6. Alpha -Zerfall klassisch verboten. Quantenmechanischer Tunneleffekt

  7. α-Zerfall: Halbwertszeit vs. Q-Wert

  8. α-Zerfall: Q-Wert gegen Massenzahl

  9. Stop- und Backward-Detector Array

  10. 58Fe+209Bi  267Mt*- an Example Chain

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

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

  13. 1 second • time limits for the actual efficiency of the set-up 1 second 1 minute 1 minute 1 hour • time limits for a set-up with a 10 times improved efficiency 1 hour 1 day 1 day 10 days 10 days Time Limits for the Heavy Element Production

  14. The SHIPTRAP Project SHIP Kinematic seperator fusion of A=40 to 80 projectiles with Pb, Bi target: 0.5 mg/cm2 energy 5 A MeV intens. 2-5 1012 ions/s repetition rate 50 Hz pulse duration 6ms

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

  16. Synthesis and Identification of SHE at SHIP n 208Pb 70Zn 277112 277112 CN 11.45 MeV 280 s 273110 11.08 MeV 110  s 269Hs 9.23 MeV 19.7 s 265Sg 4.60 MeV (escape) 7.4 s 261Rf known 8.52 MeV 4.7 s 257No 8.34 MeV 15.0 s 253Fm Date: 09-Feb-1996 Time: 22:37 h 277112 kinematic separation in flight identification by - correlations to known nuclides

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