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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
Bindungsenergie: (semi-) empirische Massenformel von Bethe-Weizsäcker
1934Enrico Fermi proposes to irradiate Uranium with neutrons in order to synthesise Even heavier elements
1938Otto Hahn andFritz Straßmanndiscover the neutron-inducednuclear fission
193960-inch-cyclotron group:Cooksey, Corson, Ernest O. LawrenceThornton, Backus, Salisbury,Luis Alvarez und Edwin McMillan
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 beProduced in Berkeley (CA, U.S.A.)and in Dubna (Rußland).
The linear acceleratorUNILAC and thevelocity filter SHIP at GSI allowed for the synthesis of elements with Z=107-112.
Synthesis of SHE via hot fusion of heavy target nuclei with light projectiles1952 1974
Neutron period1940 1952
1896Discovery of radioactivity by A.H. Becquerel
Radioactivity period1896 1940
Synthesis of SHE via gentle fusion (Pb and Bi as target nuclei)1974 1996
1899Actinium (Z=89) 1908
Radon (Z=86) 1939Francium (Z=87)
1917Protactinium (Z=91)
1952Einsteinium (Z=99)Fermium (Z=100)
1940Astatin (Z=85)Neptunium (Z=93)
1944Americium (Z=95)Curium (Z=96)
1941Plutonium (Z=94)
1950Californium (Z=98)
1949Berkelium (Z=97)
1996Element 112
1994Element 110Element 111
1982Meitnerium (Z=109)
1981Bohrium (Z=107) 1984
Hassium (Z=108)
(P. Armbruster, “Spektrum der Wissenschaft“, Dezember 1996)
1969Rutherfordium (Z=104)
1965Nobelium (Z=102)Lawrencium (Z=103)
1974Seaborgium (Z=106)
1970Dubnium (Z=105)
1955Mendelevium (Z=101)
1898 Polonium (Z=84) Radium (Z=88)
History of the synthesis and discovery of super heavy elements (SHE)
208Pb
region der spherically shell stabilised nuclei(„island of stability“)
region of deformed shell stabilised nuclei around Z=108 and N=162
at GSI: Elements 107-112first synthesisedand unambiguouslyidentified
107 – Bh108 – Hs109 – Mt
Schalenkorrekturen Eshell in der Region der schweren Elemente
P. Möller et al.
SHE Cross Section Systematic (1n ER Reactions)
first hint for deviation from empirically observed trend from LBNL?
Xno evidence of unusual behaviour for the 1n-reactions yet
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)
•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
SHIPKinematic 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
The SHIPTRAP Project
The SHIPTRAP Project
Combined In-Flight and ISOL facility for fusion products
Mass measurements for * trans-uranium elements * N=Z nuclei
Gas cell
RFQ coolerand buncher Penning trap
known
CN277112
273110
269Hs
265Sg
261Rf
257No
11.45 MeV280 s
11.08 MeV110 s
9.23 MeV19.7 s
4.60 MeV (escape)7.4 s
8.52 MeV4.7 s
253Fm8.34 MeV15.0 s
Date: 09-Feb-1996Time: 22:37 h
277112
70Zn 208Pb 277112
n
kinematic separationin flight identification
by - correlationsto known nuclides
Synthesis and Identification of SHE at SHIP