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  • 1990-1994  (3)
  • 25.70.CD  (2)
  • 25.85.−W  (1)
  • Columnar defects  (1)
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Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Cross sections for nuclear reactions in collisions of238U+238U and238U +197Au near and below the coulomb barrier (1991)
    Springer
    The European physical journal 340 (1991), S. 303-314 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.CD ; 25.70.Lm ; 25.85.−W
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Cross sections for nuclear reactions at beam energies near and below the spherical Coulomb barrier V c were measured in the very heavy collision systems238U +238U and238U +197Au. The most probable reaction channel with mass transfer is the one-neutron transfer. Its excitation function is understood in terms of Rutherford trajectories together with the quantal process of neutron tunnelling over large distances. In addition, the exchange of up to 15 nucleons is observed down to 0.90 V c . The excitation functions for the multi-nucleon transfer products have much steeper slopes than that for one-neutron transfer, and are steeper for238U +197Au than for238U +238U, suggesting that nuclear contact is established in the associated collisions. The angular distribution for one selected multi-nucleon transfer product,227Th, shows that its formation occurs in more central collisions within contact times shorter than about 10−21 s. There is no evidence for very longlived di-nuclear systems in the these reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294679
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Reactions of40Ar with233U,235U, and238U at the barrier (1990)
    Springer
    The European physical journal 335 (1990), S. 421-430 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.CD ; 25.70.JJ ; 25.70.LM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Production cross sections for target-like transfer products in reactions of40Ar with233,235,238U at the barrier were determined using radiochemical techniques. The heaviest products detected are isotopes of californium (Z=98). In addition to the quasi-elastic component of the isotopic distributions observed in the vicinity of uranium, there are also relaxed contributions throughout the entire region. The peak positions of the isotope distributions of this component for fixed atomic number, after the transfer of 〉 3 charges, approach closely the minimum of the potential energy surfaces (PES). The experimental results thus indicate the cold formation of the reaction products. A search for long-lived heavy actinides produced, by fusion-evaporation, via isotopes of element 110 and their subsequent decay through α-decay chains, remained unsuccessful at a cross section limit of 21 pb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290190
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The influence of columnar defects on the critical current density in (Bi, Pb)2Sr2Ca2Cu3O10 + δAg tapes (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 783-786 
    Details
    ISSN: 1572-9605
    Keywords: Columnar defects ; critical current density ; tapes ; 2223 BPSCCO ; pinning energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract An excellent tool to enhance the critical current density in superconductors is the controlled introduction of defects by irradiation damage. Irradiation with 2.65 GeV Au ions provides the generation of amorphous line defects. Polycrystalline (Bi, Pb)2Sr2Ca2Cu3O10 + δ Ag tapes processed by the powder-in-tube technique were irradiated up to doses of 3.5× 1011 Au ions/cm2 at a temperature of 100 K. On the one hand, our irradiation experiments were performed to investigate the degree ofj c enhancement and, on the other hand, to examine the flux pinning mechanism in (Bi, Pb)2Sr2Ca2Cu3O10 + δ tapes. Characterization of the samples was performed by magnetization measurements using a vibrating sample magnetometer (VSM) up to 13 T in a temperature range between 5 and 100 K. Further, we have measured the relaxation of the magnetic moment before and after irradiation to determine the influence of columnar defects on the activation energyU. A comparison of the irradiation-induced effects with previous results obtained on Bi2Sr2CaCu2O8 + δ irradiation experiments is included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01320869
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    Paper (German National Licenses)
    Fulltext
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