Zeitschrift für Physik A Atoms and Nuclei

, Volume 322, Issue 4, pp 557–566

The new isotopes258105,257105,254Lr and253Lr

Authors

  • F. P. Heßberger
    • Gesellschaft für Schwerionenforschung mbH
  • G. Münzenberg
    • Gesellschaft für Schwerionenforschung mbH
  • S. Hofmann
    • Gesellschaft für Schwerionenforschung mbH
  • Y. K. Agarwal
    • Gesellschaft für Schwerionenforschung mbH
    • Tata Institute
  • K. Poppensieker
    • Gesellschaft für Schwerionenforschung mbH
  • W. Reisdorf
    • Gesellschaft für Schwerionenforschung mbH
  • K. -H. Schmidt
    • Gesellschaft für Schwerionenforschung mbH
  • J. R. H. Schneider
    • Gesellschaft für Schwerionenforschung mbH
    • Porsche AG
  • W. F. W. Schneider
    • Gesellschaft für Schwerionenforschung mbH
  • H. J. Schött
    • Gesellschaft für Schwerionenforschung mbH
  • P. Armbruster
    • Gesellschaft für Schwerionenforschung mbH
  • B. Thuma
    • II. Physikalisches InstitutUniversität Gießen
  • C. -C. Sahm
    • Institut für KernphysikTechnische Hochschule Darmstadt
  • D. Vermeulen
    • Institut für KernphysikTechnische Hochschule Darmstadt
Nuclei

DOI: 10.1007/BF01415134

Cite this article as:
Heßberger, F.P., Münzenberg, G., Hofmann, S. et al. Z Physik A (1985) 322: 557. doi:10.1007/BF01415134

Abstract

Evaporation residues from the heavy-ion fusion reaction50Ti on209Bi were investigated. They were separated from the projectile beam by the velocity filter SHIP and identified after implantation into an array of position-sensitive surface-barrier detectors by analyzing theirα-decay chains. Spontaneous fission was also observed.

Four newα emitters,258105 (T1/2=4.4−0.6+0.9s),257105 (T1/2= 1.4−0.3+0.6s),254Lr (T1/2= 13−2+3s), and253Lr (T1/2=1.3−0.3+0.6s) could be identified. For the isotope257105 we obtained a spontaneous-fission branch of about 20%. A spontaneous-fission activity with a halflife comparable to that for theα decay of258105 was explained as fission of258104, formed by electron capture from258105.

An excitation function for evaporation-residue production was measured for bombarding energies in the range ofECM=184.4 MeV toECM=196.6 MeV. Nearly all evaporation residues we observed, could be attributed to the 1n and 2n deexcitation channels. The maximum cross sections wereσ(1n)=c/2.9±0.3) nbarn, andσ(2n)=c/2.1±0.8) nbarn, respectively.

We could measure the total kinetic energy of the fission fragments of258104 to be TKE=(220±15) MeV, a value that fits into empirical systematics based on aZ2/A1/3 dependence.

PACS

23.60.+e25.85. Ca25.70. Jj27.90.+b

Copyright information

© Springer-Verlag 1985