Zeitschrift für Physik A Atoms and Nuclei

, Volume 322, Issue 4, pp 557–566

The new isotopes258105,257105,254Lr and253Lr

  • F. P. Heßberger
  • G. Münzenberg
  • S. Hofmann
  • Y. K. Agarwal
  • K. Poppensieker
  • W. Reisdorf
  • K. -H. Schmidt
  • J. R. H. Schneider
  • W. F. W. Schneider
  • H. J. Schött
  • P. Armbruster
  • B. Thuma
  • C. -C. Sahm
  • D. Vermeulen
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

Authors and Affiliations

  • F. P. Heßberger
    • 1
  • G. Münzenberg
    • 1
  • S. Hofmann
    • 1
  • Y. K. Agarwal
    • 1
    • 4
  • K. Poppensieker
    • 1
  • W. Reisdorf
    • 1
  • K. -H. Schmidt
    • 1
  • J. R. H. Schneider
    • 1
    • 5
  • W. F. W. Schneider
    • 1
  • H. J. Schött
    • 1
  • P. Armbruster
    • 1
  • B. Thuma
    • 2
  • C. -C. Sahm
    • 3
  • D. Vermeulen
    • 3
  1. 1.Gesellschaft für Schwerionenforschung mbHDarmstadtGermany
  2. 2.II. Physikalisches InstitutUniversität GießenGermany
  3. 3.Institut für KernphysikTechnische Hochschule DarmstadtGermany
  4. 4.Tata InstituteBombayIndia
  5. 5.Porsche AGWeissachGermany
  6. 6.Kraftwerk UnionOffenbachGermany
  7. 7.Nuclear Physics LaboratoryUniversity of WashingtonSeattleUSA
  8. 8.Schweizer Institut für NuklearforschungZürichSwitzerland