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Title: Experiments on Nuclear Structure and Synthesis of Superheavy Elements at SHIP

Abstract

Experiments to synthesize isotopes of heaviest elements and to investigate as well their production mechanisms as their nuclear properties have been performed during the past three decades at the velocty filter SHIP. Isotopes of six so far unknown elements with atomic numbers Z = 107-112 have been identified, excitation functions for production of transactinide isotopes in so-called 'cold' fusion reactions, using Pb- or Bi- targets and 'medium' heavy projectiles from 50Ti to 64Ni have been measured. In recent years experiments also concentrated on nuclear structure investigations by means of evaporation residue (ER)-{gamma}- or {alpha}-{gamma}-decay spectroscopy resulting in systematic studies of low lying Nilsson levels in odd mass nuclei and identification of high lying (E* > 1 MeV) isomeric states in neutron deficient nobelium isotopes.

Authors:
 [1]
  1. Gesellschaft fuer Schwerionenforschung mbH, Planckstrasse 1, D-64291 Darmstadt (Germany)
Publication Date:
OSTI Identifier:
21056728
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 891; Journal Issue: 1; Conference: 6. Symposium on nuclear physics, Tours (France), 5-8 Sep 2006; Other Information: DOI: 10.1063/1.2713495; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALPHA DECAY; ALPHA SPECTROSCOPY; BISMUTH 209 TARGET; COLD FUSION; ENERGY-LEVEL TRANSITIONS; EVAPORATION MODEL; EXCITATION FUNCTIONS; GAMMA DECAY; GAMMA SPECTROSCOPY; HEAVY ION FUSION REACTIONS; ISOMERIC NUCLEI; LEAD 208 TARGET; MEV RANGE; NEUTRONS; NICKEL 60 REACTIONS; NOBELIUM ISOTOPES; NUCLEAR STRUCTURE; TITANIUM 50 REACTIONS; TRANSACTINIDE ELEMENTS

Citation Formats

Hessberger, F. P.. Experiments on Nuclear Structure and Synthesis of Superheavy Elements at SHIP. United States: N. p., 2007. Web. doi:10.1063/1.2713495.
Hessberger, F. P.. Experiments on Nuclear Structure and Synthesis of Superheavy Elements at SHIP. United States. doi:10.1063/1.2713495.
Hessberger, F. P.. Mon . "Experiments on Nuclear Structure and Synthesis of Superheavy Elements at SHIP". United States. doi:10.1063/1.2713495.
@article{osti_21056728,
title = {Experiments on Nuclear Structure and Synthesis of Superheavy Elements at SHIP},
author = {Hessberger, F. P.},
abstractNote = {Experiments to synthesize isotopes of heaviest elements and to investigate as well their production mechanisms as their nuclear properties have been performed during the past three decades at the velocty filter SHIP. Isotopes of six so far unknown elements with atomic numbers Z = 107-112 have been identified, excitation functions for production of transactinide isotopes in so-called 'cold' fusion reactions, using Pb- or Bi- targets and 'medium' heavy projectiles from 50Ti to 64Ni have been measured. In recent years experiments also concentrated on nuclear structure investigations by means of evaporation residue (ER)-{gamma}- or {alpha}-{gamma}-decay spectroscopy resulting in systematic studies of low lying Nilsson levels in odd mass nuclei and identification of high lying (E* > 1 MeV) isomeric states in neutron deficient nobelium isotopes.},
doi = {10.1063/1.2713495},
journal = {AIP Conference Proceedings},
number = 1,
volume = 891,
place = {United States},
year = {Mon Feb 26 00:00:00 EST 2007},
month = {Mon Feb 26 00:00:00 EST 2007}
}
  • Experiments have been carried out on the synthesis of the neutron-deficient isotopes of superheavy elements in complete-fusion reactions in beams of /sup 48/Ca ions. For the reactions /sup 233/U(/sup 48/Ca,2n) and /sup 231/Pa(/sup 48/Ca,3n) we attempted to observe /sup 255/Fm and /sup 256/Md-the final product of the ..cap alpha..-decay chains of the parent nuclei /sup 279/112 and /sup 276/111. For the reactions /sup 231/Pa(/sup 48/Ca,xn) and /sup 232/Th(/sup 48/Ca,xn) we attempted to detect spontaneously fissile products with half-life > or =3 msec. The limits obtained for the cross sections are discussed from the point of view of the production mechanismmore » and properties of superheavy nuclei with Z=110--112 and N=165--168.« less
  • Evaporation residue production was investigated at SHIP in cold fusion reactions of Pb- and Bi-target nuclei with projectiles of elements between Ti (Z=22) and Se (Z=34) leading to compound nuclei Z{sub CN}=104-116. The isotopes {sup 269}110, {sup 271}110, {sup 272}111, and {sup 277}112 of the elements Z=110, Z=111 and Z=112 were unambiguously identified for the first time in bombardments of {sup 208}Pb, {sup 209}Bi with {sup 62,64}Ni and {sup 70}Zn. Excitation functions for {sup 50}Ti+{sup 208}Pb and {sup 58}Fe+{sup 208}Pb were measured with high precision, three new spontaneous fission (sf) activities {sup 253}104, {sup 254}104, {sup 258}106 were identified. Amore » small {alpha}-decay branch of the even-even nucleus {sup 256}104 (b{sub {alpha}}{approx_equal}0.003) was confirmed, allowing to estimate mass excesses {delta}mc{sup 2} for N-Z=48 nuclei up to {sup 264}Hs (Z=108). An analysis of the {alpha}-decay chains observed in a bombardment of {sup 209}Bi with {sup 58}Fe projectiles showed evidence for an isomeric state in {sup 266}Mt (Z=109). We further report on an attempt to produce element 116 and a second isotope of element 112 by the reactions {sup 82}Se+{sup 208}Pb and {sup 68}Zn+{sup 208}Pb, respectively.« less
  • The exciting results search for superheavy elements which have been achieved in the recent years have triggered a broad range of activities. Apart from experiments to attempt the synthesis of new elements, nuclear structure investigations in the transactinide region has become possibly for Z up to 108 or 110. Heavy element chemistry has successfully placed Hs in the periodic table and is no attacking element 112. The development of accelerators and experimental methods promises advances to enable the extension of these investigations in regions closer to the ''island of stability''. Mass measurements using ion traps and neutron rich unstable beammore » species for the systematic investigation of nuclear structure and reaction mechanisms for heavy neutron rich system are believed to complete the variety of tools in future.« less