194 research outputs found
Superheavy nuclei from 48Ca-induced reactions
AbstractThe discovery and investigation of the new region of superheavy nuclei at the DGFRS separator based on fusion reactions of 48Ca with 238U–249Cf target nuclei are reviewed. The production cross sections and summaries of the decay properties, including the results of the posterior experiments performed at the SHIP, BGS, and TASCA separators, as well as at the chemistry setups, are discussed and compared with the theoretical calculations and the systematic trends in the α-decay and spontaneous fission properties. The properties of the new nuclei, isotopes of elements 112–118, and their decay products demonstrate significant increases in the stability of the heaviest nuclei with increasing neutron number and closer approach to magic number N=184
Semiempirical Shell Model Masses with Magic Number Z = 126 for Superheavy Elements
A semiempirical shell model mass equation applicable to superheavy elements
up to Z = 126 is presented and shown to have a high predictive power. The
equation is applied to the recently discovered superheavy nuclei Z = 118, A =
293 and Z = 114, A = 289 and their decay products.Comment: 7 pages, including 2 figures and 2 table
Neutron Transfer Dynamics and Doorway to Fusion in Time-Dependent Hartree-Fock Theory
We analyze the details of mass exchange in the vicinity of the Coulomb
barrier for heavy-ion collisions involving neutron-rich nuclei using the
time-dependent Hartree-Fock (TDHF) theory. We discuss the time-dependence of
transfer and show that the potential barriers seen by individual
single-particle states can be considerably different than the effective barrier
for the two interacting nuclei having a single center-of-mass. For this reason
we observe a substantial transfer probability even at energies below the
effective barrier.Comment: 6 pages, 9 figure
Shell Corrections of Superheavy Nuclei in Self-Consistent Calculations
Shell corrections to the nuclear binding energy as a measure of shell effects
in superheavy nuclei are studied within the self-consistent Skyrme-Hartree-Fock
and Relativistic Mean-Field theories. Due to the presence of low-lying proton
continuum resulting in a free particle gas, special attention is paid to the
treatment of single-particle level density. To cure the pathological behavior
of shell correction around the particle threshold, the method based on the
Green's function approach has been adopted. It is demonstrated that for the
vast majority of Skyrme interactions commonly employed in nuclear structure
calculations, the strongest shell stabilization appears for Z=124, and 126, and
for N=184. On the other hand, in the relativistic approaches the strongest
spherical shell effect appears systematically for Z=120 and N=172. This
difference has probably its roots in the spin-orbit potential. We have also
shown that, in contrast to shell corrections which are fairly independent on
the force, macroscopic energies extracted from self-consistent calculations
strongly depend on the actual force parametrisation used. That is, the A and Z
dependence of mass surface when extrapolating to unknown superheavy nuclei is
prone to significant theoretical uncertainties.Comment: 14 pages REVTeX, 8 eps figures, submitted to Phys. Rev.
GABRIELA : a new detector array for gamma-ray and conversion electron spectroscopy of transfermium elements
With the aid of the Geant4 Monte Carlo simulation package a new detection
system has been designed for the focal plane of the recoil separator VASSILISSA
situated at the Flerov Laboratory of Nuclear Reactions, JINR, Dubna. GABRIELA
(Gamma Alpha Beta Recoil Investigations with the Electromagnetic Analyser
VASSILISSA) has been optimised to detect the arrival of reaction products and
their subsequent radioactive decays involving the emission of alpha- and
beta-particles, fission fragments, gamma- and X-rays, and conversion electrons.
The new detector system is described and the results of the first commissioning
experiments are presented.Comment: 24 pages, Submitted to NIM
5He ternary fission yields of 252Cf and 235U(n,f)
The relative 4He and 5He ternary fission yields were determined from a careful analysis of the energy distribution of α spectra from a new measurement with a 252Cf source and from published data on 252Cf and 235U(n,f). The kinetic energies of the 5He and 4He ternary particles were found to be approximately 11 and 16 MeV, respectively. 5He particles contribute 10-20% to the total alpha yield with the remainder originating from 4He accompanied fission
Spin distribution measurement for 64Ni + 100Mo at near and above barrier energies
Spin distribution measurements were performed for the reaction 64Ni + 100Mo at three beam energies ranging from 230 to 260 MeV. Compound nucleus (CN) spin distributions were obtained channel selective for each evaporation residue populated by the de-excitation cascade. A comparison of the spin distribution at different beam energies indicates that its slope becomes steeper and steeper with increasing beam energy. This change in slope of the spin distribution is mainly due to the onset of fission competition with particle evaporation at higher beam energies
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