50 research outputs found
Search for Fission-Like Processes in the 200 MeV p+ 28-Si Reaction
This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit
Total Mass and Charge Distributions in the p + 27-Al Reaction at 180 MeV
This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit
A Global Study of the p+27-Al Reaction at 180 MeV
This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit
On the alpha activity of natural tungsten isotopes
The indication for the alpha decay of 180-W with a half-life
T1/2=1.1+0.8-0.4(stat)+-0.3(syst)x10^18 yr has been observed for the first time
with the help of the super-low background 116-CdWO_4 crystal scintillators. In
conservative approach the lower limit on half-life of 180-W has been
established as T1/2>0.7x10^18 yr at 90% C.L. Besides, new T1/2 bounds were set
for alpha decay of 182-W, 183-W, 184-W and 186-W at the level of 10^20 yr.Comment: 16 pages, 8 figures, accepted in Phys. Rev.
Sub-barrier capture with quantum diffusion approach: actinide-based reactions
With the quantum diffusion approach the behavior of capture cross sections
and mean-square angular momenta of captured systems are revealed in the
reactions with deformed nuclei at subbarrier energies. The calculated results
are in a good agreement with existing experimental data. With decreasing
bombarding energy under the barrier the external turning point of the
nucleusnucleus potential leaves the region of short-range nuclear interaction
and action of friction. Because of this change of the regime of interaction, an
unexpected enhancement of the capture cross section is expected at bombarding
energies far below the Coulomb barrier. This effect is shown its worth in the
dependence of mean-square angular momentum of captured system on the bombarding
energy. From the comparison of calculated and experimental capture cross
sections, the importance of quasifission near the entrance channel is shown for
the actinide-based reactions leading to superheavy nuclei.Comment: 11 pages, 16 figures, Regular Articl
The analysis of predictability of alpha-decay half-life formulae and the alpha partial half-lives of some exotic nuclei
The predictabilities of the three alpha-decay half-life formulae, the Royer
GLDM, the Viola-Seaborg and the Sobiczewski-Parkhomenko formulae, have been
evaluated by developing a method based on the ansatz of standard experimental
benchmarking. The coefficients of each formula were re-derived using the
reliable data of the alpha-standards nuclei. The modified formulae that
resulted were used to evaluate the accuracies of the formulae towards the
prediction of half-lives of a set of nuclides with well-studied alpha-
spectroscopic data as well as a set of exotic alpha-emitters. Further, a simple
linear optimization of the modified formulae allowed adjustments for the
insufficient statistics of the primary data set without changing the modified
formulae. While the three modified formulae showed equivalent results for all
the medium heavy nuclei except the odd-odd, the modified GLDM showed relatively
the best figures of merit for the odd-odd and superheavy nuclides.Comment: 16 pages, 4 tables, 2 figure
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ON THE LIGHT ELEMENT ABUNDANCES, GALACTIC EVOLUTION, AND A MORE SENSITIVE INDICATOR OF THE UNIVERSAL BARYON DENSITY
Nuclear chemistry progress report. [Dept. of Chemistry and Cyclotron Lab. , Univ. of Maryland, College Park, August 1, 1978 to July 31, 1979]
Research activities during the period August 1, 1978 to July 31, 1979 are summarized. The major effort has continued to be devoted to the study of nucleon exchange and energy dissipation mechanisms in damped heavy-ion reactions. Among the most significant accomplishments of the program during the past year has been the measurement of damped fragment spectra with discrete Z and A resolution. These studies provided detailed information on the A/Z equilibration and nucleon exchange processes in damped heavy-ion collisions, gave evidence for structure in the partially damped energy spectra for the Fe + Fe reaction, showed the importance of target-projectile mass asymmetry in governing the evolution of damped reactions, and gave tentative evidence for several new isotopes in the Z = 22 to 26 range. Other experiments utilized the fission-fragment angular correlation technique to determine the linear momentum transfer from projectile to target for /sup 16/O reactions in the 8- to 20-MeV/u region and to study simultaneously light-ion spectra (Z = 1 to 8) in coincidence with correlated events. These studies provided a much clearer picture of properties of central and peripheral collisions in heavy-ion reactions, as well as the transition between these two extremes. In addition, problems of Li, Be, and B nucleosynthesis and the relationship of these results to the question of the expanding universe were investigated. Individual sections with significant amounts of information are abstracted separately. (RWR
Nuclear chemistry progress report. [Summary of research at the University of Maryland]
The present progress report attempts to summarize the research results obtained from the nuclear reactions aspect of the nuclear chemistry research program at the University of Maryland. The principal areas of investigation summarized in the present report deal primarily with reaction mechanism studies in heavy-ion-induced nuclear reactions and the study of nuclear reactions of astro physical significance
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Workshop on nuclear dynamics III
Separate entries were made in the data base for the 49 papers presented. (WHK