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

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

Workshop on nuclear dynamics III

Separate entries were made in the data base for the 49 papers presented. (WHK