663 research outputs found
Systematic study of proton radioactivity of spherical proton emitters within various versions of proximity potential formalisms
In this work we present a systematic study of the proton radioactivity
half-lives of spherical proton emitters within the Coulomb and proximity
potential model. We investigate 28 different versions of the proximity
potential formalisms developed for the description of proton radioactivity,
decay and heavy particle radioactivity. It is found that 21
of them are not suitable to deal with the proton radioactivity, because the
classical turning points cannot be obtained due to the fact
that the depth of the total interaction potential between the emitted proton
and the daughter nucleus is above the proton radioactivity energy. Among the
other 7 versions of the proximity potential formalisms, it is Guo2013 which
gives the lowest rms deviation in the description of the experimental
half-lives of the known spherical proton emitters. We use this proximity
potential formalism to predict the proton radioactivity half-lives of 13
spherical proton emitters, whose proton radioactivity is energetically allowed
or observed but not yet quantified, within a factor of 3.71.Comment: 10 pages, 5 figures. This paper has been accepted by The European
Physical Journal A (in press 2019
Emission Inventory for PFOS in China: Review of Past Methodologies and Suggestions
Perfluorooctane sulfonate (PFOS) is a persistent, bioaccumulative, and toxic chemical that has the potential for long-range transport in the environment. Its use in a wide variety of consumer products and industrial processes makes a detailed characterization of its emissions sources very challenging. These varied emissions sources all contribute to PFOS' existence within nearly all environmental media. Currently, China is the only country documented to still be producing PFOS, though there is no China PFOS emission inventory available. This study reviews the inventory methodologies for PFOS in other countries to suggest a China-specific methodology framework for a PFOS emission inventory. The suggested framework combines unknowns for PFOS-containing product penetration into the Chinese market with product lifecycle assumptions, centralizing these diverse sources into municipal sewage treatment plants. Releases from industrial sources can be quantified separately using another set of emission factors. Industrial sources likely to be relevant to the Chinese environment are identified
Systematic study of decay of nuclei around , shell closure within the cluster-formation model and proximity potential 1977 formalism
In the present work, we systematically study the decay
preformation factors within the cluster-formation model and
decay half-lives by the proximity potential 1977 formalism
for nuclei around , closed shells. The calculations show that the
realistic is linearly dependent on the product of valance protons
(holes) and valance neutrons (holes) . It is consistent with our
previous works [X.-D. Sun \textit{et al.},
\href{https://journals.aps.org/prc/abstract/10.1103/PhysRevC.94.024338}{ Phys.
Rev. C 94, 024338 (2016)}, J.-G. Deng \textit{et al.},
\href{https://journals.aps.org/prc/abstract/10.1103/PhysRevC.96.024318}{Phys.
Rev. C 96, 024318 (2017)}], which are model-dependent and
extracted from the ratios of calculated half-lives to
experimental data. Combining with our previous works, we confirm that the
valance proton-neutron interaction plays a key role in the
preformation for nuclei around , shell closures whether the
is model-dependent or microcosmic. In addition, our calculated
decay half-lives by using the proximity potential 1977
formalism taking evaluated by the cluster-formation model can well
reproduce the experimental data and significantly reduce the errors.Comment: 4 figures, 7 tables; Accepted by Physical Review
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