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81.
The \begin{document}$ \alpha $\end{document} ![]()
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-particle preformation factors of nuclei above doubly magic nuclei \begin{document}$ ^{100} $\end{document} ![]()
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Sn and \begin{document}$ ^{208} $\end{document} ![]()
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Pb are investigated within the generalized liquid drop model. The results show that the \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation factors of nuclei near self-conjugate doubly magic \begin{document}$ ^{100} $\end{document} ![]()
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Sn are significantly larger than those of analogous nuclei just above \begin{document}$ ^{208} $\end{document} ![]()
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Pb, and they will be enhanced as the nuclei move towards the \begin{document}$ N = Z $\end{document} ![]()
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line. The proton–neutron correlation energy \begin{document}$ E_{p-n} $\end{document} ![]()
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and two protons–two neutrons correlation energy \begin{document}$ E_{2p-2n} $\end{document} ![]()
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of nuclei near \begin{document}$ ^{100} $\end{document} ![]()
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Sn also exhibit a similar situation, indicating that the interactions between protons and neutrons occupying similar single-particle orbitals could enhance the \begin{document}$ \alpha $\end{document} ![]()
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-particle preformation factors and result in superallowed \begin{document}$ \alpha $\end{document} ![]()
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decay. This also provides evidence of the significant role of the proton–neutron interaction on \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation. Also, the linear relationship between \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation factors and the product of valence protons and valence neutrons for nuclei around \begin{document}$ ^{208} $\end{document} ![]()
![]()
Pb is broken in the \begin{document}$ ^{100} $\end{document} ![]()
![]()
Sn region because the \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation factor is enhanced when a nucleus near \begin{document}$ ^{100} $\end{document} ![]()
![]()
Sn moves towards the \begin{document}$ N = Z $\end{document} ![]()
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line. Furthermore, the calculated \begin{document}$ \alpha $\end{document} ![]()
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decay half-lives fit well with the experimental data, including the recent observed self-conjugate nuclei \begin{document}$ ^{104} $\end{document} ![]()
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Te and \begin{document}$ ^{108} $\end{document} ![]()
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Xe [Phys. Rev. Lett. 121, 182501 (2018)]. 相似文献
82.
Mitiyasu Miyasita Katsuhiko Higuchi Masahiko Higuchi 《Physica B: Condensed Matter》2012,407(14):2758-2762
We present an alternative scheme for calculating the unrestricted Hartree–Fock (HF) equation. The scheme is based on the variational method utilizing the sophisticated basis functions that include no adjustable parameters. The validity of the present scheme is confirmed by actual calculations of the boron and neon atoms. The total energy of the present scheme is lower than that of the conventional restrictive HF equation, but higher than that of the CI method. Also, the resultant wave function satisfies the electron–nucleus cusp condition. 相似文献
83.
The thermal variant of the classical nucleation‐growth‐separation principle is shown, both theoretically and experimentally, to be a reliable tool for studying protein crystal nucleation. The classical nucleation theory is used to elucidate the temperature dependence of crystal nucleus size. A one‐to‐one ratio of the number density of nuclei formed to crystals grown to visible size is achieved using the nucleation‐growth‐separation method. The experiments conducted in such a way show that new nuclei are prevented from appearing while avoiding any crystal loss due to dissolution. The same method is used to study experimentally the interval of growth temperatures where the number density of (nucleated) crystals is relatively insensitive to the growth temperature. It is argued that this temperature interval corresponds to the width of the so‐called metastable zone. 相似文献
84.
Baranac-Stojanović M Koch A Kleinpeter E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(1):370-376
Based on the nucleus‐independent chemical shift (NICS) concept, isotropic magnetic shielding values have been computed along the three Cartesian axes for ethene, cyclobutadiene, benzene, naphthalene, and benzocyclobutadiene, starting from the molecular/ring center up to 10 Å away. These through‐space NMR spectroscopic shielding (TSNMRS) values, which reflect the anisotropic effects, have been broken down into contributions from localized‐ and canonical molecular orbitals (LMOs and CMOs); these contributions revealed that the proton NMR spectroscopic chemical shifts of nuclei that are spatially close to the C?C double bond or the aromatic ring should not be explained in terms of the conventionally accepted π‐electron shielding/deshielding effects. In fact, these effects followed the predictions only for the antiaromatic cyclobutadiene ring. 相似文献
85.
86.
F. M. Fernández N. Aquino A. Flores‐Riveros 《International journal of quantum chemistry》2012,112(3):823-828
We calculate the ground‐state energy and other physical properties of the hydrogen atom inside a spherical box with an impenetrable wall. We apply the variational method and show that the total, kinetic, and potential energies for the moving nucleus model are greater than those for the case in which the nucleus is clamped at the box center. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
87.
Z. Sosin R. Płaneta T. Ciszek J. Brzychczyk W. Gawlikowicz K. Grotowski S. Micek P. Pawłowski A. Wieloch A.J. Cole D. Benchekroun E. Bisquer A. Chabane M. Charvet B. Cheynis A. Demeyer P. Désesquelles E. Gerlic A. Giorni D. Guinet D. Heuer P. Lautesse L. Lebreton A. Lléres M. Stern L. Vagneron J.B. Viano 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):305-310
The shape of the velocity distributions of charged particles projected on the beam direction can be explained if emissions
from the hot projectile-like fragment and the target-like fragment are supplemented by an emission from an intermediate velocity
source located between them. The creation of this source is predicted by a two-stage reaction model where, in the second stage,
some of the nucleons identified in the first stage as participants form a group of clusters located in the region between
the colliding nuclei. The cluster coalescence process is governed on the average by the maximum value of entropy, although
its fluctuations are also significant. The properties of the intermediate velocity source are precisely described, including
the isotopic composition of the emitted particles.
Received: 12 March 2001 / Accepted: 20 June 2001 相似文献
88.
S. Mukherjee A. Sharma S. Sodaye B.S. Tomar A. Goswami S.B. Manohar 《The European Physical Journal A - Hadrons and Nuclei》2001,12(2):199-205
Incomplete fusion reactions were investigated by measuring the excitation functions of nine evaporation residues in 16O + 51V reaction in the beam energy 4-6 MeV/amu, using the well-known recoil catcher technique and gamma-ray spectrometry. The experimental
data were compared with that obtained from Monte Carlo simulation calculations using the PACE2 code. The results indicate
the presence of incomplete fusion process in the production of two alpha emission products. This was further confirmed by
the measurement of recoil range distribution of these isotopes at 96 MeV beam energy. Calculations of the average angular
momentum associated with these products revealed the peripheral nature of these ICF reactions.
Received: 20 June 2001 / Accepted: 11 September 2001 相似文献
89.
超重核的基态性质 总被引:1,自引:0,他引:1
用Skyrme Hartree Fock+BCS方法计算了超重核的基态性质,讨论了结合能、α衰变、形变、壳结构和自发裂变等问题.计算得到的结合能较好地反映了实验测量值,α衰变能与实验值符合很好.发现基本上有两种类型的超重核形变:在270108核附近的β2≈0.2的长椭球形变和在298114核附近的近球形形变.单粒子能级分布计算表明:在质子Z=108和中子N=162存在变形壳,在质子Z=114和中子N=184存在球形壳.用得到的α衰变能和Viola Seaborg公式估算了α衰变半寿命,能合理地符合实验测量值. The ground state properties of superheavy nuclei are investigated using the Skyrme Hartree Fock model. The pairing correlation is treated by the BCS method with the pairing δ force. Binding energies, α decays, spontaneous fissions, shell structures and deformations are discussed. Our calculations reproduce experimential binding energies and α decay energies.It is found that superheavy nuclei can be grouped with two kinds of deformations: i) well deformed prolate shapes (β2≈0.2) around 270108... 相似文献
90.
本文定义了locale的内部算子与边界算子,详细讨论了这两个算子的性质,进一步得到了locale形式的Kuratowski定理。 相似文献