Mass Asymmetry Coordinate Research Articles

From a Dinuclear System to Close Binary Cosmic Objects

Applying the ideas from microscopic objects to macroscopic stellar and galactic systems, the evolution of compact di-stars and di-galaxies is studied in the mass asymmetry coordinate. The formation of stable binary systems is analyzed. The role of symmetrization of an initially asymmetric binary system is revealed in the transformation of gravitational energy into internal energy of stars or galaxies accompanied by the release of a huge amount of energy. For the contact binary stars, the change of the orbital period is explained by evolution to symmetry in mass asymmetry coordinates. The matter transfer in binary black holes is studied. The conditions for the merger of black holes in a binary system are analyzed regarding the radiation of gravitational waves. Using the model based on the Regge-like laws, the Darwin instability effect in binary systems is discussed. New analytical formulas are derived for the period of orbital rotation and the relative distance between the components of a binary system. The impossibility of the appearance of a binary cosmic object from a single cosmic object is revealed.

αdecay of Po and Rn isotopes using different choices of impinging frequency

A comprehensive study of $\ensuremath{\alpha}$ particle emergence from $^{188\text{--}218}\mathrm{Po}$ isotopes is carried out within the framework of the preformed cluster model (PCM). The mass asymmetry coordinate and the interfragment separation play crucial roles in the identification of the most probable decay channel and the barrier penetration of decay fragments. First, the barrier characteristics are studied using two choices of radii [with surface diffuseness (${C}_{i}$) and without surface diffuseness (${R}_{i}$)]. The fragmentation behavior of $^{188}\mathrm{Po}$, $^{202}\mathrm{Po}$, and $^{218}\mathrm{Po}$ isotopes is explored for the identification of the most probable decay channel in view of the structure of the fragmentation potential. The $\ensuremath{\alpha}$ decay is found to be the most prominent decay mode in the chosen set of isotopes. The preformation and penetrative probability of the decay fragments is studied with respect to increase in the neutron number of the parent nucleus. The $\ensuremath{\alpha}$ decay half-lives of polonium isotopes are calculated using classical assault frequency (${\ensuremath{\nu}}_{c}$) and quantum mechanical assault frequency (${\ensuremath{\nu}}_{q}$) and a comparison is made with the experimental data. Here, the term assault frequency is basically the impinging frequency of an $\ensuremath{\alpha}$ particle near the surface of the parent nucleus. Further, the $\ensuremath{\alpha}$ decay half-lives of the $^{198\text{--}220}\mathrm{Rn}$ isotopes are calculated using the effective assault frequency (${\ensuremath{\nu}}_{e}$) parameter, and a comparison is made with the available experimental data.

On the possibility of formation of binary cosmic systems from the single cosmic objects

In this paper, the fission of the single stars and galaxies in the mass-asymmetry (mass transfer) coordinate is considered. Using the potential energy derived as a function of mass asymmetry, the possibility of the formation of binary stars (binary galaxies) from the single stars (single galaxies) is studied.

Ternary fission analysis of Fm242,258 nuclei using equatorial and collinear cluster tripartition configurations

The quantum mechanical fragmentation theory--based three cluster model is employed to investigate the ground-state ternary fission of two Fm isotopes nuclei having atomic mass ${A}_{P}=242$ and 258. The mass asymmetry coordinate and the relative separation among the decaying fragments play a crucial role for the estimation of the fragmentation structure and related barrier penetration process. First, the choice of third fragment (${A}_{3}$) is fixed by minimizing the probable ${A}_{3}$ fragments having different proton neutron configurations. Further, the fission fragment combinations (${A}_{1}+{A}_{2}+{A}_{3}$) are identified for the fixed third fragments by selecting the channel of lower ternary fragmentation potential and higher relative fission yield. Two type of tripartition of radioactive nuclei are considered such as equatorial cluster tripartition (ECT) and collinear cluster tripartition (CCT). A comparative analysis of ternary fragmentation potential and relative fission yield within ECT and CCT geometrical arrangement is carried out for different choices of third fragment, i.e., ${A}_{3}=1$ to ${A}_{P}$/3. The choice of most probable fragments suggest that the proton and neutron magic shell closures play essential role in the ternary mass division. Finally, a relative analysis of binary and ternary fragmentation is worked out for better insight of dynamics involved.

Spontaneous fission hindrance in even-odd nuclei within a cluster approach

For even-odd isotopes of actinides and superheavy nuclei, spontaneous fission and $\ensuremath{\alpha}$-decay half-lives are calculated within the dinuclear system model and compared with the existing experimental data. All these processes are considered as the evolution of a nucleus in the charge (mass) asymmetry coordinate and in the relative distance between the centers of clusters formed. The important role of the spin dependence of total potential energy in the charge asymmetry coordinate is shown and the origin of the fission hindrance in even-odd nuclei is explained.

Cluster approach to spontaneous fission of even-even isotopes of U, Pu, Cm, Cf, Fm, No, Rf, Sg, and Hs

For even isotopes of nuclei U, Pu, Cm, Cf, Fm, No, Rf, Sg, and Hs, spontaneous fission and $\ensuremath{\alpha}$-decay half-lives are calculated within the dinuclear system model and compared with existing experimental data. Cluster radioactivity half-lives are also described for even U, Pu, and Cm isotopes. All these processes are considered for the evolution of a nucleus in the charge (mass) asymmetry coordinate and in the relative distance between the centers of clusters formed. The important roles of the driving potential and mass parameter in the charge asymmetry coordinate are shown for spontaneous fission. The global isotopic trends of spontaneous fission and $\ensuremath{\alpha}$-decay half-lives are studied. Drastic changes in the functional dependence of spontaneous fission half-life on the neutron number and in the absolute values of half-lives in the U--No and Rf--Hs nuclear groups are explained.

From Dinuclear Systems to Close Binary Stars and Galaxies

The evolution of close binary cosmic objects in the mass-asymmetry coordinate is considered. Conditions for the formation of stable symmetric binary stars and galaxies are analyzed. The role of symmetrization of an asymmetric binary system in the transformation of the potential energy into the internal energy and in the release of a large amount of energy is explained.

Origin of the orbital period change in contact binary stars

The evolution of contact binary star systems in mass asymmetry (transfer) coordinate is considered. The orbital period changes are explained by an evolution in mass asymmetry towards the symmetry (symmetrization of binary system). It is predicted that decreasing and increasing orbital periods are related, respectively, with the nonoverlapping and overlapping stage of the binary star during its symmetrization. A huge amount of energy [Formula: see text][Formula: see text]J is converted from the potential energy into internal energy of the stars during the symmetrization. As shown, the merger of stars in the binary systems, including KIC 9832227, is energetically an unfavorable process. The sensitivity of the calculated results to the values of total mass and orbital angular momentum is analyzed.

Close Binary Galaxies: Application to Source of Energy and Expansion in Universe

Applying the microscopic nuclear physics ideas for fusion reactions to macroscopic galactic systems, we study the evolution of the compact binary galaxy in mass asymmetry (transfer) coordinate. The conditions for the formation of stable symmetric binary galaxy are analyzed. The role of symmetrization of asymmetric binary galaxy in the transformation of gravitational energy into internal energy of galaxies accompanied by the release of a large amount of energy during the symmetrization process is revealed.

From Dinuclear Systems to Close Binary Stars: Application to Mass Transfer

Applying the microscopic nuclear physics ideas to macroscopic stellar systems, we study the evolution of the compact di-stars in mass asymmetry (transfer) coordinate. Depending on the internal stru...

From dinuclear systems to close binary stars: Application to source of energy in the universe

The evolution of close binary stars in mass asymmetry (transfer) coordinate is considered. The conditions for the formation of stable symmetric binary stars are analyzed. The role of symmetrization of asymmetric binary star in the transformation of potential energy into internal energy of star and the release of a large amount of energy is revealed.

From dinuclear systems to close binary stars: Application to mass transfer

Applying the microscopic nuclear physics ideas to macroscopic stellar systems, we study the evolution of the compact di-stars in mass asymmetry (transfer) coordinate. Depending on the internal structure of constituent stars, the initial mass asymmetry, total mass, and orbital angular momentum, the close di-star system can either exist in symmetric configuration or fuse into mono-star. The limitations for the formation of stable symmetric binary stars are analyzed.

Preformation probability of two-proton emitters

Within the cluster-core model picture using the preformed cluster model, proton rich, 2-proton emitting nuclei are studied. The experimentally established [Formula: see text]Fe, [Formula: see text]Ni, [Formula: see text]Zn and [Formula: see text]Kr are investigated in terms of simple potential energy surfaces for all possible cluster plus core configurations of the 2-proton emitting nuclei. The calculated potential energy surfaces reveal a strong minimum for 2-proton-cluster plus core configuration. In addition, the calculations are carried out for the theoretically studied 2-proton emitters such as [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], which also reveal 2-proton cluster plus core configuration as the favorable one possessing strong minimum in the potential energy surface. Furthermore, the calculated potential energies are used to calculate the preformation probability by solving the stationary Schrödinger equation of motion in mass asymmetry coordinate. The formation yield also clearly reveals a larger formation probability for the 2-proton cluster plus core configuration for all the nuclei studied. The Q-value systematic of 1-proton, 2-proton, 4-proton and 4He is also analyzed.

Four-dimensional Langevin dynamics of heavy-ion-induced fission

A four-dimensional dynamical model based on Langevin equations was developed and applied to calculate a wide set of experimental observables for the reactions ${}^{16}\mathrm{O}+{}^{208}\mathrm{Pb}\ensuremath{\rightarrow}{}^{224}\mathrm{Th}$ and ${}^{16}\mathrm{O}+{}^{232}\mathrm{Th}\ensuremath{\rightarrow}{}^{248}\mathrm{Cf}$ over a wide range of excitation energy. The fusion-fission and evaporation residue cross sections, fission fragment mass-energy distribution parameters, prescission neutron multiplicities, and anisotropy of angular distribution of fission fragments could be reasonably reproduced using a modified one-body mechanism for nuclear friction with a reduction coefficient of the contribution from a wall formula ${k}_{s}\ensuremath{\simeq}0.25$ and a dissipation coefficient for the orientation degree of freedom ($K$ coordinate) ${\ensuremath{\gamma}}_{K}\ensuremath{\simeq}$ 0.077 ${(\mathrm{MeV}\phantom{\rule{0.16em}{0ex}}\mathrm{zs})}^{\ensuremath{-}1/2}$. Inclusion of the $K$ coordinate into calculation of potential energy changes the stiffness of the nucleus with respect to mass asymmetry coordinate for the values of $K\ensuremath{\ne}0$ and results in a shift of the Businaro-Gallone point towards larger ${Z}^{2}/A$ values. The experimental data on the fission fragment mass-energy distribution parameters together with mean prescission neutron multiplicity for heavy fissioning nuclei are reproduced through the four-dimensional Langevin calculations more accurately than through three-dimensional calculations.

Multiple reflection-asymmetric-type band structures in 220Th and dinuclear model

The negative parity bands in $^{220}$Th are analyzed within the dinuclear system model which was previously used for describing the alternating-parity bands in deformed actinides. The model is based on the assumption that cluster type shapes are produced by the motion of nuclear system in the mass-asymmetry coordinate. To describe the reflection-asymmetric collective modes characterized by nonzero values of $K$, the intrinsic excitations of clusters are taken into account. The angular momentum dependence of the parity splitting and the staggering behavior of the $B(E1)/B(E2)$ ratios as functions of angular momentum are explained.

Emission of charged particles from excited compound nuclei

The formation of excited compound nucleus (CN) and its statistical decay is investigated within the dinuclear system (DNS) model.The initial DNS is formed in the entrance channel when the projectile is captured by a target, and then the evolution of DNS in mass asymmetry coordinate leads to formation of the hot CN. The emission barriers for complex fragments were calculated within the DNS model by using the double folding procedure for the interaction potential. It is shown that cross sections for complex fragment emission become larger when excited CN is more neutron deficient. This approach gives also an opportunity to calculate the new neutron deficient isotopes production cross sections and can be applied to describe the hot fission of heavy systems.The model was tested by comparison of calculated results with experimental data

Cluster approach to the structure of nuclei with Z ≥ 96

The properties of alternating parity bands in heavy nuclei 234Th, 239–242U, 241–245Pu, 243–248Cm, 245–250Cf, 248–251Fm, 249–254No, 253–256Rf, and 258Sg are analyzed within the dinuclearsystem model. The model is based on the assumption that the cluster-type shapes are produced by the motion of the nuclear system in the mass-asymmetry coordinate. The energies of the low-lying states whose parity is opposite to the parity of the ground state are predicted for the first time.

Possible alternative parity bands in the heaviest nuclei

The low-lying alternative parity bands in heaviest nuclei are predicted for the first time. The parity splitting and electric dipole, quadrupole, and octupole transition moments of heavy nuclei are calculated within a cluster model. The model is based on the assumption that reflection asymmetric shapes are produced by the motion of the nuclear system in the mass asymmetry coordinate.

Influence of angular momentum on fission fragment mass distribution: Interpretation within Langevin dynamics

Dependence of fission fragments mass distribution on the angular momentum within Langevin dynamics is studied. The calculations are performed in the framework of the rotating temperature-dependent finite-range liquid drop model. The calculations are done for the five nuclei, representing heavy fissioning nuclei, medium fissioning nuclei and light fissioning one with the angular momentum varied in the wide range from l = 0 to l = 70 ℏ . The dependence coefficients d σ M 2 / d l 2 for the investigated nuclei are extracted. The comparison of the extracted values with the experimental data reveals a good agreement for all the cases (the heavy, medium, and light fissioning nuclei). It is found out that the obtained dependence of σ M 2 on l can be explained with the help of temperature at scission as a function of l. The latter dependence is determined by dependence of the mean prescission neutron multiplicity on l. The analysis of this dependence is done as a competition between fission process and neutron evaporation. “Remembering of the former large fluctuations of mass asymmetry coordinate during descent from the saddle to scission” is considered. It is shown that the “remembering effect” takes place, but does not play a crucial role for the investigated dependence of σ M 2 on l.

Cluster interpretation of parity doublet rotational bands in odd-mass nuclei

The structure of parity doublet rotational bands in odd actinides and medium mass nuclei is described in a cluster model. The model is based on the assumption that cluster-type shapes are produced by the motion of the nuclear system in the mass-asymmetry coordinate. The calculated rotational bands and the electric dipole transitions between the members of the parity doublet are in good agreement with the experimental data.