Nuclear Theory·nucl-th

Tuesday·May 23, 2023

13 papers—5 primary·8 cross-listed

01
[Submitted on 20 May 2023]
Modified approach for accounting for dissipation in theoretical description of fusion of complex nuclei
I. I. Gontchar · M. V. Chushnyakova
The process of fusion of complex nuclei is of significant interest as an example of the collective nuclear motion of large amplitude as well as a route for synthesis of new superheavy chemical elements. This process is accompanied by the dissipation of the energy of collective motion, at least at the last stage. The dissipative nature of fusion is accounted for in many theoretical approaches. In the present work, we propose a modified method for accounting for dissipation. The main idea is to use the superfluid model for evaluating nuclear temperature, not the Fermi-gas model like in previous approaches. The calculations of the fusion (capture) cross sections are performed for reaction 16O+92Zr at the collision energies ranging from 46 up to 70 MeV. For this reaction and at these conditions it turns out, that the more complicated superfluid model results in the cross sections which are indistinguishable from the ones obtained using the much simpler Fermi-gas model.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2305.12075 [pdf]
1 citation
02
[Submitted on 20 May 2023]
Charge radii of atomic nuclei and shell effects
M. V. Chushnyakova · I. I. Gontchar · E. V. Kulik
In the present work, we study the experimental data on the root mean square charge radii of the spherical atomic nuclei. The purpose of this analysis is to clarify what is the manifestation of the neutron shells in the considered observable and to find regularities in the behavior of the charge radii when a shell neutron is crossed. As the result, we have found manifestations of the shells N_sh=8,28,50 and 82. It turns out that the well-known shells with the neutron numbers 20 and 126 do not show up. The present analysis is performed by means of the relative charge radius x(N,N_sh,Z). This value is equal to the charge radius of a given isotope over the charge radius of the isotope of the given element with the closed neutron shell. It is shown that the values of x form groups corresponding to different values of N_sh. Prediction for unknown charge radius of sulfur-30 has been made.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2305.12174 [pdf]
0 citations
03
[Submitted on 21 May 2023]
Singlet cross section and the tensor interaction in $p p \to Λ ˉ Λ$
Deepak Pachattu
In this short paper, we demonstrate using irreducible tensorial techniques and in a model-independent way, why tensor interactions and also orbital-angular momentum-changing vector interactions are absent in the singlet unpolarized differential cross section for the reaction $p p \to Λ ˉ Λ$ .
Comments:
2 pages, no figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
2305.12531 [pdf]
0 citations
04
[Submitted on 22 May 2023]
On the screening condition in the core of neutron stars
Dmitry Kobyakov
Earlier, the screening condition in neutron star core has been formulated as equality of velocities of superconducting protons and the electrons $v_{p} = u_{e}$ at wavenumbers $q ≪ λ^{- 1}$ ( $λ$ is the London penetration depth) and has been used to derive the force exerted by the electrons on a moving flux tube. By calculating the current-current response, I find that $v_{p} \neq = u_{e}$ for $l^{- 1} < q ≪ λ^{- 1}$ ( $l$ is the electron mean free path). I show that at typical realistic parameters the electric field induced by a moving (relative to the electrons) flux tube is not screened by the electron currents. The implication is that the existing picture of the momentum exchange between the electrons and the flux tubes must be reassessed.
Comments:
5 pages, 5 figures. Revised 2nd version
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Superconductivity (cond-mat.supr-con)
arXiv:
2305.12882 [pdf]
PRC(2023)·2 citations
05
[Submitted on 22 May 2023]
Study of np-scattering for S, P and D Waves using Deng-Fan Potential by Phase Function Method
Ayushi Awasthi · O.S.K.S Sastri
In this paper, the np - scattering phase shifts and cross section for S,P and D partial waves have been obtained for energies below the pion threshold, by considering Deng-Fan potential as model of interaction. The radial time independent Schrödinger equation has been analytically solved using Nikiforov - Uvarov method to obtain the energy expression for ground state of np system. Utilising this, the scattering phase shifts for $^{3} S_{1}$ have been obtained using phase function method. The phase equations for various scattering states $^{1} S_{0}$ , $^{1} P_{1}$ , $^{3} P_{0, 1, 2}$ , $^{1} D_{2}$ , and $^{3} D_{1, 2, 3}$ have been numerically solved for obtaining corresponding scattering phase shifts and their respective partial cross section. The total scattering cross sections computed at various energies are found to be closely matching with experimental data. The low energy scattering parameters determined from scattering phase shifts of $^{3} S_{1}$ and $^{1} S_{0}$ are reasonably close to experimental ones. Hence, Deng-Fan potential is a good phenomenological potential to understand the np - scattering system.
Comments:
11 pages, 4 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2305.13205 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Modified approach for accounting for dissipation in theoretical description of fusion of complex nuclei

Charge radii of atomic nuclei and shell effects

Singlet cross section and the tensor interaction in p​p→ΛˉΛ

On the screening condition in the core of neutron stars

Study of np-scattering for S, P and D Waves using Deng-Fan Potential by Phase Function Method

Affiliations

Singlet cross section and the tensor interaction in $p p \to Λ ˉ Λ$