nucl-th digest · Oct 24, 2023

[Submitted on 21 Oct 2023]

Many-channel microscopic theory of resonance states and scattering processes in $^{9}$ Be and $^{9}$ B

Yu. A. Lashko · V. S. Vasilevsky · V. I. Zhaba

We present a many-channel microscopic model that extends the three-cluster model previously formulated in \cite{2009NPA...V37}. This extended model incorporates multiple three-cluster configurations, which are subsequently reduced to a comprehensive set of binary channels. These channels dictate the dynamics of various nuclear processes and the resonance structure of a compound nucleus across a broad energy spectrum. The application of this model focuses on investigating the nature of high-energy resonance states in $^{9}$ Be and $^{9}$ B, as well as the astrophysical $S$ -factors for the reactions $^{7}$ Li $(d, n) α α$ and $^{7}$ Be $(d, p) α α$ , particularly pertinent to the cosmological lithium problem. Parameterization of resonance states is performed across a wide range of total angular momenta and includes states of both positive and negative parity. Dominant decay channels are identified for each resonance state. Detailed analysis of astrophysical $S$ factors resulting from deuteron interactions with $^{7}$ Li and $^{7}$ Be is conducted within an energy range from zero to 2 MeV. Four exit channels in $^{9}$ Be ( $^{8}$ Be( $0^{+}$ ) $+ n$ , $^{8}$ Be( $2^{+}$ ) $+ n$ , $^{5}$ He( $3/ 2^{-}$ ) $+ α$ , $^{5}$ He( $1/ 2^{-}$ ) $+ α$ ) and four in $^{9}$ B ( $^{8}$ Be( $0^{+}$ ) $+ p$ , $^{8}$ Be( $2^{+}$ ) $+ p$ , $^{5}$ Li( $3/ 2^{-}$ ) $+ α$ , $^{5}$ Li( $1/ 2^{-}$ ) $+ α$ ) are considered. A clear hierarchy of reactions is established for the energy range 0 $\leq E <$ 1.0 MeV. Notably, reactions $^{7}$ Li $+ d =^{8}$ Be( $0^{+}$ ) $+ n$ and $^{7}$ Be $+ d =^{8}$ Be( $0^{+}$ ) $+ p$ substantially dominate over all other reactions within this energy range. The model satisfactory describes the experimental astrophysical $S$ factors for these reactions.

Comments:: 36 pages, 23 figures, to be submitted to Phys. Rev. C
Subjects:: Nuclear Theory (nucl-th)
arXiv:: 2310.13979 [pdf]

PRC(2024)·8 citations

The optical potentials and nuclear reaction cross sections for the

n

^{12}

C and

N

^{12}

C scattering

In this work we extend a previously derived

n

^{9}

Be optical potential up to 500 MeV and apply it to the system

n

^{12}

C, finding excellent results for the energy dependence of the total cross sections. Results obtained with a standard optical model calculation are compared to those from the eikonal formalism in order to asses the accuracy of the latter as a function of the nucleon incident energy. For comparison, single folded (s.f.) nucleon-target potentials are also obtained using

^{12}

C densities from different models. These potentials are sensitive to the density used and none of them reproduce the characteristics of the phenomenological potential nor the cross section results. We then calculate nucleus-nucleus (

N N

) potentials and total reaction cross sections for some "normal" and exotic projectile nuclei on

^{12}

C within the eikonal formalism. We find that single folded (S.F.) projectile-target imaginary potentials and double folded (D.F.) potentials can produce similar energy dependence of the reaction cross sections but the S.F. results agree better with experimental data provided the radius parameter of the phenomenological

n

-target potential is allowed to be energy dependent. We conclude that the results previously obtained for a

^{9}

Be target are quite general, at least for light systems, and that a S.F.

N N

potential built on a phenomenological nN potential can constitute an interesting and useful alternative to D.F. potentials.

Comments:: 11 pages, 8 figures
Subjects:: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:: 2310.14118 [pdf]

PRC(2023)·2 citations

Tuesday·October 24, 2023

Many-channel microscopic theory of resonance states and scattering processes in $^{9}$ Be and $^{9}$ B

The optical potentials and nuclear reaction cross sections for the $n$ - $^{12}$ C and $N$ - $^{12}$ C scattering

Affiliations

Many-channel microscopic theory of resonance states and scattering processes in 9Be and 9B

The optical potentials and nuclear reaction cross sections for the n-12C and N-12C scattering

Affiliations

Many-channel microscopic theory of resonance states and scattering processes in $^{9}$ Be and $^{9}$ B

The optical potentials and nuclear reaction cross sections for the $n$ - $^{12}$ C and $N$ - $^{12}$ C scattering