arXiv subjects

D. -L. Fang

Publications and source records attributed to D. -L. Fang.

6 recordsLinked to original sources

arXiv2023

$0νββ$-decay nuclear matrix elements in self-consistent Skyrme quasiparticle random phase approximation: uncertainty from pairing interaction

The uncertainty in the nuclear matrix elements (NMEs) of $0νββ$ decay for $^{76}$Ge, $^{82}$Se, $^{128}$Te, $^{130}$Te, and $^{136}$Xe in the self-consistent quasiparticle random phase approximation (QRPA) method is investigated by using eighteen Skyrme interactions supplemented with either a volume- or surface-type of pairing interactions. The NMEs for the isotopes concerned (except $^{136}$Xe) are less sensitive to the particle-hole ($ph$) interactions, while strongly dependent on the employed isovector particle-particle ($pp$) pairing interactions even though the pairing strengths are optimized to the same pairing gap. The results indicate that a precise determination of the isovector $pp$ pairing interaction in the Skyrme energy density functional is of importance to reduce the uncertainty in the NMEs within the QRPA framework.

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arXiv2015

The impact of individual nuclear masses on $r$-process abundances

We have performed for the first time a comprehensive study of the sensitivity of $r$-process nucleosynthesis to individual nuclear masses across the chart of nuclides. Using the latest version (2012) of the Finite-Range Droplet Model, we consider mass variations of $\pm0.5$ MeV and propagate each mass change to all affected quantities, including $Q$-values, reaction rates, and branching ratios. We find such mass variations can result in up to an order of magnitude local change in the final abundance pattern produced in an $r$-process simulation. We identify key nuclei whose masses have a substantial impact on abundance predictions for hot, cold, and neutron star merger $r$-process scenarios and could be measured at future radioactive beam facilities.

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arXiv2014

Nuclear masses near $N=82$ that influence $r$-process abundances

Nuclear masses are one of the key ingredients of nuclear physics that go into astrophysical simulations of the $r$ process. Nuclear masses effect $r$-process abundances by entering into calculations of Q-values, neutron capture rates, photo-dissociation rates, beta-decay rates, branching ratios and the properties of fission. Most of the thousands of short-lived neutron-rich nuclei which are believed to participate in the $r$ process lack any experimental verification, thus the identification of the most influential nuclei is of paramount importance. We have conducted mass sensitivity studies near the $N=82$ closed shell in the context of a main $r$-process. Our studies take into account how an uncertainty in a single nuclear mass propagates to influence the relevant quantities of neighboring nuclei and finally to $r$-process abundances. We identify influential nuclei in various astrophysical conditions using the FRDM mass model. We show that our conclusions regarding these key nuclei are still retained when a superposition of astrophysical trajectories is considered.

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arXiv2014

The impact of nuclear masses near $N=82$ on $r$-process abundances

We have performed for the first time a complete $r$-process mass sensitivity study in the $N=82$ region. We take into account how an uncertainty in a single nuclear mass propagates to influence important quantities of neighboring nuclei, including Q-values and reaction rates. We demonstrate that nuclear mass uncertainties of $\pm0.5$ MeV in the $N=82$ region result in up to an order of magnitude local change in $r$-process abundance predictions. We identify key nuclei in the study whose mass has a substantial impact on final $r$-process abundances and could be measured at future radioactive beam facilities.

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arXiv2014

Benchmarking nuclear models for Gamow-Teller response

A comparative study of the nuclear Gamow-Teller response (GTR) within conceptually different state-of-the-art approaches is presented. Three nuclear microscopic models are considered: (i) the recently developed charge-exchange relativistic time blocking approximation (RTBA) based on the covariant density functional theory, (ii) the shell model (SM) with an extended "jj77" model space and (iii) the non-relativistic quasiparticle random-phase approximation (QRPA) with a Brueckner G-matrix effective interaction. We study the physics cases where two or all three of these models can be applied. The Gamow-Teller response functions are calculated for 208-Pb, 132-Sn and 78-Ni within both RTBA and QRPA. The strengths obtained for 208-Pb are compared to data that enables a firm model benchmarking. For the nucleus 132-Sn, also SM calculations are performed within the model space truncated at the level of a particle-hole (ph) coupled to vibration configurations. This allows a consistent comparison to the RTBA where ph+phonon coupling is responsible for the spreading width and considerable quenching of the GTR. Differences between the models and perspectives of their future developments are discussed.

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arXiv2013

Nuclear shell structure and response toward the limits of mass, temperature and isospin

We present a short overview of our recent theoretical developments aiming at the description of exotic nuclear phenomena to be reached and studied at the next-generation radioactive beam facilities. Applications to nuclear shell structure and response of nuclei at the limits of their existence, with a special focus on the physics cases of astrophysical importance, are discussed.

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