Nuclear Theory·nucl-th

Thursday·May 20, 2021

9 papers—6 primary·3 cross-listed

01
[Submitted on 19 May 2021]
Reaction cross section of proton scattering consistent with PREX-II (published in Results in Physics)
Tomotsugu Wakasa · Shingo Tagami · Jun Matsui · Masanobu Yahiro · Maya Takechi
Background: The neutron skin thickness $R_{skin}^{PV}$ of PREX-II is presented in Phys. Rev. Lett. {\bf 126}, 172502 (2021). The reaction cross section $σ_{R}$ is useful to determine the matter radius $R_{m}$ and $R_{skin}$ . For proton scattering, the reaction cross section $σ_{R}$ are available for $E_{in} > 400$ MeV. Method and results: We determine $R_{n}^{exp} = 5.727 \pm 0.071$ fm and $R_{m}^{exp} = 5.617 \pm 0.044$ fm from $R_{p}^{exp}$ = 5.444 fm and $R_{skin}^{PV}$ . The $R_{p}^{GHFB}$ calculated with D1S-GHFB with the angular momentum projection (AMP). agrees with $R_{p}^{exp}$ . The neutron density calculated with GHFB+AMP is scaled so as to $R_{n}^{scaling} = 5.727$ fm. The Love-Franey $t$ -matrix model with the scaled densities reproduces the data on $σ_{R}$ . Aim: Our aim is to find the $σ_{R}$ of proton scattering consistent with $R_{skin}^{PV}$ . Conclusion: The $σ_{R}$ of proton scattering consistent with $R_{skin}^{PV}$ are $σ_{R}^{exp}$ at $E_{in} = 534.1, 549, 806$ MeV.
Comments:
arXiv admin note: text overlap with arXiv:2010.02450
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.08903 [pdf]
0 citations
02
[Submitted on 19 May 2021]
Ab initio nuclear structure via quantum adiabatic algorithm
Weijie Du🇺🇸 · James P. Vary🇺🇸 · Xingbo Zhao🇨🇳 · Wei Zuo🇨🇳
Background: Solving nuclear many-body problems with an ab initio approach is widely recognized as a computationally challenging problem. Quantum computers offer a promising path to address this challenge. There are urgent needs to develop quantum algorithms for this purpose. Objective: In this work, we explore the application of the quantum algorithm of adiabatic state preparation with quantum phase estimation in ab initio nuclear structure theory. We focus on solving the low-lying spectra (including both the ground and excited states) of simple nuclear systems. Ideas: The efficiency of this algorithm is hindered by the emergence of small energy gaps (level crossings) during the adiabatic evolution. In order to improve the efficiency, we introduce techniques to avoid level crossings: 1) by suitable design of the reference Hamiltonian; 2) by insertions of perturbation terms to modify the adiabatic path. Results: We illustrate this algorithm by solving the deuteron ground state energy and the spectrum of the deuteron bounded in a harmonic oscillator trap implementing the IBM Qiskit quantum simulator. The quantum results agree well the classical results obtained by matrix diagonalization. Outlook: With our improvements to the efficiency, this algorithm provides a promising tool for investigating the low-lying spectra of complex nuclei on future quantum computers.
Comments:
19 pages, 4 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2105.08910 [pdf]
12 citations
03
[Submitted on 19 May 2021]
Application of machine learning in the determination of impact parameter in the $^{132}$ Sn+ $^{124}$ Sn system
Fupeng Li · Yongjia Wang · Zepeng Gao · Pengcheng Li · Hongliang Lv · Qingfeng Li · C.Y.Tsang · M.B.Tsang
Background: $^{132}$ Sn+ $^{124}$ Sn collisions at the beam energy of 270 MeV $/$ nucleon have been performed at the Radioactive Isotope Beam Factory (RIBF) in RIKEN to investigate the nuclear equation of state. Reconstructing impact parameter is one of the important tasks in the experiment as it relates to many observables. Purpose: In this work, we employ three commonly used algorithms in machine learning, the artificial neural network (ANN), the convolutional neural network (CNN) and the light gradient boosting machine (LightGBM), to determine impact parameter by analyzing either the charged particles spectra or several features simulated with events from the ultra-relativistic quantum molecular dynamics (UrQMD) model. Method: To closely imitate experimental data and investigate the generalizability of the trained machine learning algorithms, incompressibility of nuclear equation of state and the in-medium nucleon-nucleon cross sections are varied in the UrQMD model to generate the training data. Results: The mean absolute error $Δ b$ between the true and the predicted impact parameter is smaller than 0.45 fm if training and testing sets are sampled from the UrQMD model with the same parameter set. However, if training and testing sets are sampled with different parameter sets, $Δ b$ would increase to 0.8 fm. Conclusion: The generalizability of the trained machine learning algorithms suggests that these machine learning algorithms can be used reliably to reconstruct impact parameter in experiment.
Comments:
9 pages,9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.08912 [pdf]
PRC(2021)·44 citations
04
[Submitted on 19 May 2021]
Isotopic shift and search of magic number in the superheavy region
Jeet Amrit Pattnaik🇮🇳 · R. N. Panda🇮🇳 · M. Bhuyan🇲🇾 · S. K. Patra🇮🇳
The ground state bulk properties such as binding energy, root-mean-square radius, pairing energy, nuclear density distributions, and single-particle energies are calculated for the isotopic chain of Ca, Sn, Pb, and Z = 120 nuclei. The relativistic mean-field with recently developed G3, IOPB-1, and Relativistic-Hartree-Bogoliubov with density-dependent DD-ME1 and DD-ME2 parameter sets are used in the present analysis. The respective shifts over the isotopic chain for the structural observables and surface property like symmetry energy are also estimated using a three-point method, which is crucial for the systematic analysis of the shell/sub-shell closure. The calculated results are compared with the available experimental data for various bulk properties, wherever available. A multiple isotopic shifts leads to the shell/sub-shell closure at N = (20 \& 28), (50 \& 82), and 126 for Ca, Sn, and Pb isotopes, respectively, are observed. The analysis also supports the neutron magic at N = 40 and 184 for highly neutron-rich $^{60}$ Ca, and $^{304}$ 120, predicted to be the next double magic beyond $^{208}$ Pb, respectively. Observing the occupancy number, we notice the higher neutron orbitals are mostly occupied before the lower one, which causes the kinks at neutron magic with an amalgam in the isotopic chain trend above nuclei. We also notice the correlation between the occupation probabilities and the magicity of a nucleus and vice-versa.
Comments:
10 pages,14 figures,1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.08999 [pdf]
Phys.Scripta(2021)·23 citations
05
[Submitted on 19 May 2021]
Meson-exchange currents and superscaling analysis with relativistic effective mass of quasielastic electron scattering from $^{12}$ C
V.L. Martinez-Consentino🇪🇸 · I. Ruiz Simo🇪🇸 · J.E. Amaro🇪🇸
We reanalyze the scaling properties of inclusive quasielastic electron scattering from $^{12}$ C by subtracting from the data the effects of two-particle emission. A model of relativistic meson-exchange currents (MEC) is employed within the mean field theory of nuclear matter, with scalar and vector potentials that induce an effective mass and a vector energy to the nucleons. A new phenomenological quasielastic scaling function is extracted from a selection of the data after the subtraction of the 2p-2h contribution. The resulting superscaling approach with relativistic effective mass (SuSAM*) can be used to compute the genuine quasielastic cross section without contamination of the 2p-2h channel that can then be added separately to obtain the total quasielastic plus two-nucleon emission response.
Comments:
13 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2105.09079 [pdf]
PRC(2021)·25 citations
06
[Submitted on 19 May 2021]
Fission fragment distributions of neutron-rich nuclei based on Langevin calculations: toward r-process simulations
Mizuki Okubayashi🇯🇵 · Shoya Tanaka🇯🇵 · Yoshihiro Aritomo🇯🇵 · Shoma Ishizaki🇯🇵 · Shota Amano🇯🇵 · Nobuya Nishimura🇯🇵
The nuclear fission of very neuron-rich nuclei related to the r-process is essential for the termination of nucleosynthesis flows on the nuclear chart and the final abundances. Nevertheless, most of the available fission data for the r-process calculations are based on theory predictions, including phenomenological treatments. In this study, we calculated a series of nuclear fission distribution for neutron-rich nuclei away from the beta-stability line. As most of these nuclei are experimentally unknown, we are based on theoretical calculations based on the dynamical fission model with the Langevin method. We performed fission distribution calculations for neutron-rich actinoid nuclei, applicable to the r-process nucleosynthesis simulations. In the present paper, we compared the obtained mass and charge distributions with experimental data. We also show the results of the systematic behaviour of mass distribution for neutron-rich U and Fm isotopes.
Comments:
6 pages, 5 figures, to be published in the conference proceedings of "Symposium on Nuclear Data 2020"
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2105.09272 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Reaction cross section of proton scattering consistent with PREX-II (published in Results in Physics)

Ab initio nuclear structure via quantum adiabatic algorithm

Application of machine learning in the determination of impact parameter in the 132Sn+124Sn system

Isotopic shift and search of magic number in the superheavy region

Meson-exchange currents and superscaling analysis with relativistic effective mass of quasielastic electron scattering from 12C

Fission fragment distributions of neutron-rich nuclei based on Langevin calculations: toward r-process simulations

Affiliations

Application of machine learning in the determination of impact parameter in the $^{132}$ Sn+ $^{124}$ Sn system

Meson-exchange currents and superscaling analysis with relativistic effective mass of quasielastic electron scattering from $^{12}$ C