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Machine learning the nuclear mass

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nuclear Science and Techniques 2021年第10期32卷 88-100页

作者： Ze-Peng Gao Yong-Jia Wang Hong-Liang Lu Qing-Feng Li Cai-Wan Shen Ling Liu College of Physics Science and Technology Shenyang Normal UniversityShenyang 110034China School of Science Huzhou UniversityHuzhou 313000China HiSilicon Research Department Huawei Technologies Co.Ltd.Shenzhen 518000China Institute of Modern Physics Chinese Academy of ScienceLanzhou 730000China

Background:The masses of-2500 nuclei have been measured experimentally;however,>7000 isotopes are predicted to exist in the nuclear landscape from H(Z=1)to Og(Z=118)based on various theoretical *** the mass of the remaining isotopes is a popular topic in nuclear *** learning has served as a powerful tool for learning complex representations of big data in many ***:We use Light Gradient Boosting Machine(LightGBM),which is a highly efficient machine learning algorithm,to predict the masses of unknown nuclei and to explore the nuclear landscape on the neutron-rich side from learning the measured nuclear ***:Several characteristic quantities(e.g.,mass number and proton number)are fed into the LightGBM algorithm to mimic the patterns of the residual δ(Z,A)between the experimental binding energy and the theoret-ical one given by the liquid-drop model(LDM),Duflo–Zucker(DZ,also dubbed DZ28)mass model,finite-range droplet model(FRDM,also dubbed FRDM2012),as well as the Weizsacker–Skyrme(WS4)model to refine these mass ***:By using the experimental data of 80%of known nuclei as the training dataset,the root mean square devia-tions(RMSDs)between the predicted and the experimental binding energy of the remaining 20%are approximately 0.234±0.022,0.213±0.018,0.170±0.011,and 0.222±0.016 MeV for the LightGBM-refined LDM,DZ model,WS4 model,and FRDM,*** values are approximately 90%,65%,40%,and 60%smaller than those of the corresponding origin mass *** RMSD for 66 newly measured nuclei that appeared in AME2020 was also significantly *** one-neutron and two-neutron separation energies predicted by these refined models are consistent with several theoretical predictions based on various physical *** addition,the two-neutron separation energies of several newly measured nuclei(e.g.,some isotopes of Ca,Ti,Pm,and Sm)pre-dicted with LightGBM-refined mass models are also in good agreement with

关键词： nuclear mass Machine learning Binding energy Separation energy

Ability of the radial basis function approach to extrapolate nuclear mass

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Communications in Theoretical Physics 2021年第9期73卷 79-85页

作者： Tao Li Haiwan Wei Min Liu Ning Wang Department of Physics Guangxi Normal UniversityGuilin541004China Guangxi Key Laboratory of nuclear Physics and Technology Guilin541004China

The ability of the radial basis function(RBF)approach to extrapolate the masses of nuclei in neutron-rich and superheavy regions is investigated in combination with the Duflo-Zuker(DZ31),Hartree–Fock-Bogoliubov(HFB27),finite-range droplet model(FRDM12)and Weizsäcker-Skyrme(WS4)mass *** is found that when the RBF approach is employed with a simple linear basis function,different mass models have different performances in extrapolating nuclear masses in the same region,and a single mass model may have different performances when it is used to extrapolate nuclear masses in different *** WS4 and FRDM12 models(two macroscopic–microscopic mass models),combined with the RBF approach,may perform better when extrapolating the nuclear mass in the neutron-rich and superheavy regions.

关键词： extrapolation ability nuclear mass radial basis function root-mean-square deviation mass model

Principal components of nuclear mass models

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 65-71页

作者： Xin-Hui Wu Pengwei Zhao Department of Physics Fuzhou UniversityFuzhou 350108China State Key Laboratory of nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China

Principal component analysis(PCA)is employed to extract the principal components(PCs)present in nuclear mass models for the first *** effects from different nuclear mass models are reintegrated and reorganized in the extracted *** PCs are recombined to build new mass models,which achieve better accuracy than the original theoretical mass *** comparison indicates that using the PCA approach,the effects contained in different mass models can be collaborated to improve nuclear mass predictions.

关键词： nuclear mass principal component analysis nuclear models statistical methods

Improved mass relations of mirror nuclei

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nuclear Science and Techniques 2024年第9期35卷 178-185页

作者： Cheng Xu Man Bao Department of Physics University of Shanghai for Science and TechnologyShanghai 200093China

In this study,we revisit the previous mass relations of mirror nuclei by considering 1/N-and 1/Z-dependent terms and the shell effect across a *** root-mean-squared deviation is 66 keV for 116 nuclei with neutron number N≥10,as com-pared with experimental data compiled in the AME2020 *** predicted mass excesses of 173 proton-rich nuclei,including 98 unknown nuclei,are tabulated in the Supplemental Material herein with competitive accuracy.

关键词： nuclear mass Mirror nuclei Proton-rich nuclei

Exploring the uncertainties in theoretical predictions of nuclear β-decay half-lives

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Chinese Physics C 2021年第4期45卷 273-278页

作者： M.Shi J.Y.Fang Z.M.Niu School of Mathematics and Physics Anhui Jianzhu UniversityHefei 230601China Key Laboratory of Architectural Acoustic Environment of Anhui Higher Education Institutes Hefei 230601China Key Laboratory of Advanced Electronic Materials and Devices Anhui Jianzhu UniversityHefei230601China School of Physics and Materials Science Anhui UniversityHefei 230601China Institute of Physical Science and Information Technology Anhui UniversityHefei 230601China

nuclear β-decay half-lives are predicted based on an empirical formula and the mass predictions from various nuclear *** is found that the empirical formula can reproduce the nuclearβ-decay half-lives well,especially for short-lived nuclei with T_(1/2)<*** theoretical half-life uncertainties fromβ-decay energies and the parameters of the empirical formula are further *** is found that the uncertainties of the half-lives are relatively large for heavy nuclei and nuclei near the neutron-drip *** nuclei on the r-process path,the uncertainties for those with N=126 are about one order of magnitude,which are much larger than the uncertainties for those with N=50 and ***,theoretical uncertainties from the parameters of the empirical formula are relatively small for the nuclei on the r-process path,which indicates that the empirical formula is very suitable for predicting theβ-decay half-lives in r-process simulations.

关键词： βdecay nuclear mass r process

Examination of n-T_(9) conditions required by N=50,82,126 waiting points in r-process

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Communications in Theoretical Physics 2021年第10期73卷 147-157页

作者： Nguyen Duy Ly Nguyen Ngoc Duy Nguyen Kim Uyen Vinh N T Pham Faculty of Fundamental Sciences Vanlang UniversityHo Chi Minh City 700000Vietnam Department of Physics Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Physics Ho Chi Minh City University of EducationHo Chi Minh City 700000Vietnam

We examined the conditions of neutron density(n) and temperature(T9) required for the N = 50, 82,and 126 isotopes to be waiting points(WP) in the r-process. The nuclear mass based on experimental data presented in the AME2020 database(AME and AME ± Δ) and that predicted using FRDM,WS4, DZ10, and KTUY models were employed in our estimations. We found that the conditions required by the N = 50 WP significantly overlap with those required by the N = 82 ones, except for the WS4 model. In addition, the upper(or lower) bounds of the n-T9 conditions based on the models are different from each other due to the deviations in the two-neutron separation *** standard deviations in the nuclear mass of 108 isotopes in the three N = 50, 82, and 126 groups are about rms = 0.192 and 0.434 Me V for the pairs of KTUY-AME and WS4-KTUY models,respectively. We found that these mass uncertainties result in a large discrepancy in the nn-T_(9) conditions, leading to significant differences in the conditions for simultaneously appearing all the three peaks in the r-process abundance. The newly updated FRDM and WS4 calculations can give the overall conditions for the appearance of all the peaks but vice versa for their old versions in a previous study. The change in the final r-process isotopic abundance due to the mass uncertainty is from a few factors to three orders of magnitude. Therefore, accurate nuclear masses of the r-process key nuclei, especially for 76 Fe,81Cu,127Rh,132Cd,192Dy, and 197Tm, are highly recommended to be measured in radioactive-ion beam facilities for a better understanding of the r-process evolution.

关键词： neutron capture r-process nuclear mass isotopic abundance precise mass measurement

Possible existence of bound nuclei beyond neutron drip lines driven by deformation

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Chinese Physics C 2021年第10期45卷 1-6页

作者： Xiao-Tao He Chen Wang Kai-Yuan Zhang Cai-Wan Shen College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China School of Science Huzhou UniversityHuzhou 313000China

Based on the relativistic calculations of the nuclear masses in the transfermium region from No(Z=102)to Ds(Z=110)using the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc),the possible existence of bound nuclei beyond the neutron drip lines is *** two-neutron and multi-neutron emission bound nuclei beyond the primary neutron drip line of N=258 are predicted in Z=106,108,and 110 isotopes.A detailed microscopic mechanism investigation reveals that nuclear deformation plays a vital role in the existence of bound nuclei beyond the drip ***,not only the quadrupole deformation β_(2) but also the higher orders of deformation are indispensable in the reliable description of the phenomenon of reentrant binding.

关键词： neutron drip line transfermium nuclei deformation DRHBc theory reentrant binding nuclear mass

Ground-state mass of ^(22)Al and test of state-of-the-art ab initio calculations

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Chinese Physics C 2024年第3期48卷 72-78页

作者：孙铭泽于越王新鹏王猛李健国张玉虎 K.Blaum 陈祖毅陈瑞九邓涵宇付超义葛文文黄文嘉焦红扬李红蕙李宏福罗胤芳廖挺 YuALitvinov 司敏帅鹏史金阳王茜邢元明徐星徐瑚珊许甫荣袁琪 T.Yamaguchi 颜鑫亮杨建成原有进周小红周旭张敏曾奇 CAS Key Laboratory of High Precision nuclear Spectroscopy Institute of Modern PhysicsChinese Academy of SciencesLanzhou 730000China School of nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Max-Planck-Institut für Kernphysik Saupfercheckweg 169117 HeidelbergGermany GSI Helmholtzzentrum für Schwerionenforschung Planckstraße 164291 DarmstadtGermany Advanced Energy Science and Technology Guangdong Laboratory Huizhou516007China State Key Laboratory of nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China Department of Physics Saitama UniversitySaitama 338-8570Japan School of nuclear Science and Engineering East China University of TechnologyNanchang 330013China

The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed Bρ-defined isochronous mass spectrometry method at the cooler storage ring in *** new mass excess value allowed us to determine the excitation energies of the two low-lying 1+states in ^(22)Al with significantly reduced uncertainties of 51 *** compared to the analogue states in its mirror nucleus ^(22)F,the mirror energy differences of the two 1^(+)states in the ^(22)Al-^(22)F mirror pair are determined to be−625(51)keV and−330(51)*** excitation energies and mirror energy differences are used to test the state-of-the-art ab initio valence-space in-medium similarity renormalization group calculations with four sets of interactions derived from the chiral effective field *** mechanism leading to the large mirror energy differences is investigated and attributed to the occupation of theπs_(1/2) orbital.

关键词： nuclear mass Bρ-defined IMS mirror energy difference ab initio VS-IMSRG calculations chiral interactions

Precision mass measurements of short-lived nuclides at HIRFL-CSR in Lanzhou

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Frontiers of physics 2018年第6期13卷 161-180页

作者： Ming-Ze Sun Xiao-Hong Zhou Meng Wang Yu-Hu Zhang Yu. A. Litvinov Key Laboratory of High Precision nuclear Spectroscopy and Center for nuclear Matter Science Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China University of Chinese Academy of Sciences Beijing 100049 China GSI Helmholtzzentrum fiir Schwerionenforschung Planckstraβe 1 64291 Darmstadt Germany

In recent years, extensive short-lived nuclear mass measurements have been carried out at the Heavy- Ion Research Facility （HIRFL） in Lanzhou using Isochronous mass Spectrometry （IMS）. The obtained mass values have been successfully applied to nuclear structure and astrophysics studies. In this contribution, we give a brief introduction to the nuclear mass measurements at HIRFL-CSR facility. Main technical developments are described and recent results are summarized. Furthermore, we envision the future perspective for the next-generation storage ring facility HIAF in Huizhou.

关键词： nuclear mass short-lived nuclei storage ring isochronous mass spectrometry