Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particu...Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particularly at the microscale.Here,we propose a novel method,vortex Mössbauer spectroscopy,for probing chiral structures.By leveraging the orbital angular momentum carried by vortex beams,this approach achieves high precision in detecting chiral structures at scales ranging from nanometers to hundreds of nanometers.Our simulation shows the ratio of characteristic lines in the Mössbauer spectra of ^(57)Fe under vortex beams exhibits differences of up to four orders of magnitude for atomic structures with different arrangements.Additionally,simulations reveal the response of ^(229m)Th chiral structures to vortex beams with opposite angular momenta differs by approximately 49-fold.These significant spectral variations indicate that this new vortex Mössbauer probe holds great potential for investigating the microscopic chiral structures and interactions of matter.展开更多
本研究基于三个具有代表性的理论模型:相对论连续谱Hartree-Bogoliubov (RCHB)理论,相对论平均场(RMF)理论,Skyrme-Hartree-Fock-Bogoliubov (SHFB)模型,首先介绍了人工神经网络(ANN)方法,计算出了三个模型的单核子分离能的理论预测值...本研究基于三个具有代表性的理论模型:相对论连续谱Hartree-Bogoliubov (RCHB)理论,相对论平均场(RMF)理论,Skyrme-Hartree-Fock-Bogoliubov (SHFB)模型,首先介绍了人工神经网络(ANN)方法,计算出了三个模型的单核子分离能的理论预测值。随后利用神经网络对单核子分离能的理论值进行了优化训练,降低了单核子分离能的理论预测值与实验值之间的均方根偏差(RMSD),并在此基础上进行了两种分区优化,分别为质子和中子的幻数分区,分区优化训练后进一步降低了RMSD。单核子分离能分区训练后的RMSD比整体直接训练的效果更好,特别能显著降低轻核区的RMSD,单中子分离能进行中子幻数分区训练的效果更好,单质子分离能进行质子幻数分区训练的效果更好。This research is based on three representative theoretical models: the Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, Relativistic Mean Field (RMF) theory, and Skyrme-Hartree-Fock-Bogoliubov (SHFB) model. First, the Artificial Neural Network (ANN) method was introduced to calculate theoretical predictions of single-nucleon separation energies for these three models. Subsequently, the neural network was employed to optimize and train the theoretical values of single-nucleon separation energies, reducing the root mean square deviation (RMSD) between theoretical predictions and experimental values. Two partitioning optimization schemes were then implemented: proton magic number partitioning and neutron magic number partitioning. The partitioned optimization training further reduced RMSD values. The partitioned training of single-nucleon separation energies demonstrated better performance than direct global training, particularly in significantly reducing RMSD in the light nuclei region. Specifically, neutron magic number partitioning showed superior effectiveness for optimizing single-neutron separation energies, while proton magic number partitioning yielded better results for single-proton separation energies.展开更多
Within the context of the proton-neutron quasi-particle random phase approximation(pn-QRPA)model and TALYS v1.96 code,the radiative capture(^(99)Tc(n,γ)^(100)Tc)and stellar weak interaction(^(99)Tc→^(99)Ru+e^(−)+ν_...Within the context of the proton-neutron quasi-particle random phase approximation(pn-QRPA)model and TALYS v1.96 code,the radiative capture(^(99)Tc(n,γ)^(100)Tc)and stellar weak interaction(^(99)Tc→^(99)Ru+e^(−)+ν_(e))rates were computed during thermal pulses operating in asymptotic giant branch stars.The Maxwellian average cross-section(MACS)and neutron capture rates for the^(99)Tc(n,γ)^(100)Tc process are analyzed within the context of statistical code TALYS v1.96.The effect of nuclear level density(NLD)andγ-strength functions on MACS and neutron capture rates has been examined.The model-based computations for MACS provided an insightful contrast to prior investigated findings.The sensitivity of stellar weak interaction rates to different densities and temperatures is investigated using the pn-QRPA model.The impact of thermally populated excited states on electron emission(β^(−))rates in^(99)Tc is extensively examined.Additionally,a comparison is made between the study of the stellarβ^(−)decay rates and the thermal neutron capture rates.It is found that at T_(9)=0.26 the thermal neutron capture rates(λ_((n,γ)))and the temperature dependent stellarβ^(−)decay rates( λ_(β-))cross each other.However,at higher temperatures,theλ(n,γ)are found to be higher than λ_(β-).展开更多
An improved formula considering the deformation effect for the α-decay half-lives is proposed based on WKB barrier penetrability.Using the quadrupole deformation values of the daughter nuclei obtained from the WS4 an...An improved formula considering the deformation effect for the α-decay half-lives is proposed based on WKB barrier penetrability.Using the quadrupole deformation values of the daughter nuclei obtained from the WS4 and FRDM models in the improved formula,the root mean square deviation(RMSD)between the calculated results and experimental data decreased from 0.456 to 0.413 and 0.415,respectively.Although the improved formula did not significantly reduce the overall RMSD,it produced results that better matched the experimental values for nuclei with larger deformations.Additionally,eXtreme Gradient Boosting(XGBoost)models were employed to further reduce the deviations between the calculated α-decay half-lives and experimental data,with the corresponding RMSDs decreasing from 0.413 to 0.295 and from 0.415 to 0.302,respectively.Furthermore,the improved empirical formula and XGBoost models were used to predict the α-decay half-lives of nuclei with Z=117,118,119,and 120.The results suggest that N=184 is the magic number.展开更多
Highly oriented pyrolytic graphite (HOPG) is frequently adopted as the reaction target in12C+12C fusion reaction experiments owing to its superior purity.In this study,we investigate the reaction yield dependence on t...Highly oriented pyrolytic graphite (HOPG) is frequently adopted as the reaction target in12C+12C fusion reaction experiments owing to its superior purity.In this study,we investigate the reaction yield dependence on the accumulated beam dose on HOPG target using a novel detection system consisting of a time-projection chamber and silicon array.The reaction yields are significantly reduced under intense beam bombardment owing to radiation damage to the HOPG surface.The α_(0) and p_(0,1) yields decrease by 51.5% and 25%,respectively,when the ^(12)C^(2+) beam dose accumulates at 5 C.Using the novel detection system and HOPG target,the α0yield is determined to be 2.68_(-1.69)^(+4.69)×10^(-17/12) C after correcting for the yield loss due to radiation damage.Our result represents the highest sensitivity achieved to date in direct measurements of ^(12)C(12C,α_(0))^(20)Ne.展开更多
A machine learning approach based on Bayesian neural networks was developed to predict the complete fusion cross-sections of weakly bound nuclei.This method was trained and validated using 475 experimental data points...A machine learning approach based on Bayesian neural networks was developed to predict the complete fusion cross-sections of weakly bound nuclei.This method was trained and validated using 475 experimental data points from 39 reaction systems induced by ^(6,7)Li,^(9)Be,and ^(10)B.The constructed Bayesian neural network demonstrated a high degree of accuracy in evaluating complete fusion cross-sections.By comparing the predicted cross-sections with those obtained from a single-barrier penetration model,the suppression effect of ^(6,7)Li and ^(9)Be with a stable nucleus was systematically analyzed.In the cases of ^(6)Li and ^(7)Li,less suppression was predicted for relatively light-mass targets than for heavy-mass targets,and a notably distinct dependence relationship was identified,suggesting that the predominant breakup mechanisms might change in different mass target regions.In addition,minimum suppression factors were predicted to occur near target nuclei with neutron-closed shell.展开更多
Nuclear mass is an important property in both nuclear and astrophysics.In this study,we explore an improved mass model that incorporates a higher-order term of symmetry energy using algorithms.The sequential least squ...Nuclear mass is an important property in both nuclear and astrophysics.In this study,we explore an improved mass model that incorporates a higher-order term of symmetry energy using algorithms.The sequential least squares programming(SLSQP)algorithm augments the precision of this multinomial mass model by reducing the error from 1.863 MeV to 1.631 MeV.These algorithms were further examined using 200 sample mass formulae derived from theδE term of the E_(isospin) mass model.The SLSQP method exhibited superior performance compared to the other algorithms in terms of errors and convergence speed.This algorithm is advantageous for handling large-scale multiparameter optimization tasks in nuclear physics.展开更多
核子配对近似模型是研究原子核性质的重要方法之一,该方法已经在许多核领域内取得了重要成果。在对核129Sn的研究过程中,添加非集体对参数,并将该参数进行调整,从而观察非集体配对方式对核子能态的影响。经过计算后,发现非集体对主要对...核子配对近似模型是研究原子核性质的重要方法之一,该方法已经在许多核领域内取得了重要成果。在对核129Sn的研究过程中,添加非集体对参数,并将该参数进行调整,从而观察非集体配对方式对核子能态的影响。经过计算后,发现非集体对主要对负宇称能态有较大影响,而在正宇称能态中对角动量较高的能态有较大的影响。The nucleon pair approximation shell model is one of the most important methods for studying the properties of atomic nuclei, and the method has yielded important results in many nuclear fields. During the study of nuclear 129Sn, the non-collective pairing parameter is added and the parameter is tuned so as to observe the effect of the non-collective pairing approach on the energy states of nuclei. After calculations, it is found that the non-collective pairing has a large effect mainly on the negative-universal energy states, while in the positive-universal energy states it has a large effect on the energy states with higher angular momentum.展开更多
With the development of radioactive-ion-beam facilities,many exotic phenomena have been discovered or predicted in the nuclei far from the stability line,including cluster structure,shell structure,deformed halo,and s...With the development of radioactive-ion-beam facilities,many exotic phenomena have been discovered or predicted in the nuclei far from the stability line,including cluster structure,shell structure,deformed halo,and shape decoupling effects.The study of exotic nuclear phenomena is at the frontier of nuclear physics nowadays.The covariant density functional theory(CDFT)is one of the most successful microscopic models in describing the structure of nuclei in almost the whole nuclear chart.Within the framework of CDFT,toward a proper treatment of deformation and weak binding,the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc)has been developed.In this contribution,we review the applications and extensions of the DRHBc theory to the study of exotic nuclei.The DRHBc theory has been used to investigate the deformed halos in B,C,Ne,Na,and Mg isotopes and the theoretical descriptions are reasonably consistent with available data.A DRHBc Mass Table Collaboration has been founded,aiming at a high precision nuclear mass table with deformation and continuum effects included,which is underway.By implementing the angular momentum projection based on the DRHBc theory,the rotational excitations of deformed halos have been investigated and it is shown that the deformed halos and shape decoupling effects also exist in the low-lying rotational excitation states of deformed halo nuclei.展开更多
基金supported in part by the National Key R&D Program(Grant No.2023YFA1606900)the National Natural Science Foundation of China(Grant No.12235003)。
文摘Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particularly at the microscale.Here,we propose a novel method,vortex Mössbauer spectroscopy,for probing chiral structures.By leveraging the orbital angular momentum carried by vortex beams,this approach achieves high precision in detecting chiral structures at scales ranging from nanometers to hundreds of nanometers.Our simulation shows the ratio of characteristic lines in the Mössbauer spectra of ^(57)Fe under vortex beams exhibits differences of up to four orders of magnitude for atomic structures with different arrangements.Additionally,simulations reveal the response of ^(229m)Th chiral structures to vortex beams with opposite angular momenta differs by approximately 49-fold.These significant spectral variations indicate that this new vortex Mössbauer probe holds great potential for investigating the microscopic chiral structures and interactions of matter.
文摘本研究基于三个具有代表性的理论模型:相对论连续谱Hartree-Bogoliubov (RCHB)理论,相对论平均场(RMF)理论,Skyrme-Hartree-Fock-Bogoliubov (SHFB)模型,首先介绍了人工神经网络(ANN)方法,计算出了三个模型的单核子分离能的理论预测值。随后利用神经网络对单核子分离能的理论值进行了优化训练,降低了单核子分离能的理论预测值与实验值之间的均方根偏差(RMSD),并在此基础上进行了两种分区优化,分别为质子和中子的幻数分区,分区优化训练后进一步降低了RMSD。单核子分离能分区训练后的RMSD比整体直接训练的效果更好,特别能显著降低轻核区的RMSD,单中子分离能进行中子幻数分区训练的效果更好,单质子分离能进行质子幻数分区训练的效果更好。This research is based on three representative theoretical models: the Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, Relativistic Mean Field (RMF) theory, and Skyrme-Hartree-Fock-Bogoliubov (SHFB) model. First, the Artificial Neural Network (ANN) method was introduced to calculate theoretical predictions of single-nucleon separation energies for these three models. Subsequently, the neural network was employed to optimize and train the theoretical values of single-nucleon separation energies, reducing the root mean square deviation (RMSD) between theoretical predictions and experimental values. Two partitioning optimization schemes were then implemented: proton magic number partitioning and neutron magic number partitioning. The partitioned optimization training further reduced RMSD values. The partitioned training of single-nucleon separation energies demonstrated better performance than direct global training, particularly in significantly reducing RMSD in the light nuclei region. Specifically, neutron magic number partitioning showed superior effectiveness for optimizing single-neutron separation energies, while proton magic number partitioning yielded better results for single-proton separation energies.
基金the financial support of the Higher Education Commission Pakistan through project number 20-15394/NRPU/R&D/HEC/2021.
文摘Within the context of the proton-neutron quasi-particle random phase approximation(pn-QRPA)model and TALYS v1.96 code,the radiative capture(^(99)Tc(n,γ)^(100)Tc)and stellar weak interaction(^(99)Tc→^(99)Ru+e^(−)+ν_(e))rates were computed during thermal pulses operating in asymptotic giant branch stars.The Maxwellian average cross-section(MACS)and neutron capture rates for the^(99)Tc(n,γ)^(100)Tc process are analyzed within the context of statistical code TALYS v1.96.The effect of nuclear level density(NLD)andγ-strength functions on MACS and neutron capture rates has been examined.The model-based computations for MACS provided an insightful contrast to prior investigated findings.The sensitivity of stellar weak interaction rates to different densities and temperatures is investigated using the pn-QRPA model.The impact of thermally populated excited states on electron emission(β^(−))rates in^(99)Tc is extensively examined.Additionally,a comparison is made between the study of the stellarβ^(−)decay rates and the thermal neutron capture rates.It is found that at T_(9)=0.26 the thermal neutron capture rates(λ_((n,γ)))and the temperature dependent stellarβ^(−)decay rates( λ_(β-))cross each other.However,at higher temperatures,theλ(n,γ)are found to be higher than λ_(β-).
基金supported by the Joint Funds for the Innovation of Science and Technology,Fujian province(Nos.2021Y9190 and 2021Y9210)National Natural Science Foundation of China(No.12475121)National Key R&D Program of China(Nos.2023YFA1606503 and 2024YFE0109804).
文摘An improved formula considering the deformation effect for the α-decay half-lives is proposed based on WKB barrier penetrability.Using the quadrupole deformation values of the daughter nuclei obtained from the WS4 and FRDM models in the improved formula,the root mean square deviation(RMSD)between the calculated results and experimental data decreased from 0.456 to 0.413 and 0.415,respectively.Although the improved formula did not significantly reduce the overall RMSD,it produced results that better matched the experimental values for nuclei with larger deformations.Additionally,eXtreme Gradient Boosting(XGBoost)models were employed to further reduce the deviations between the calculated α-decay half-lives and experimental data,with the corresponding RMSDs decreasing from 0.413 to 0.295 and from 0.415 to 0.302,respectively.Furthermore,the improved empirical formula and XGBoost models were used to predict the α-decay half-lives of nuclei with Z=117,118,119,and 120.The results suggest that N=184 is the magic number.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB34020200)National Key Research and Development Program(MOST 2022YFA1602304)+1 种基金Scientific Research Instrument and Equipment Development Program of the Chinese Academy of Sciences(No.GJJSTD20210007)National Natural Science Foundation of China(Nos.12175156,U1632142).
文摘Highly oriented pyrolytic graphite (HOPG) is frequently adopted as the reaction target in12C+12C fusion reaction experiments owing to its superior purity.In this study,we investigate the reaction yield dependence on the accumulated beam dose on HOPG target using a novel detection system consisting of a time-projection chamber and silicon array.The reaction yields are significantly reduced under intense beam bombardment owing to radiation damage to the HOPG surface.The α_(0) and p_(0,1) yields decrease by 51.5% and 25%,respectively,when the ^(12)C^(2+) beam dose accumulates at 5 C.Using the novel detection system and HOPG target,the α0yield is determined to be 2.68_(-1.69)^(+4.69)×10^(-17/12) C after correcting for the yield loss due to radiation damage.Our result represents the highest sensitivity achieved to date in direct measurements of ^(12)C(12C,α_(0))^(20)Ne.
基金supported by National Natural Science Foundation of China(Nos.12105080 and 12375123)China Postdoctoral Science Foundation(No.2023M731015)Natural Science Foundation of Henan Province(No.242300422048).
文摘A machine learning approach based on Bayesian neural networks was developed to predict the complete fusion cross-sections of weakly bound nuclei.This method was trained and validated using 475 experimental data points from 39 reaction systems induced by ^(6,7)Li,^(9)Be,and ^(10)B.The constructed Bayesian neural network demonstrated a high degree of accuracy in evaluating complete fusion cross-sections.By comparing the predicted cross-sections with those obtained from a single-barrier penetration model,the suppression effect of ^(6,7)Li and ^(9)Be with a stable nucleus was systematically analyzed.In the cases of ^(6)Li and ^(7)Li,less suppression was predicted for relatively light-mass targets than for heavy-mass targets,and a notably distinct dependence relationship was identified,suggesting that the predominant breakup mechanisms might change in different mass target regions.In addition,minimum suppression factors were predicted to occur near target nuclei with neutron-closed shell.
基金supported by the National Natural Science Foundation of China(Nos.U2267205 and 12475124)a ZSTU intramural grant(22062267-Y)Excellent Graduate Thesis Cultivation Fund(LW-YP2024011).
文摘Nuclear mass is an important property in both nuclear and astrophysics.In this study,we explore an improved mass model that incorporates a higher-order term of symmetry energy using algorithms.The sequential least squares programming(SLSQP)algorithm augments the precision of this multinomial mass model by reducing the error from 1.863 MeV to 1.631 MeV.These algorithms were further examined using 200 sample mass formulae derived from theδE term of the E_(isospin) mass model.The SLSQP method exhibited superior performance compared to the other algorithms in terms of errors and convergence speed.This algorithm is advantageous for handling large-scale multiparameter optimization tasks in nuclear physics.
文摘核子配对近似模型是研究原子核性质的重要方法之一,该方法已经在许多核领域内取得了重要成果。在对核129Sn的研究过程中,添加非集体对参数,并将该参数进行调整,从而观察非集体配对方式对核子能态的影响。经过计算后,发现非集体对主要对负宇称能态有较大影响,而在正宇称能态中对角动量较高的能态有较大的影响。The nucleon pair approximation shell model is one of the most important methods for studying the properties of atomic nuclei, and the method has yielded important results in many nuclear fields. During the study of nuclear 129Sn, the non-collective pairing parameter is added and the parameter is tuned so as to observe the effect of the non-collective pairing approach on the energy states of nuclei. After calculations, it is found that the non-collective pairing has a large effect mainly on the negative-universal energy states, while in the positive-universal energy states it has a large effect on the energy states with higher angular momentum.
文摘With the development of radioactive-ion-beam facilities,many exotic phenomena have been discovered or predicted in the nuclei far from the stability line,including cluster structure,shell structure,deformed halo,and shape decoupling effects.The study of exotic nuclear phenomena is at the frontier of nuclear physics nowadays.The covariant density functional theory(CDFT)is one of the most successful microscopic models in describing the structure of nuclei in almost the whole nuclear chart.Within the framework of CDFT,toward a proper treatment of deformation and weak binding,the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc)has been developed.In this contribution,we review the applications and extensions of the DRHBc theory to the study of exotic nuclei.The DRHBc theory has been used to investigate the deformed halos in B,C,Ne,Na,and Mg isotopes and the theoretical descriptions are reasonably consistent with available data.A DRHBc Mass Table Collaboration has been founded,aiming at a high precision nuclear mass table with deformation and continuum effects included,which is underway.By implementing the angular momentum projection based on the DRHBc theory,the rotational excitations of deformed halos have been investigated and it is shown that the deformed halos and shape decoupling effects also exist in the low-lying rotational excitation states of deformed halo nuclei.
