原子核质量是反映核结构与稳定性的重要物理量,在核结构研究与天体核物理过程中均具有关键作用.目前,基于神经网络的研究多集中于结合能或中子、质子分离能的单一预测,较少关注结合能与分离能之间的物理约束关系.本研究基于相对论平均...原子核质量是反映核结构与稳定性的重要物理量,在核结构研究与天体核物理过程中均具有关键作用.目前,基于神经网络的研究多集中于结合能或中子、质子分离能的单一预测,较少关注结合能与分离能之间的物理约束关系.本研究基于相对论平均场点耦合模型PCF-PK1,结合神经网络对原子核结合能以及单、双中子和单、双质子分离能进行了系统预测.在训练过程中引入分离能约束,以保持结合能与分离能之间的物理自洽性.结果表明,神经网络能够显著提升结合能的整体预测精度.其中,在特定损失函数权重组合下,结合能的预测均方根偏差可达到0.140 Me V.进一步分析发现,在保持物理自洽性的前提下,引入分离能约束能够同时对结合能和分离能的预测结果实现小幅优化.展开更多
评价核结构数据库(Evaluated Nuclear Structure Data File,ENSDF)作为核物理领域的核心数据资源,正面临数据量快速增长与传统格式僵化带来的挑战.本文旨在系统探讨ENSDF的现代化进程,深入分析其原始数据格式的历史局限性,并综述国际核...评价核结构数据库(Evaluated Nuclear Structure Data File,ENSDF)作为核物理领域的核心数据资源,正面临数据量快速增长与传统格式僵化带来的挑战.本文旨在系统探讨ENSDF的现代化进程,深入分析其原始数据格式的历史局限性,并综述国际核数据中心在数据结构现代化方面的主要努力.文中重点介绍了JSON、面向对象数据库及机器学习方法在核数据评价中的应用,以及NuDat网络接口如何借助现代可视化技术实现数据的高效交互与传播.此外,本文还介绍了中国核数据团队在该领域的自主探索与实践,特别是中山大学核数据团队在借鉴国际经验的基础上,建立了本地化的原子核数据可视化查询系统.基于这一框架,本文进一步结合JSON化的核结构与衰变数据,利用随机森林方法对超重核多种衰变模式的半衰期进行了系统建模与预测.结果表明,该模型在捕捉非线性关联、修正经验公式残差及识别主衰变模式方面具有显著优势,与实验数据的一致率达92.2%,预测与实验半衰期均方根误差平均降低超过50%.研究结果显示,现代化核结构数据库为人工智能在核物理领域的深入应用奠定了基础,为我国核科学研究提供了坚实的数据支撑,并体现了我国在核数据基础设施建设方面的自主创新能力.展开更多
To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produce...To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produced by the tandem-accelerator in the China Institute of Atomic Energy was utilized.The proton beam was first transmitted through a 60.5μm aluminum foil and then impinged on a natural LiF target to produce neutron beam via^(7)Li(p,n)7Be reaction.The quasi-Gaussian energy distribution of protons in the LiF target resulted in neutron energy spectra that agreed with a Maxwellian energy distribution at kT=(22±2)keV,which was achieved by integrating neutrons detected within an emission angle of 65.0°±2.6°using a ^(6)Li glass detector positioned at 65°relative to the proton beam direction.The narrow angular spread of the Maxwelliandistributed neutron beam enables direct measurement of neutron capture cross-sections for most s-process nuclides,overcoming previous experimental limitations associated with broad angular distributions.展开更多
We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-...We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-2(SHANS2),a gas-filled recoil separator located at the China Accelerator Facility for Superheavy Elements(CAFE2).In total,20 decay chains are attributed to ^(288)Mc and 1 decay chain is assigned to ^(287)Mc.The measured oa-decay properties of ^(287,288)Mc as well as its descendants are consistent with the known data.No additional decay chains originating from the 2n or 5n reaction channels were detected.The excitation function of the ^(243)Am(^(48)Ca,3n)^(288)Mc reaction was measured at the cross-section level of picobarn,which indicates the promising capability for the study of heavy and superheavy nuclei at the facility.展开更多
Fig.3.(a)α-particle energy spectra,and(b)decay-time distributions on a logarithmic scale for the observed 288Mc and its descendant nuclei.In the panel(a),the red histograms show the observed full-energy events,while ...Fig.3.(a)α-particle energy spectra,and(b)decay-time distributions on a logarithmic scale for the observed 288Mc and its descendant nuclei.In the panel(a),the red histograms show the observed full-energy events,while the corresponding blue histograms show the reconstructed events.The red smooth curves in panel(b)are the expected time distributions according to the corresponding half-lives extracted from this work.展开更多
文摘原子核质量是反映核结构与稳定性的重要物理量,在核结构研究与天体核物理过程中均具有关键作用.目前,基于神经网络的研究多集中于结合能或中子、质子分离能的单一预测,较少关注结合能与分离能之间的物理约束关系.本研究基于相对论平均场点耦合模型PCF-PK1,结合神经网络对原子核结合能以及单、双中子和单、双质子分离能进行了系统预测.在训练过程中引入分离能约束,以保持结合能与分离能之间的物理自洽性.结果表明,神经网络能够显著提升结合能的整体预测精度.其中,在特定损失函数权重组合下,结合能的预测均方根偏差可达到0.140 Me V.进一步分析发现,在保持物理自洽性的前提下,引入分离能约束能够同时对结合能和分离能的预测结果实现小幅优化.
文摘评价核结构数据库(Evaluated Nuclear Structure Data File,ENSDF)作为核物理领域的核心数据资源,正面临数据量快速增长与传统格式僵化带来的挑战.本文旨在系统探讨ENSDF的现代化进程,深入分析其原始数据格式的历史局限性,并综述国际核数据中心在数据结构现代化方面的主要努力.文中重点介绍了JSON、面向对象数据库及机器学习方法在核数据评价中的应用,以及NuDat网络接口如何借助现代可视化技术实现数据的高效交互与传播.此外,本文还介绍了中国核数据团队在该领域的自主探索与实践,特别是中山大学核数据团队在借鉴国际经验的基础上,建立了本地化的原子核数据可视化查询系统.基于这一框架,本文进一步结合JSON化的核结构与衰变数据,利用随机森林方法对超重核多种衰变模式的半衰期进行了系统建模与预测.结果表明,该模型在捕捉非线性关联、修正经验公式残差及识别主衰变模式方面具有显著优势,与实验数据的一致率达92.2%,预测与实验半衰期均方根误差平均降低超过50%.研究结果显示,现代化核结构数据库为人工智能在核物理领域的深入应用奠定了基础,为我国核科学研究提供了坚实的数据支撑,并体现了我国在核数据基础设施建设方面的自主创新能力.
基金National Natural Science Foundation of China(12125509,11961141003,12275361,U2267205,12175152,12175121)National Key Research and Development Project(2022YFA1602301)Continuous-support Basic Scientific Research Project。
文摘To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produced by the tandem-accelerator in the China Institute of Atomic Energy was utilized.The proton beam was first transmitted through a 60.5μm aluminum foil and then impinged on a natural LiF target to produce neutron beam via^(7)Li(p,n)7Be reaction.The quasi-Gaussian energy distribution of protons in the LiF target resulted in neutron energy spectra that agreed with a Maxwellian energy distribution at kT=(22±2)keV,which was achieved by integrating neutrons detected within an emission angle of 65.0°±2.6°using a ^(6)Li glass detector positioned at 65°relative to the proton beam direction.The narrow angular spread of the Maxwelliandistributed neutron beam enables direct measurement of neutron capture cross-sections for most s-process nuclides,overcoming previous experimental limitations associated with broad angular distributions.
文摘基于广义约化R矩阵理论,使用RAC程序(R-matrix analysis code)综合分析了^(6)He系统中所有可以利用的实验数据,给出了氚核入射10-2—20 MeV能量范围内主要反应道的评价核数据.其中积分截面包括T(t,2n)^(4)He,T(t,n)^(5)He,T(t,d)^(4)H;微分截面包括T(t,2n)^(4)He,T(t,n)^(5)He,T(t,d)^(4)H,T(t,t)T.结果表明,RAC的评价结果与实验数据和ENDF/B-Ⅷ.1的评价数据整体符合良好.重点关注T(t,2n)^(4)He反应,评价值在10^(-2)—20 MeV范围内与已有实验数据一致,在2.9 Me V附近出现由2+能级主导的共振,在1.9 Me V处,已有实验同时测量了积分截面和角分布,本工作的评价结果在两类数据上均表现出良好的一致性,积分截面与微分截面的联合约束有效提升了R矩阵参数的稳定性和评价结果的可靠性.基于6He系统的整体评价,进一步补充了T(t,n)^(5)He和T(t,d)^(4)H反应的截面数据.本工作完善了聚变反应相关的数据基础,并为后续与镜像系统6Be系统的联合分析奠定了基础.
基金supported in part by the National Key R&D Program of China (Contract Nos.2023YFA1606500,2024YFE0109800,and 2024YFE0110400)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB34010000)+5 种基金the Gansu Key Project of Science and Technology (Grant No.23ZDGA014)the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2021B0301030006)the National Natural Science Foundation of China (Grant Nos.12105328,W2412040,12475126,12422507,12035011,12375118,12435008,and W2412043)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-002)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant Nos.2020409 and 2023439)the Russian Science Foundation (Grant No.25-42-00003)。
文摘We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-2(SHANS2),a gas-filled recoil separator located at the China Accelerator Facility for Superheavy Elements(CAFE2).In total,20 decay chains are attributed to ^(288)Mc and 1 decay chain is assigned to ^(287)Mc.The measured oa-decay properties of ^(287,288)Mc as well as its descendants are consistent with the known data.No additional decay chains originating from the 2n or 5n reaction channels were detected.The excitation function of the ^(243)Am(^(48)Ca,3n)^(288)Mc reaction was measured at the cross-section level of picobarn,which indicates the promising capability for the study of heavy and superheavy nuclei at the facility.
文摘Fig.3.(a)α-particle energy spectra,and(b)decay-time distributions on a logarithmic scale for the observed 288Mc and its descendant nuclei.In the panel(a),the red histograms show the observed full-energy events,while the corresponding blue histograms show the reconstructed events.The red smooth curves in panel(b)are the expected time distributions according to the corresponding half-lives extracted from this work.
