平坦效率对于实现光中子反应的单中子、双中子和三中子事件的区分和截面的计算非常关键。介绍了一种用于逆康普顿散射γ源(Shanghai Laser Electron Gamma Source,SLEGS)光中子(γ,n)截面测量的4π平坦效率3He中子探测器阵列的设计与模...平坦效率对于实现光中子反应的单中子、双中子和三中子事件的区分和截面的计算非常关键。介绍了一种用于逆康普顿散射γ源(Shanghai Laser Electron Gamma Source,SLEGS)光中子(γ,n)截面测量的4π平坦效率3He中子探测器阵列的设计与模拟。采用Geant4程序对平坦效率3He探测器的优化布局和效率进行了模拟,针对设计的由20只Φ50 mm×500 mm 5 cm 3He正比计数管和6只Φ25 mm×500 mm 3He正比计数管组成的4π平坦效率中子探测器,模拟给出探测器平均效率曲线在1 keV^6 MeV的效率为34.4%~45.9%。模拟中以209Bi靶为例,靶尺寸为Φ20 mm×4 mm,通过对产生中子的角分布,能谱的模拟计算,发现中子出射角度在90°对称,探测器的4π布局能够完全覆盖入射到聚乙烯慢化体的中子,出射中子能量随着中子分离能呈现出规律的变化关系;随着γ能量增加,出射道开放增多,出射中子的能量总是分布在1 keV^4 MeV之间,探测器阵列在这一能区的平均效率为40%~46%。展开更多
介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEG...介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEGS光束线站在2021年12月通过工艺验收,2022年10月进入到试运行阶段,2023年9月对用户开放运行。SLEGS是国际上首台采用变换碰撞角度连续改变伽马束能量的光束线站,具有最好的能量扫描精度、流强密度以及高效的能量调节能力。试运行阶段SLEGS光束线站重点解决了伽马束能谱和流强的在线监测问题,主要完成了平坦效率谱仪(FED)测量光中子截面的实验方法学研究,以及开展了伽马成像、伽马活化、正电子产生等应用平台的拓展和研究。随着逆康普顿散射技术的发展和应用需求的增加,未来短脉冲、高极化、高通量以及小型化的激光康普顿散射光源将会迎来更好的发展机遇,将在核物理、天体物理、粒子物理、极化物理,以及航空航天、医学检测、能源开发等伽马源应用研究领域发挥重要的作用。展开更多
Silver indium cadmium(Ag–In–Cd) control rod is widely used in pressurized water reactor nuclear power plants,and it is continuously consumed in a high neutron flux environment. The mass ratio of ^(107)Ag in the Ag...Silver indium cadmium(Ag–In–Cd) control rod is widely used in pressurized water reactor nuclear power plants,and it is continuously consumed in a high neutron flux environment. The mass ratio of ^(107)Ag in the Ag–In–Cd control rod is 41.44%. To accurately calculate the consumption value of the control rod, a reliable neutron reaction cross section of the ^(107)Ag is required. Meanwhile,^(107)Ag is also an important weak r nucleus. Thus, the cross sections for neutron induced interactions with ^(107)Ag are very important both in nuclear energy and nuclear astrophysics. The(n, γ) cross section of ^(107)Ag has been measured in the energy range of 1–60 eV using a back streaming white neutron beam line at China spallation neutron source. The resonance parameters are extracted by an R-matrix code. All the cross section of ^(107)Ag and resonance parameters are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00010.展开更多
The^(74)Se is one of 35 p-nuclei,and^(82)Se is a r-process only nucleus,and their(n,γ)cross sections are vital input parameters for nuclear astrophysics reaction network calculations.The neutron capture cross section...The^(74)Se is one of 35 p-nuclei,and^(82)Se is a r-process only nucleus,and their(n,γ)cross sections are vital input parameters for nuclear astrophysics reaction network calculations.The neutron capture cross section in the resonance range of isotopes and even natural selenium samples has not been measured.Promptγ-rays originating from neutron-induced capture events were detected by four C_(6)D_(6) liquid scintillator detectors at the Back-n facility of China Spallation Neutron Source(CSNS).The pulse height weighting technique(PHWT)was used to analyze the data in the 1 e V to 100 ke V region.The deduced neutron capture cross section was compared with ENDF/B-VIII.0,JEFF-3.2,and JENDL-4.0,and some differences were found.Resonance parameters were extracted by the R-matrix code SAMMY in the 1 e V-1 ke V region.All the cross sections ofnatSe and resonance parameters are given in the datasets.The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00019.展开更多
The astrophysical reaction rate of 12C（α,γ）16O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at T9=0.2. The existing re...The astrophysical reaction rate of 12C（α,γ）16O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at T9=0.2. The existing results even disagree with each other to a certain extent. In this paper, the El, E2 and total （E1＋E2） 12C（α,γ）16O reaction rates are calculated in the temperature range from T9=0.3 to 2 according to all the available cross section data. A new analytic expression of the 12C（α,γ）16O reaction rate is brought forward based on the reaction mechanism. In this expression, each part embodies the underlying physics of the reaction. Unlike previous works, some physical parameters are chosen from experimental results directly, instead of all the parameters obtained from fitting. These parameters in the new expression, with their 3σ fit errors, are obtained from fit to our calculated reaction rate from T9=0.3 to 2. Using the fit results, the analytic expression of 12C（α,γ）16Oreaction rate is extrapolated down to T9=0.05 based on the underlying physics. The 12C（α,γ）16O reaction rate at T9=0.2 is （8.78 ± 1.52） × 10^15 cm3s^-1mol^-1. Some comparisons and discussions about our new 12C（α,γ）16Oreaction rate are presented, and the contributions of the reaction rate correspond to the different part of reaction mechanism are given. The agreements of the reaction rate below T9=2 between our results and previous works indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. Furthermore, we believe our method to investigate the 12C（α,γ）16O reaction rate is reasonable, and this method can also be employed to study the reaction rate of other astrophysical reactions. Finally, a new constraint of the supernovae production factor of some isotopes are illustrated according to our 12C（α,γ）16O reaction rates.展开更多
The ambiguity of the structure of ^(12)Be especially in the configuration of Be ground state has attracted a lot of attention recently.We notice that the nuclear reaction cross section or at low energy region is sensi...The ambiguity of the structure of ^(12)Be especially in the configuration of Be ground state has attracted a lot of attention recently.We notice that the nuclear reaction cross section or at low energy region is sensitive to the surface structure of ^(12)Be,which is greatly impacted by the ground state configuration of ^(12)Be especially by the occupancy probability of the s orbital component.By using existed interaction cross section data of ^(12)Be on C at 790 MeV/nucleon and Glauber model,the upper limit of the s orbital occupation probability of ^(12)Be ground state is roughly determined to be about 56%with Single Particle Model calculations.This demonstrates that the method is very promising to determine the s orbital component of ^(12)Be with proper nuclear-matter density distribution calculations for different orbitals of ^(12)Be ground state.Hence we bring forward to determine the s orbital component of ^(12)Be by measuring the ctr of ^(12)Be on C and Al at several tens of MeV/nucleon.In this paper,the feasibility and detailed experimental scheme of the ctr measurement are carefully studied.The precision of the s orbital occupation probability of ^(12)Be ground state is expected to achieve 9%by using the proposed 2%ctr data.展开更多
The differential cross sections for elastic scattering products of ^17F on ^208Pb have been measured. The angular dispersion plots of ln（dσ/dθ） versus θ^2 are obtained from the angular distribution of the elastic...The differential cross sections for elastic scattering products of ^17F on ^208Pb have been measured. The angular dispersion plots of ln（dσ/dθ） versus θ^2 are obtained from the angular distribution of the elastic scattering differential cross sections. Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle. This turning angle can be clarified as nucleal rainbow in classical deflection function. The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena.展开更多
恒星氦燃烧阶段3α反应和^(12)C(α,γ)^(16)O反应相互竞争,两者的反应率共同决定了氦燃烧结束后^(12)C与^(16)O的丰度比,该比值是大质量恒星后继演化以及伴随的元素核合成过程的初始条件。目前,氦燃烧^(12)C(α,γ)^(16)O反应起始T_9=...恒星氦燃烧阶段3α反应和^(12)C(α,γ)^(16)O反应相互竞争,两者的反应率共同决定了氦燃烧结束后^(12)C与^(16)O的丰度比,该比值是大质量恒星后继演化以及伴随的元素核合成过程的初始条件。目前,氦燃烧^(12)C(α,γ)^(16)O反应起始T_9=0.2处,天体物理模型要求的反应率的精确度要低于10%,然而尚未有实验或理论给出满足要求的结果。最为直接和可靠地获取^(12)C(α,γ)^(16)O反应率的方法,就是尽可能往低能区测量其天体物理S因子,然后通过理论外推到感兴趣的能区。为此基于经典的R-矩阵理论,建立了适用于低能核反应的多道、多能级的约化R-矩阵理论来拟合几乎所有可用的^(16)O系统的实验数据。配合使用协方差统计和误差传播理论,拟合外推得到了客观的、内部自恰的和唯一性好的^(12)C(α,γ)^(16)O反应天体物理S因子。总的外推S因子STOT(0.3 Me V)=162.7±7.3 keV·b,理论上首次给出达到恒星演化与元素核合成模型的最低要求的S因子。基于计算给出的全能区的S因子,数值积分给出了温度位于0.04≤T_9≤10的^(12)C(α,γ)^(16)O天体物理反应率。在T_9=0.2处,推荐的反应率为(7.83±0.35)×10^(-15)cm^3mol^(-1)s^(-1)。展开更多
文摘平坦效率对于实现光中子反应的单中子、双中子和三中子事件的区分和截面的计算非常关键。介绍了一种用于逆康普顿散射γ源(Shanghai Laser Electron Gamma Source,SLEGS)光中子(γ,n)截面测量的4π平坦效率3He中子探测器阵列的设计与模拟。采用Geant4程序对平坦效率3He探测器的优化布局和效率进行了模拟,针对设计的由20只Φ50 mm×500 mm 5 cm 3He正比计数管和6只Φ25 mm×500 mm 3He正比计数管组成的4π平坦效率中子探测器,模拟给出探测器平均效率曲线在1 keV^6 MeV的效率为34.4%~45.9%。模拟中以209Bi靶为例,靶尺寸为Φ20 mm×4 mm,通过对产生中子的角分布,能谱的模拟计算,发现中子出射角度在90°对称,探测器的4π布局能够完全覆盖入射到聚乙烯慢化体的中子,出射中子能量随着中子分离能呈现出规律的变化关系;随着γ能量增加,出射道开放增多,出射中子的能量总是分布在1 keV^4 MeV之间,探测器阵列在这一能区的平均效率为40%~46%。
文摘介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEGS光束线站在2021年12月通过工艺验收,2022年10月进入到试运行阶段,2023年9月对用户开放运行。SLEGS是国际上首台采用变换碰撞角度连续改变伽马束能量的光束线站,具有最好的能量扫描精度、流强密度以及高效的能量调节能力。试运行阶段SLEGS光束线站重点解决了伽马束能谱和流强的在线监测问题,主要完成了平坦效率谱仪(FED)测量光中子截面的实验方法学研究,以及开展了伽马成像、伽马活化、正电子产生等应用平台的拓展和研究。随着逆康普顿散射技术的发展和应用需求的增加,未来短脉冲、高极化、高通量以及小型化的激光康普顿散射光源将会迎来更好的发展机遇,将在核物理、天体物理、粒子物理、极化物理,以及航空航天、医学检测、能源开发等伽马源应用研究领域发挥重要的作用。
基金supported by the National Natural Science Foundation of China (Grant Nos. 11875311, 11905274, 1705156, U2032146, 11865010, 11765015, and 1160509)the Natural Science Foundation of Inner Mongolia, China (Grant Nos. 2019JQ01 and 2018MS01009)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB34030000)。
文摘Silver indium cadmium(Ag–In–Cd) control rod is widely used in pressurized water reactor nuclear power plants,and it is continuously consumed in a high neutron flux environment. The mass ratio of ^(107)Ag in the Ag–In–Cd control rod is 41.44%. To accurately calculate the consumption value of the control rod, a reliable neutron reaction cross section of the ^(107)Ag is required. Meanwhile,^(107)Ag is also an important weak r nucleus. Thus, the cross sections for neutron induced interactions with ^(107)Ag are very important both in nuclear energy and nuclear astrophysics. The(n, γ) cross section of ^(107)Ag has been measured in the energy range of 1–60 eV using a back streaming white neutron beam line at China spallation neutron source. The resonance parameters are extracted by an R-matrix code. All the cross section of ^(107)Ag and resonance parameters are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00010.
基金supported by the National Natural Science Foundation of China(Grant Nos.11875311,11905274,11705156,11605097,and U2032146)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB34030000)。
文摘The^(74)Se is one of 35 p-nuclei,and^(82)Se is a r-process only nucleus,and their(n,γ)cross sections are vital input parameters for nuclear astrophysics reaction network calculations.The neutron capture cross section in the resonance range of isotopes and even natural selenium samples has not been measured.Promptγ-rays originating from neutron-induced capture events were detected by four C_(6)D_(6) liquid scintillator detectors at the Back-n facility of China Spallation Neutron Source(CSNS).The pulse height weighting technique(PHWT)was used to analyze the data in the 1 e V to 100 ke V region.The deduced neutron capture cross section was compared with ENDF/B-VIII.0,JEFF-3.2,and JENDL-4.0,and some differences were found.Resonance parameters were extracted by the R-matrix code SAMMY in the 1 e V-1 ke V region.All the cross sections ofnatSe and resonance parameters are given in the datasets.The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00019.
基金Project supported partially by the Innovation Program of Science and Technology of the Chinese Academy of Sciences (Grant Nos KJCX2.SW.N13 and KJCX3.SYW.N2)the National Natural Science Foundation of China (Grant Nos 10775167, 10675156 and 10610285)+2 种基金the Major State Basic Research Development Program (Grant No 2007CB815004)the Hundred Talent Project of the Chinese Academy of Sciences (Grant No 26010701)the Shanghai Development Foundation for Science and Technology (Grant No 06JC14082)
文摘The astrophysical reaction rate of 12C（α,γ）16O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at T9=0.2. The existing results even disagree with each other to a certain extent. In this paper, the El, E2 and total （E1＋E2） 12C（α,γ）16O reaction rates are calculated in the temperature range from T9=0.3 to 2 according to all the available cross section data. A new analytic expression of the 12C（α,γ）16O reaction rate is brought forward based on the reaction mechanism. In this expression, each part embodies the underlying physics of the reaction. Unlike previous works, some physical parameters are chosen from experimental results directly, instead of all the parameters obtained from fitting. These parameters in the new expression, with their 3σ fit errors, are obtained from fit to our calculated reaction rate from T9=0.3 to 2. Using the fit results, the analytic expression of 12C（α,γ）16Oreaction rate is extrapolated down to T9=0.05 based on the underlying physics. The 12C（α,γ）16O reaction rate at T9=0.2 is （8.78 ± 1.52） × 10^15 cm3s^-1mol^-1. Some comparisons and discussions about our new 12C（α,γ）16Oreaction rate are presented, and the contributions of the reaction rate correspond to the different part of reaction mechanism are given. The agreements of the reaction rate below T9=2 between our results and previous works indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. Furthermore, we believe our method to investigate the 12C（α,γ）16O reaction rate is reasonable, and this method can also be employed to study the reaction rate of other astrophysical reactions. Finally, a new constraint of the supernovae production factor of some isotopes are illustrated according to our 12C（α,γ）16O reaction rates.
基金Supported by the National Natural Science Foundation of China(No.11179018 and 11305238)the Instrument Developing Project of the Chinese Academy of Sciences(No.YZ201246)
文摘The ambiguity of the structure of ^(12)Be especially in the configuration of Be ground state has attracted a lot of attention recently.We notice that the nuclear reaction cross section or at low energy region is sensitive to the surface structure of ^(12)Be,which is greatly impacted by the ground state configuration of ^(12)Be especially by the occupancy probability of the s orbital component.By using existed interaction cross section data of ^(12)Be on C at 790 MeV/nucleon and Glauber model,the upper limit of the s orbital occupation probability of ^(12)Be ground state is roughly determined to be about 56%with Single Particle Model calculations.This demonstrates that the method is very promising to determine the s orbital component of ^(12)Be with proper nuclear-matter density distribution calculations for different orbitals of ^(12)Be ground state.Hence we bring forward to determine the s orbital component of ^(12)Be by measuring the ctr of ^(12)Be on C and Al at several tens of MeV/nucleon.In this paper,the feasibility and detailed experimental scheme of the ctr measurement are carefully studied.The precision of the s orbital occupation probability of ^(12)Be ground state is expected to achieve 9%by using the proposed 2%ctr data.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10675149 and 10535010, the Chinese Academy of Sciences under Grant No KJCX3.SYW.N1, and the National Basic Research Programme of China under Grant No 2007CB81500. We thank Wang Shunjin for his suggestion and fruitful discussion.
文摘The differential cross sections for elastic scattering products of ^17F on ^208Pb have been measured. The angular dispersion plots of ln（dσ/dθ） versus θ^2 are obtained from the angular distribution of the elastic scattering differential cross sections. Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle. This turning angle can be clarified as nucleal rainbow in classical deflection function. The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena.
文摘恒星氦燃烧阶段3α反应和^(12)C(α,γ)^(16)O反应相互竞争,两者的反应率共同决定了氦燃烧结束后^(12)C与^(16)O的丰度比,该比值是大质量恒星后继演化以及伴随的元素核合成过程的初始条件。目前,氦燃烧^(12)C(α,γ)^(16)O反应起始T_9=0.2处,天体物理模型要求的反应率的精确度要低于10%,然而尚未有实验或理论给出满足要求的结果。最为直接和可靠地获取^(12)C(α,γ)^(16)O反应率的方法,就是尽可能往低能区测量其天体物理S因子,然后通过理论外推到感兴趣的能区。为此基于经典的R-矩阵理论,建立了适用于低能核反应的多道、多能级的约化R-矩阵理论来拟合几乎所有可用的^(16)O系统的实验数据。配合使用协方差统计和误差传播理论,拟合外推得到了客观的、内部自恰的和唯一性好的^(12)C(α,γ)^(16)O反应天体物理S因子。总的外推S因子STOT(0.3 Me V)=162.7±7.3 keV·b,理论上首次给出达到恒星演化与元素核合成模型的最低要求的S因子。基于计算给出的全能区的S因子,数值积分给出了温度位于0.04≤T_9≤10的^(12)C(α,γ)^(16)O天体物理反应率。在T_9=0.2处,推荐的反应率为(7.83±0.35)×10^(-15)cm^3mol^(-1)s^(-1)。
