共查询到17条相似文献,搜索用时 46 毫秒
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不稳定核中子俘获截面对于恒星核合成及恒星内部中子密度研究有重要意义,但由于难以制靶,直接测量极其困难。在前期工作验证了替代比率法可以可靠推导不稳定核的中子俘获截面的基础上,本工作主要讨论了复合核自旋宇称态分布差异对复合核γ衰变概率比的影响。本工作计算了不同自旋宇称态下94Zr*和92Zr*衰变到γ道的衰变概率比,计算结果显示在中子入射能较高的区域复合核自旋宇称态分布差异对γ衰变概率比影响较小。同时,理论计算结果与实验数据比较显示,在低能区域(18O, 16O)的替代反应生成的复合核倾向布居与中子俘获反应生成的复合核相近的低自旋宇称态。本工作的计算和讨论进一步证明了替代比率法推导(n, γ)截面的可靠性。 相似文献
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s过程中的放射性核素中子俘获截面对天体核合成和核素丰度有重大影响, 在直接测量异常困难的情况下, 替代比率法是获得放射性核素中子俘获截面数据的一种间接新方法。 简单介绍了替代比率法理论, 并简要论述了用替代比率法推导中重核区放射性核素中子俘获截面的可行性。 The radioactive nuclei neutron capture cross section is very important to nuclearsynthesis and nuclide abundance in s process, but it is difficult to be measured directly because of the target production. A new method, surrogate ratio method which is developed from surrogate method, could be used to determine the cross section of radioactive nuclei neutron capture. In this paper, the surrogate ratio method was introduced and the feasibility was discussed to deduce the desired neutron capture cross sections with surrogate ratio method. 相似文献
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对于某些中子反应截面,在直接测量上存在困难。为了获得那些对核能发展极其重要的核数据,人们提出替代反应法,即利用带电粒子代替中子进行反应,从而实现中子反应截面间接测量的方法。现有替代反应一般采用非弹激发、转移等周边反应,涉及的角动量远比中子反应的大,需要理论修正,这造成了一定的困难。有鉴于此,提出利用轻带电离子的俘获反应作为替代反应,其复合核自旋与中子反应的相当,有效避免了自旋修正的困难。根据这个思路,采用236U的(α,f)和(α,2n)反应作为替代反应,成功提取了239Pu的(n,f)和(n,2n)反应截面,与ENDFB7评价库数据在误差范围内符合较好,表明了替代反应法的优越性,可以在核数据测量中推广应用。There are always difficulties in the direct measurement of reactions induced by neutron, in order to obtain the neutron induced nuclear reaction data which are extremely important for nuclear power development, the surrogate reaction method, which uses charged particles instead of neutron, was proposed. The existing surrogate reaction method generally chooses peripheral reaction as the surrogate reaction, such as inelastic scattering excitation or transfer reaction. As a result, the angular momentum involved is always far larger than the neutron induced reaction, which causes difficulties in the theoretical calculation. Because of this, we proposed to use light-ion capture reaction as the surrogate reaction, the compound nuclei spin is similar with that of the neutron induced reaction, so that the difficulties in spin correction can be effectively avoided. Based on this idea, the 239Pu(n, f) and (n, 2n) reaction cross sections were successfully extracted using 236U(α,f) and (α,2n) reactions as the surrogate reaction. The results coincide well with the data of ENDFB7 within the error range, which shows that the surrogate reaction method has its own superiority, and it can be applied in the measurement of nuclear data. 相似文献
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14MeV中子(n,T)与(n,3He)反应截面的系统学研究 总被引:1,自引:0,他引:1
本文研究14MeV中子(n,T)和(n,3He)反应截面的系统学特性。在考虑奇偶效应的基础上,给出了截面的系统学公式,σu,q=(A1/3+1)2aexp[β(N-Z+δ)/A]。用最小二乘法拟合得到奇偶核的经验参数对(n,T)反应,α,β分别为327.602,9.592和-24.495,-14.038。对(n,3He)反应,α,β分别为0.918和-11.340。利用这套参数计算的截面与实验值符合较好。此外,文中还讨论了反应的Ω值效应以及可能的反应机制。关键词: 相似文献
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在(p,γ)-(γ,p)平衡近似下,本文建立了简化的快质子俘获(rp)过程模型, 讨论了天体物理条件输入量 (即质子辐照时间、质子数密度及温度) 对rp过程的影响. 结合中国科学院近代物理研究所等时性质谱仪 (IMS) 上的最新实验数据, 本文进而分析了新测的缺中子原子核质量对rp过程的影响; 发现利用新测的41Ti质量, A=41处的丰度相较之前的计算结果增大了两个数量级, 而计算的相对丰度误差减小了近两个量级.关键词:快质子俘获过程γ)-(γ,p)平衡')\" href=\"#\">(p,γ)-(γ,p)平衡原子核质量缺中子原子核 相似文献
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开展了钍样品装置内钍核参数的积分中子学基础研究.参考混合堆概念设计搭建了内部放置了钍样品的一维贫铀/聚乙烯交替系统装置,采用加速器D-T中子源模拟聚变堆芯,利用前期开发的离线伽马测量方法测定了不同位置、不同中子谱情况下的232Th(n,γ)反应率,不确定度约为5%.结果显示,聚乙烯对14.1 MeV中子的慢化作用可有效提升钍俘获率,且贫铀对钍俘获率也有显著提升作用.实验结果与主流核数据库计算结果的对比显示,ENDF/B-VI.6和JENDL-3.3数据库的计算值比实验值平均约大6%,而较新的ENDF/B-VII.0数据库的计算值比实验值平均约大4%.因此,相比于之前数据库的钍核数据,ENDF/B-VII.0的计算值与实验结果匹配得较好,可作为相关概念设计的推荐核数据库. 相似文献
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在中国原子能科学研究院重水研究堆上用活化法对反应堆中子引起的181Hf (n,γ)182Hf反应截面进行了测量. 反应堆中样品照射位置的热中子与超热中子的通量比值约为10. 照射后样品中的182Hf/180Hf和 181Hf/180Hf的原子数比值是用热电离质谱测量的. 本工作以180Hf (n,γ)181Hf反应截面(14.80±0.60 b)为标准,测得的反应堆中子引起的181Hf (n,γ)182Hf反应截面值为80.0±5.6 b. 相似文献
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We have derived a formula for the neutron radiative capture cross section in the framework of a statistical model approach to nuclear reactions. Based on this formula, new systematics are established between the (n, γ) reaction cross section and the energy level density of a compound nucleus or a relative neutron excess of an even-even target nucleus for neutron incident energy above the resonance region to MeV. Good agreement with experimental data suggests that this new systematical law is helpful to analyze the experimental data. 相似文献
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提出了中子反应同质异能态截面比的半经验公式.该公式含有一系统学参数,适应于产物核质量数44≤A≤197、同质异能态自旋0≤Jm≤12和基态自旋0.5≤Jg≤8的中子反应.在入射中子能量En<20MeV能区,对该系统学参数进行了系统学研究.通过获得的半经验公式和系统学参数,可以很好地再现已有实验数据,也可较好地预言无实验数据的同质异能态截面比或同质异能态截面. 相似文献
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Rebecca Pachuau A. Gandhi Namrata Singh A. Kumar Mayur Mehta S. V. Suryanarayana L. S. Danu B. K. Nayak B. Lalremruata 《中国物理C(英文版)》2023,47(7):074001-074001-9
The cross section values of the begin{document}$ ^{71} $end{document} ![]()
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Ga(begin{document}$n, gamma $end{document} ![]()
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Ga reaction are measured, which are begin{document}$9.14 pm 0.81$end{document} ![]()
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mb and begin{document}$5.74 pm 0.50$end{document} ![]()
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mb at 2.15 and 3.19 MeV, respectively. The detailed uncertainty propagation and covariance analysis are also given. The begin{document}$ ^{7} $end{document} ![]()
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Li(begin{document}$p,n$end{document} ![]()
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Be reaction was used to generate the neutrons, and the neutron flux was normalized using the begin{document}$ ^{115} $end{document} ![]()
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In(begin{document}$n,n'$end{document} ![]()
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)begin{document}$ ^{115} $end{document} ![]()
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Inbegin{document}$ ^{m} $end{document} ![]()
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monitor reaction. The measured cross section data are compared with the data available in the EXFOR database, the data obtained using nuclear reaction model codes EMPIRE-3.2 and TALYS-1.95, and also the evaluated nuclear data from ENDF/B-VIII.0 and JEFF-3.1/A. The comparison shows that our result at 3.19 MeV is in good agreement with those of EMPIRE-3.2 and JEFF-3.1/A. Since there are no other measurements available at 3.19 MeV, our data could not be compared with literature data at 3.19 MeV, but they are consistent with the cross section values available at begin{document}$2.98 pm 0.26$end{document} ![]()
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and begin{document}$3.0 pm 0.1 $end{document} ![]()
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MeV. Our result at 2.15 MeV is slightly higher than the literature value available in EXFOR, evaluated value, and theoretically predicted result. 相似文献
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Close-coupling calculations are carried out for cross sections of the single electron capture in collisions of Nq+ (q = 5, 6, 7) ions with helium atoms in the collision velocity range from 0.3 a.u. to 1.8 a.u. The relative importances of the single ionization (SI) to the single capture (SC) are investigated for the Nq+ (q = 5, 6, 7) projectiles, respectively. The SI/SC cross section ratio for the N7+ projectile obtained from our calculations is in excellent agreement with the experimental data. The ratio curves also show us distinct behaviours when the charge of the projectile is different. The partial electron capture cross sections for different projectiles indicate that the electron on the target He atom tends to be captured by the projectile into its lower orbital of the outer shell with the decreasing projectile charge. 相似文献
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利用BaF2晶体对γ射线探测效率高、时间分辨率好的特点,研制了国内首套由40个BaF2探测器单元组成的γ全吸收型探测装置,用于在线测量中子俘获反应截面。在HI-13串列加速器上建立250~850 keV的中子源,其0°角的源强约为5.09×106 n/(Sr·s),使用γ全吸收型探测装置,通过瞬发γ射线法测量了93Nb、197Au、natC和空样品的实验数据。根据BaF2探测器信号的特征,采用了基线补偿、软件阈值设置、时间窗限定、脉冲幅度积分增长率设置和快慢成分比设置等多种数字化波形分析方法,剔除噪声信号以提高效应本底比。以197Au样品数据为标准,natC样品数据为样品相关性本底,空样品数据为样品无关性本底,采用相对测量法得到了93Nb的中子俘获反应截面实验数据。通过与ENDF评价库数据的比较,验证了测量装置和技术方法的可行性。 相似文献
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用活化法以93Nb(n,2n)92mNb和27Al(n,a)24Na反应截面为中子注量标准,对198Pt(n,2n)197m+gPt,198Pt(n, 2n)197mPt, 192Pt(n,2n)191Pt,194Pt(n,p)194Ir,195Pt(n,p)195mIr和 196Pt(n,p)196mIr反应截面进行了测量,由(13.5±0.2),(14.1±0.1)和(14.6±0.2)MeV中子引起的198Pt(n,2n)197m+gPt反应截面分别为(2038±159),(1919±73)和(1836±68)mb,198Pt(n,2n)197mPt反应截面为(974±37),(1055±39)和(1042±39)mb;由(14.1±0.1),(14.4±0.2)和(14.6±0.2)MeV中子引起的192Pt(n,2n)191Pt反应截面为(1680±103),(1810±67)和(2047±97)mb;由(14.1±0.1) 和(14.4±0.2)MeV中子引起的194Pt(n,p)194Ir反应截面为(3.8±0.4)和(5.4±0.5)mb;由(14.1±0.1),(14.4±0.2)MeV和(14.6±0.2)MeV中子引起的195Pt(n,p)195mIr反应截面为(1.0±0.2),(1.6±0.2)和(1.8±0.2)mb;由(13.5±0.2)和(14.4±0.2)MeV中子引起的196Pt(n,p)196mIr反应截面分别为(1.13±0.07)和(1.18±0.06)mb. 本工作的数据和其他一些作者的数据进行了比较. 相似文献
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We have suggested a new parameterization scheme for determining the reaction cross section at intermediate beam energies which reproduces the experimental data very well over a wide range of targets and projectiles both normal as well as exotic. In the present scheme the asymmetry aspect of large neutron/proton number has also been properly incorporated. 相似文献