How to produce accurate inelastic cross sections from an indirect measurement method
How to produce accurate inelastic cross sections from an indirect measurement method
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如何通过间接测量方法产生精确的非弹性横截面
DOI：
10.1051/epjn/2018020
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发表时间：
2018
影响因子：
0.5
通讯作者：
A. Plompen
中科院分区：
文献类型：
--
作者：
M. Kerveno;G. Henning;C. Borcea;P. Dessagne;M. Dupuis;S. Hilaire;A. Negret;M. Nyman;A. Olăcel;Eliot Party;A. Plompen
非弹性反应((n，xn)对于x ≥ 1)在反应堆堆芯中起着关键作用，因为它们影响着中子的减速。因此，反应堆的中子能谱取决于这个与弹性散射和裂变激烈竞争的过程；一个很好的例子是238U非弹性散射(x = 1)影响反应堆中的kff和径向功率分布。几年来，核数据库中非弹性截面的知识不足以准确地模拟反应堆堆芯，对新测量的强烈需求已经出现，对截面上的不确定性提出了非常严格的目标(只有几个百分点)。为了绕过众所周知的探测中子的实验困难，瞬发γ-射线能谱方法是获得非弹性截面的一种强大而间接的方法。我们的合作已经使用这种方法十多年了，已经产生了从7Li到238U的大量(n，n‘γ)核截面。在本文中，我们将首先讨论关于控制(n，n’γ)截面估计中涉及的所有不确定度的瞬发γ-射线谱问题。其次，我们将侧重于理论建模的作用，在某些情况下，理论建模对于实现(n，n‘)截面上几个百分点的不确定度目标至关重要。
Inelastic reactions ((n,xn) for x ≥ 1) play a key role in reactor cores as they influence the slowing down of the neutrons. A reactor neutron energy spectrum depends thus on this process which is in strong competition with elastic scattering and fission; a nice example is the case of 238 U. Inelastic scattering (x = 1) impacts k eff and radial power distribution in the nuclear reactor. For several years, it has been shown that the knowledge of the inelastic cross sections in nuclear databases is not good enough to accurately simulate reactor cores and a strong demand for new measurements has emerged with very tight objectives (only a few percent) for the uncertainties on the cross section. To bypass the well-known experimental difficulty to detect neutrons, the prompt γ -ray spectroscopy method is a powerful but indirect way to obtain inelastic cross sections. Our collaboration has used this method for more than ten years and have produced a lot of (n,n′γ ) cross sections for nuclei from 7 Li to 238 U. In this article, we will first discuss the issues of the prompt γ -ray spectroscopy regarding the control of all the uncertainties involved in the (n,n′γ ) cross section estimation. Secondly, we will focus on the role of theoretical modeling which, in certain cases, is crucial to reach the objectives of a few percent uncertainty on the (n,n′) cross sections.