Development of lower-energy neutron spectroscopy for areal density measurement in implosion experiment at NIF and OMEGA
Development of lower-energy neutron spectroscopy for areal density measurement in implosion experiment at NIF and OMEGA
复制标题
开发低能中子能谱，用于 NIF 和 OMEGA 内爆实验中的面密度测量
DOI：
10.1117/12.451266
复制
发表时间：
2001
期刊：
影响因子：
--
通讯作者：
T. Sangster
中科院分区：
文献类型：
--
作者：
N. Izumi;R. Lerche;T. Phillips;G. Schmid;M. Moran;T. Sangster
面密度((Sigma)R)是表征ICF内爆性能的一个基本参数。对于将在NIF和LMJ的内爆实验中实现的高面密度((Sigma)R>；0.1g/cm2)，靶面密度超过带电粒子的停止范围，用带电粒子能谱测量将是困难的。在这一地区，使用下移中子计数的面密度测量方法是一个很有前途的替代方法。中子在内爆等离子体中散射的几率与等离子体的面密度成正比。被特定靶核散射的中子谱具有低能截断的特点。这使得燃料和推进器(Sigma)R的测量能够分开、同时进行。要将这一概念应用于内爆实验，探测器应具有极大的动态范围。还需要为低能中子提供足够的信号输出。锂玻璃闪烁光纤板(LG-SCRIFI)是这种应用的一个很有前途的候选材料。本文提出了一种基于锂玻璃闪烁光纤板下移中子测量的新技术。报道了用蒙特卡罗方法进行仪器测量和本底估算的细节。
Areal density ((sigma) R) is a fundamental parameter that characterizes the performance of an ICF implosion. For high areal densities ((sigma) R>0.1 g/cm2), which will be realized in implosion experiments at NIF and LMJ, the target areal density exceeds the stopping range of charged particles and measurements with charged particle spectroscopy will be difficult. In this region, an areal density measurement method using down shifted neutron counting is a promising alternative. The probability of neutron scattering in the imploded plasma is proportional to the areal density of the plasma. The spectrum of neutrons scattered by the specific target nucleus has a characteristic low energy cut off. This enables separate, simultaneous measurements of fuel and pusher (sigma) Rs. To apply this concept in implosion experiments, the detector should have extremely large dynamic range. Sufficient signal output for low energy neutrons is also required. A lithium-glass scintillation-fiber plate (LG-SCIFI) is a promising candidate for this application. In this paper we propose a novel technique based on down shifted neutron measurements with a lithium-glass sctintillation-fiber plate. The details of instrumentation and background estimation with Monte Carlo calculation are reported.