Characterization of a Mixed Multiplicity Counter Based on Liquid Organic Scintillators
Characterization of a Mixed Multiplicity Counter Based on Liquid Organic Scintillators
复制标题
基于液体有机闪烁体的混合多重计数器的表征
DOI：
--
复制
发表时间：
2011
影响因子：
1.8
通讯作者：
S. Pozzi
中科院分区：
文献类型：
--
作者：
A. Enqvist;K. Weinfurther;M. Flaska;S. Pozzi
研制了一套能同时对中子和伽马射线进行多次测量的测量系统。这种方法的好处是增加了可观测到的数量。纯中子分析得出三阶倍数的三个可观测值，而中子/伽马射线组合分析得出同一阶倍数的九个可观测值。其想法是，在确定样品的未知参数时，如裂变质量，使用额外的可观测数据以实现更高的精度。该测量系统基于液体闪烁探测器(EJ-309S)，它将检测到的脉冲馈入数字数据采集系统。EJ-309具有出色的脉冲形状识别能力，可以准确区分伽马射线脉冲和中子脉冲。PSD对于正确识别直到三阶的不同倍数至关重要：n、γ、nn、nγ，γγ、nnn、nnγ、nγγ和γγγ。之前对测量系统的调查表明，对于252Cf这样的自发裂变源，可以在几分钟内获得良好的计数统计数据。在本文中，我们提出了新的测量结果和相应的蒙特卡罗模拟，旨在表征测量系统。详细讨论了测量倍数与模拟倍数的比较，发现两者有较好的一致性。
A measurement system capable of multiplicity measurements for both neutrons and gamma rays has been developed. The benefit of such an approach is in the increased number of available observables. A pure neutron assay results in three observables for third-order multiples, while a combined neutron/gamma-ray assay results in nine observables for the same order of multiples. The idea is to use the additional observables to achieve greater accuracy when determining unknown parameters of the sample such as the fissile mass. The measurement system is based on liquid scintillation detectors (EJ-309s) which feed detected pulses to a digital data-acquisition system. The excellent pulse shape discrimination capabilities of the EJ-309s allow for accurate differentiation between gamma-ray pulses and neutron pulses. The PSD is vital to correctly identify the different multiples up to the third order: n, γ , nn, nγ , γγ , nnn, nnγ , nγγ and γγγ . Previous investigation of the measurement system showed that good counting statistics can be achieved within minutes for spontaneous-fission sources such as 252Cf. In this paper, we present new measurement results and corresponding Monte Carlo simulations aimed at characterizing the measurement system. Comparison of the measured and simulated multiples is discussed in detail and a relatively good agreement is found.