Abstract Reference neutron fields in irradiation facilities are crucial for experimental research work in nuclear science and technology in general, and at the fundamental level for the measurement of neutron cross sections and validation of evaluated cross-section data. Monte Carlo particle transport techniques in conjunction with state-of-the-art nuclear data libraries are becoming the reference in the broad context of nuclear reactor analysis, and are extensively used for detailed computational characterization of irradiation facilities, including the calculation of neutron spectra. However, adjustment of the neutron spectra based on experimental data is still required. In this work we present the characterization of the neutron spectra in the three most important irradiation channels of the JSI TRIGA reactor with different spectral characteristics, as an important step in developing the experimental capabilities of the reactor for the purpose of nuclear data validation through activation dosimetry measurements. In the first part of this work we performed detailed Monte Carlo calculations of the neutron spectra, comparing the results obtained using different nuclear data libraries. In the main part of this work we employed the JSI developed GRUPINT spectrum adjustment code for the characterization of the neutron spectra, on the basis of the calculated neutron spectra and measured reaction rate ratios. A comprehensive overview of the methodology employed in the code and its abilities is given. We observe that a positive compensation of up to 10 % in the thermal part of the spectrum is needed, while no compensation is needed in the epithermal and fast parts. Absolute neutron flux levels were computed from the adjusted neutron spectra and absolute reaction rate measurements, and compared to the results of a previous analysis using only the Monte Carlo calculations. The work presented in this paper represents the basis for future experimental and analytical work, in particular extending the scope of the measured capture and threshold dosimetry nuclear reactions, to support a thorough characterization of the neutron spectra in the irradiation channels of the reactor. This effort will enable the JSI TRIGA reactor to support a broad scope of experiments for fundamental research as well as development or testing activities at the highest level.

中文翻译：

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使用 GRUPINT 谱调整代码表征 JSI TRIGA 反应堆三个辐照通道中的中子谱

摘要 辐照设施中的参考中子场对于一般核科学和技术的实验研究工作至关重要，并且在中子截面测量和评估截面数据验证的基础层面上是至关重要的。蒙特卡罗粒子传输技术与最先进的核数据库相结合，正在成为核反应堆分析广泛背景下的参考，并广泛用于辐照设施的详细计算表征，包括中子谱的计算。然而，仍然需要根据实验数据调整中子谱。在这项工作中，我们展示了具有不同光谱特性的 JSI TRIGA 反应堆三个最重要辐照通道中的中子光谱表征，作为开发反应堆实验能力的重要一步，以通过活化剂量学进行核数据验证测量。在这项工作的第一部分，我们对中子谱进行了详细的蒙特卡罗计算，比较了使用不同核数据库获得的结果。在这项工作的主要部分，我们使用 JSI 开发的 GRUPINT 谱调整代码来表征中子谱，基于计算的中子谱和测量的反应速率比。给出了代码中采用的方法及其能力的全面概述。我们观察到在光谱的热部分需要高达 10% 的正补偿，而在超热和快速部分不需要补偿。绝对中子通量水平是根据调整后的中子光谱和绝对反应速率测量值计算得出的，并与之前仅使用蒙特卡罗计算的分析结果进行比较。本文提出的工作代表了未来实验和分析工作的基础，特别是扩展了测量的俘获和阈值剂量学核反应的范围，以支持对反应堆辐照通道中的中子谱进行全面表征。