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中国物理学会期刊

14.1 MeV中子诱发92Mo(n,p)92mNb反应截面的精确测量

CSTR: 32037.14.aps.74.20250700

Accurate measurement of cross section of 92Mo(n,p)92mNb reaction induced by 14.1-MeV neutrons

CSTR: 32037.14.aps.74.20250700
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  • 钼作为重要的结构材料, 在核能系统中得到广泛应用, 因此钼高精度的中子反应截面对核能系统研发具有重要意义. 本文采用活化法和相对测量法测量了92Mo(n,p)92mNb的反应截面, 利用中国原子能科学研究院纳秒脉冲中子发生器(CPNG)对样品进行辐照、利用高纯锗探测器对辐照后样品进行活化产物核的活度测量, 并计算反应截面和修正因子, 最终得到14.1 MeV能点的92Mo(n,p)92mNb的反应截面. 为降低实验测量的不确定度, 本工作提出了待测产物与监测产物为同一个产物核的策略, 有效消除了产物核半衰期与衰变分支比、伽马探测效率、辐照过程的束流波动等引进的不确定度, 有效提高了测量精度, 获得了到目前为止精度最高的实验数据. 测量结果与其他实验数据进行了比较与分析, 本工作为该反应道的核数据评价提供了高精度的实验数据支撑.

     

    Molybdenum, as an important structural material, has been widely used in nuclear energy systems. Therefore, the high-precision neutron reaction cross-section of molybdenum is of great significance for developing nuclear energy systems. This paper uses activation and relative measurement methods to measure the reaction cross section of 92Mo(n,p)92mNb. The sample is irradiated at a 90º angle using nanosecond pulse neutron generator (CPNG) from the China Institute of Atomic Energy. After a period of cooling time, the activities of the activated product nuclei of the irradiated sample are measured using a high-purity germanium detector, and the reaction cross section and correction factors are calculated. The traditional correction factors include neutron fluence fluctuation, cascade, self-absorption, geometry and scattered-neutron corrections. Finally, the reaction cross section of 92Mo(n,p)92mNb at 14.1-MeV energy point is obtained. In order to reduce the uncertainty of experimental measurements, this work proposes a strategy in which the test product and the monitoring product are the same nuclide, effectively eliminating the uncertainties caused by the half-life and decay branch ratio of the product nucleus, gamma detection efficiency, and beam fluctuations during irradiation. This method significantly enhances the measurement accuracy, achieving the highest precision experimental data to date. This experiment aims to minimize the overall measurement uncertainty, so the stringent requirements are imposed on both the sample mass-thickness and the operating environment. The mass and thickness of each sample are therefore determined through five independent measurements using a 0.1 mg-precision analytical balance and a vernier caliper, respectively, and the mean values are taken. After the experiment, the measured data are carefully compared and analyzed with other datasets, The value of cross-section is not significantly different from others in the database and is located within the error range, which further verifies the feasibility of this method, providing high-precision experimental support for evaluating the nuclear-data of this reaction channel.

     

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