Experimental Study on Nuclear Data Measurements of Actinide Nuclides in the Resonance Neutron Energy Region

本文综述了锕系核素Am-243、Pa-231、Th-229、Th-230和Np-237的核数据现状。利用京都大学铅减速谱仪（KULS）与京都大学反应堆研究所（KURRI）的46 MeV电子直线加速器（linac）耦合，在10 keV以下测量了Am-243、Pa-231、Th-229和Th-230的裂变截面和Np-237的俘获截面。采用背对背式双裂变室进行了裂变截面测量。用于捕获伽马射线测量的ar -气体比例计数器和用于中子通量/光谱监测的BF_3比例计数器用于测量Np-237捕获截面。在这种情况下，在对Np-237样品进行自屏蔽校正后，相对测量值被归一化为低能量区域的参考截面值。通过对所得结果的比较，对已有的实验数据和评价数据进行了研究。我们可以在某些核素/能量区域提供以前没有测量过的新数据。利用一对C_6D_6液体闪烁探测器，在12 m的飞行路径下和相对于^<10 b> B（n, α）反应的小于10 keV的直线飞行时间（TOF）法测量了Np-237的俘获截面。在对Np-237样品进行自屏蔽校正后，在0.0253 eV下将截面归一化到参考值181 b。对^<237>Np(n, γ)^<238>Np反应的KULS测量结果与TOF数据的能量展宽结果进行了比较。虽然在大共振区观察到一些小的差异，但它们之间大致一致。

The present status of nuclear data for actinide nuclides, Am-243, Pa-231, Th-229, Th-230 and Np-237, has been reviewed. Making use of the Kyoto University Lead slowing-down Spectrometer (KULS) coupled to a 46 MeV electron linear accelerator (linac) of the Kyoto University Research Reactor Institute (KURRI), the fission cross sections of Am-243, Pa-231, Th-229 and Th-230 and the capture cross section of Np-237 have been measured below 10 keV.A back-to-back type double fission chamber has been applied to the fission cross section measurement. An Ar-gas proportional counter for the capture gamma-ray measurement and a BF_3 proportional counter for the neutron flux/spectrum monitor have been used for the Np-237 capture cross section measurement. In this case, after the self-shielding correction in the Np-237 sample has been made, the relative measurement has been normalized to a reference cross section value in the lower energy region. By comparing with each of the results obtained, the existing experimental and evaluated data have been investigated. We could supply new data which had not been measured before in some nuclide/energy region.The capture cross section of Np-237 has been also measured with a 12 m flight path and the linac time-of-flight (TOF) method below 10 keV relative to the ^<10>B(n, α) reaction using a pair of C_6D_6 liquid scintillation detectors. After the self-shielding correction for the Np-237 sample, the cross section has been normalized at 0.0253 eV to the reference value of 181 b. The previous data have been investigated by comparing with the present measurement. The KULS measurement for the ^<237>Np(n, γ)^<238>Np reaction has been compared with the result obtained by energy-broadening the TOF data. General agreement can be seen between them, although some small discrepancies are observed in the big resonance region.