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

本文评述了锕系核素Am-243、Pa-231、Th-229、Th-230和Np-237的核数据现状。利用京都大学铅慢化谱仪（KULS）和京都大学研究堆研究所（KURRI）的46 MeV电子直线加速器（LINAC），测量了Am-243，Pa-231，Th-229和Th-230以及Np-237的俘获截面已在10 keV以下测量。背式双裂变室用于裂变截面测量。用于俘获γ射线测量的Ar气正比计数器和用于中子通量/能谱监测的BF_3正比计数器已用于Np-237俘获截面测量。在这种情况下，在Np-237样品中进行自屏蔽校正后，相对测量值已被归一化为较低能量区域中的参考截面值。通过比较所获得的每一个结果，现有的实验和评估数据进行了调查。在12 m的飞行轨道上，用一对C_6D_6液体闪烁探测器测量了Np-237在10 keV以下相对于~<10>（B）（n，α）反应的俘获截面。在对Np-237样品进行自屏蔽校正后，将0.0253 eV处的截面归一化为参考值181 B。通过与目前的测量结果进行比较，对以前的数据进行了研究。对^<237>Np（n，γ）^<238>Np反应的KULS测量与能量展宽TOF数据的结果进行了比较。虽然在大共振区观察到一些小的差异，但可以看出它们之间的一般一致性。

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.