Th-232对钍铀燃料循环和加速器驱动次临界系统具有重要意义，它的中子诱发裂变截面在过去的几十年中一直受到关注。但是不同的实验测量之间之间仍然存在一些偏差，某些能区的偏差在10%以上。因此，我们迫切需要测量Th-232的中子诱发裂变截面，特别是给出分歧较大能区的测量结果。通常的裂变截面测量都是以U-235的裂变截面为参考标准。但是，n-p散射的反应截面更准确，且U-235的裂变截面通常是相对n-p散射进行测量的。因此本项目考虑直接以n-p散射为标准，精确测量Th-232的中子诱发裂变截面。本实验将在CSNS反角白光中子源上开展，测量由2MeV(Th-232裂变阈值)-80MeV能区的中子诱发Th-232裂变的反应截面。测量精度在2-20MeV范围为5%以内，在20-80MeV范围为8%以内。

Th-232 is very important to both Th/U fuel cycle and Accelerator Driven Sub-critical System, therefore its neutron-induced fission cross section attracted a lot of attentions in last decades. However, discrepancies still exist between different measurements. In some specific regions, the discrepancies are even larger than 10%. As a consequence, it's quite necessary and urgent to measure the neutron-induced fission cross section of Th-232, especially in the energy regions where the discrepancies are large between different measurements. The 235U(n,f) cross section is usually used at the reference for the fission cross section measurement. However the n-p scattering cross section is more accurate. Furthermore, the 235U(n,f) cross section are usually measured relative to n-p scattering. Therefore we are proposing an accurate measurement of the Th-232 fission cross section relative to n-p scattering. The experiment will be conducting at CSNS Back-n white neutron source, the fission cross section of Th-232 induced by neutrons from 2MeV (fission threshold of Th-232) to 80 MeV will be measured. The uncertainties for neutron energy range from 2 to 20 MeV will be controlled within 5%, the uncertainties from 20 to 80 MeV will be less than 8%.