**3. Assemblies**

The experimental assemblies are composed of polyethylene shell, depleted uranium shell, and ThO2 cylinder with a D-T fusion neutron source and thorium samples.

#### **3.1 Polyethylene shell**

One can assume the elastic scattering cross sections of H and C, which are widely used as standard cross sections [18] to be reliable. The polyethylene (PE) shell is adopted for checking the method of measuring the 232Th reaction rates. The inner radius (IR) and the outer radius (OR) of the PE shell are 80 and 230 mm [11], respectively. Five slices of ThO2 (concentration > 99.95%) foils are put in the radial channel at 0° to the incident D+ beam, as shown in **Figure 1**. The mass and size of foils are about 4.2 g and ϕ30 × 1 mm, respectively.

**Figure 1.**

A D-T fusion neutron source is located in the center of the shell. The 14 MeV neutrons are produced by a neutron generator at INPC. The energy of D+ beam bombarding a T-Ti target is 225 keV. An Au-Si surface barrier semiconductor detector is at an angle of 178.2° to the incident D<sup>+</sup> beam in the drift tube and used to measure the absolute yield by counting associated α particles [19, 20]. D-T neutron yield is about 3 × 1010/s.
