Experimental Data of Bi Slab Shielding in Integral Measurements at CNDC

These experiments were conducted using a 14 MeV deuterium-tritium (D-T) neutron source generated by a 400 kV nanosecond-pulse neutron generator. The experimental setup included a dual-axis electric sample stage for precise positioning and alignment of bismuth slabs, a multi-layer collimation system to reduce background noise, and a comprehensive detection system for accurate measurement of neutron leakage spectra.Measurements were carried out using bismuth slabs with effective thicknesses of 5 cm, 10 cm, and 15 cm, achieved by combining two large bismuth samples with dimensions of 30 × 30 × 5 cm and 30 × 30 × 10 cm.

Experiments covered six angles: 47°, 58°, 73°, 107°, 122°, and 133°. The bismuth used in the study had a purity exceeding 99.997%, ensuring minimal impurity effects on the results. Time-of-flight (TOF) spectra were obtained for neutron energies ranging from 0.8 to 16 MeV, with pulse time distributions reconstructed using the MLEM algorithm.The detection system included a primary Φ2 × 2-inch EJ301 liquid scintillator for measuring neutron leakage, two Φ0.5 × 0.5-inch EJ301 neutron monitors for source neutron pulse recording, and a silicon carbide (SiC) detector to differentiate between alpha particles from the D-T reaction and protons from D-D reactions.