Neutron Resonance Imaging of a Au-In-Cd Alloy for the JSNS

The Japan Spallation Neutron Source (JSNS) at the Japan Proton Accelerator Research Complex (J-PARC) was developed as a 1- MW spallation neutron source. A Ag-In-Cd alloy was used as the decoupler material in two decoupled moderators. Although the Ag-In-Cd decoupler brings about superior neutronic performance, it has the disadvantage of high residual radioactivity. A Au-In- Cd alloy has been proposed as a solution to this problem. Recently, we successfully produced a ternary Au-In-Cd alloy. The alloy composition was 74.9 at% Au, 0.5 at% In, and 24.6 at% Cd. The distribution of the elements in the alloy was first determined by energy-dispersive X-ray (EDX) analysis. However, it was difficult to measure the In distribution by EDX because the amount of In is very small, and its spectrum is similar to that of Cd. Therefore, pulsed neutron imaging using both a time gated camera system and a multi-channel plate detector was performed to measure the elements in the Au-In-Cd alloy. The analysis was performed at the BL10 in the JSNS on samples of the Au-In-Cd alloy, an In foil, and two Au foils. With this technique, the distribution of Au, In, and Cd in the Au-In-Cd specimen was distinctly determined.