The China Spallation Neutron Source (CSNS) is a multidisciplinary research platform. Its high-energy 1.6 GeV proton beam serves various applications in aerospace devices and particle detector testing. However, certain irradiation applications and high-performance detectors require different beam energies. A degrader was designed to adjust the proton energy to a desired range.

This study presents a reasonable degrader scheme for the 1.6 GeV proton test beam at the CSNS.

The physical process of the 1.6 GeV high-energy proton beam passing through a degrader made of either of three different materials (iron, copper, and tungsten) was simulated using FLUKA, a Monte Carlo particle transport code. Parameters such as the degrader thickness, the energy deposition, the outgoing proton beam intensity, and the irradiation dose were determined through simulations. The optimal degrader material was identified. In addition, a continuously adjustable structure of the degrader was given.

Iron displays slight advantages in terms of energy deposition and radiation dose distribution, compared to copper and tungsten. Furthermore, the phase-space distribution of the outgoing proton beam and the secondary pion beam were also given, providing important references for future beam-line design.

An optimal degrader structure made of iron for the CSNS high-energy proton beam is proposed. The secondary pion test beam is also feasible at the proton test end station. This is a significant development for future engineering design.