Energy Distribution of Proton Beams Degraded by Rotating Aluminum Foil Wheel for Space Radiation Simulation

Radiation effects are a critical concern in the space industry, particularly for electronics operating in high-radiation environments. The TAMU Cyclotron Institute provides simulated space radiation using proton beams across a wider energy range. To minimize downtime when changing beam energies, a rotating degrader-wheel is used to lower the energy of a fixed high-energy proton beam (e.g. 45MeV) by passing through aluminum foils of varying thickness. While this method offers faster turnaround for users, it results in broader energy distribution, especially at lower final energies, which may impact experimental precision.

This project aims to characterize the energy distributions resulting from proton beam degradation at selected energies (e.g. 30MeV, 15MeV, 7MeV). Calibration was performed using known peaks from a Thorium-232 source.

Experimental results were compared with SRIM (Stopping and Range of Ions in Matter) simulations and hand calculations using PSTAR (Proton Stopping power and range TARget database) to validate expected energy loss and spread. Findings agree that lower energy degradations (e.g. 45MeV to 7MeV) result in significantly broader energy distribution. These results provide critical insight into the tradeoff between speed and energy resolution, informing TAMU Cyclotron users whether the convenience of the degrader-wheel use outweighs the uncertainty introduced by the energy spread.