Teflon Examination
In this document, we outline an experiment performed at LLNL to evaluate the radiation sensitivity of polytetrafluoroethylene (PTFE) and a PTFE isomer, fluorinated ethylene propylene (FEP). We demonstrate that PTFE, a material currently used for assessing MicroCT system stability, shows higher radiation-dependent change in x-ray attenuation than FEP. Specifically, for a dose of approximately 1.44 x 10 3 Gy, the linear attenuation coefficient (LAC) of PTFE changes by 0.8 ± 0.1 %. During the same irradiation period, the LAC for FEP changes by 0.02 ± 0.1 %, which is within the statistical uncertainty of the measurement. Due to its higher resistance to radiation damage, we recommend that LLNL and partner labs operating under the Department of Homeland Security’s Explosives Division (DHS EXD) transition to the use of FEP as a reference material in place of PTFE.