Potential use of wallboard (drywall) for EPR retrospective dosimetry

Concern regarding the possibility of criminal or terrorist use of nuclear materials has led to an interest in developing the capability to measure radiation dose in a variety of natural and manufactured materials. Electron paramagnetic resonance (EPR) measurements of radiation dose following a radiological incident may aid in screening affected populations (triage) and in reconstruction of doses following accidents. One such EPR dosimeter is wallboard (drywall), a common construction material composed largely of gypsum (calcium sulphate dihydrate). We have identified the CO3− and SO3− dose-sensitive lines in drywall and developed a measurement protocol using the intensity of CO3− line. Proper background subtraction is a major difficulty, and we demonstrate a procedure based on alignment of a contaminant Mn2+ line. As a proof-of-concept, a wallboard panel was irradiated with a 60Co source, and a two-dimensional map of the absorbed dose was measured. While most aliquots yielded reasonably accurate doses, a spatially contiguous region of apparent dose-insensitivity in one panel was identified.