What factor primarily influences the calibration of a nuclear gauge?

The calibration of a nuclear gauge is fundamentally influenced by the known density and chemical composition of the materials being measured. This is because nuclear gauges work by emitting radiation and measuring how much is attenuated or scattered by the material. Different materials interact with radiation in unique ways based on their density and atomic composition.

For accurate calibration, it’s essential to have precise knowledge of these characteristics, as they directly impact the gauge's readings. If the density or composition changes or is not correctly understood, the measurements produced by the gauge can lead to significant errors. Calibration ensures that the gauge responds accurately under specific conditions and uses appropriately characterized reference materials.

While environmental factors like temperature can impact radiation detection, they are generally less critical to calibration than the intrinsic properties of the materials. Similarly, while the size of the radioactive source and the age of the gauge may affect overall performance and safety, they do not play a primary role in establishing the calibration against known benchmarks. Thus, the known density and chemical composition remain central to the calibration process.