Radiation not coming from the source being measured: cosmic rays, natural radionuclides in soil, building materials and the body, radon, and in plants, shine from nearby systems. For people, natural background averages roughly 2 to 3 mSv a year. For instruments, background count rate sets the detection limit, so friskers and contamination monitors are used in low-background areas and alarm on counts above background.
Background's 300 counts here because of the shine from the letdown line, move the frisker round the corner.
Also heard as
- background radiation
- natural background
- bkg
Related terms
Frisker
The count-rate meter and probe kept at exits for checking hands, feet and clothing for contamination.
Survey meter
A portable instrument used to measure radiation dose rates or detect contamination in the field.
Shine
Radiation reaching a spot from a nearby source, through a gap or by scattering, rather than from what is being worked on.
Sievert
The SI unit for equivalent and effective dose, used to express radiation risk to people.