Translation guide
The term "background radiation" refers to the low-level ionizing radiation present in the environment from natural and artificial sources. In Japanese, the most common equivalent is 自然放射線 (natural radiation), but the direct loanword バックグラウンド放射線 is also used in technical contexts.
The general concept of ambient ionizing radiation from natural and artificial sources.
Literally 'natural radiation'. This is the most common and natural way to refer to background radiation in everyday and educational contexts.
The faint thermal radiation left over from the Big Bang, filling the universe.
In casual contexts, Japanese speakers often simply say 自然放射線 (natural radiation) or even just 放射線 (radiation) when the background nature is clear from context. The loanword バックグラウンド放射線 is understood but sounds technical.
We are constantly exposed to background radiation.
Direct loan translation. Used in scientific and technical contexts, but less common in general speech.
It is necessary to subtract the background radiation of the measuring instrument.
Literally 'environmental radiation'. Often used in official or monitoring contexts, such as by government agencies.
We will publish the results of environmental radiation monitoring.
Standard term for cosmic microwave background radiation.
The cosmic background radiation is considered evidence of the Big Bang.
More specific term including 'microwave'. Used in astrophysics.
The temperature of the cosmic microwave background radiation is about 2.7 Kelvin.