Shielding is not a crude term, it is indeed used as technical language in the world of radiation safety. You are also using the term attenuation incorrectly, as sibling comment points out.
Shielding in radiation safety means attenuation to a safe level. But for detection, that is irrelevant because radiation detectors can be very sensitive, such that even very minute quantities making it through a "shielding" are still sufficient. When in doubt, you just increase integration time to almost forever and you will still get a sufficient number of particles to get a measurement.
thyristan|10 months ago