Aren't gieger counters detecting molecules that would be off the property?
if you read post 88, apparently even thermal imaging of any law enforcement person using their sense of smell - is also unconstitutional.
I hate to say this - but I bet the FBI suspends this program now that it has been "outed". the muslims and the ACLU are going to go into court over this.
No. They detect radiation.
In general Geiger counters are designed to detect ionizing radiation. They detect either gamma rays and X-Rays(very short wavelength electromagnetic waves) or particles such as Alpha particles (helium nuclei) or Beta particles (electrons given off by radioactive decay. Some only do the Gamma and X-rays.
These are all much smaller than molecules. The Gamma and even X-rays are readily absorbed by air, but creating secondary ions in the process. The Beta particles too are short ranged, (Good thing since your color TV, tube type, emits lots of them, even after they started putting in special screens). Alpha particles, OTOH, will drift around, although they eventually pick up a couple of electrons (creating ions of whatever they got the electrons from) and become ordinary helium atoms.
All these kinds of radiation/particles are given off during radioactive decay processes. Thus while the GC is detecting the ionizing radiation directly, indirectly it's detecting whatever atoms are emitting it. Could be americium, as in smoke detectors, or certain isotopes of Thorium, Cobalt, Uranium or Plutonium as well as many other "heavy" elements, or even lighter stuff like Sodium or Carbon (that's part of how carbon dating works, the Carbon-12 is unstable, albeit with a pretty long half life).