[Indie]

I read a novel years ago (forgot the title) where a nuke was hidden in a building on an upper floor. In that novel, it was stated that from the ground, the NEST teams can only scan up to about the 4th floor with their equipment. Any knowledge of this?

[judicial meanz]

You can scan a lot more than four floors. Radiation has an effect called "groundshine" that makes it radiate in 360 degrees from its point of rest.

An object located in a 4th floor apartment would "shine" radiation up, down, and to the sides. Once you get a "stray" gamma reading, you simply triangulate it to the source.

Its easy to tell "stray" gamma from radon and naturally occuring radiation. You look for a spike among natural radiation backgrounds, and then narrow the spike down to a point of origin.

Remember, however, that you are probably looking for something barely above background level and its a treacherous thing to pick out unless you are really good at it.