Are US nuke bomb dectors at air and sea ports really effective,if lead can be used to block neutrons?

Question

ARE THEY JUST FOR SHOW,TO MAKE US FEEL SAFE,

Answer 1

Yes since lead is not a great shield for gammas

Answer 2

Depending upon the grade and type of isotope used to make this bomb will determine the effectiveness of a dosimitry detector. Fast moving neutrons, neutrons, gammas, xrays, betas are some of the forms of particles released from a radioactive isotope.
But remember to make a bomb out of a neutron source would not be wise since the isotope would require a great deal of H2O to remain stable, or not to allow it to explode prematurely.
So do the detectors and scintillators help detect a bomb...yes very much so.

Answer 3

Lead is almost completely useless as a shield against neutrons. To shield neutrons, you use different materials.

Neutrons hitting a dense material like lead are absorbed by the lead nuclei, changing them to an unstable, radioactive isotope that emits gamma radiations -- so lead shielding of neutron emitters actually makes it EASIER to detect them.

The detectors are very sensitive, but it is always a tradeoff between sensitivity and false alarms due to the background radiation.

Answer 4

They can best be described as somewhat adequate for the job. They mainly detect gamma rays, and lead shielding isn't all that effective in blocking all of them from escaping from a nuclear device.

Answer 5

Just for show. If you think a terrorist who manages to get his hands on a nuke is going to stick it in a shipping container and cross his fingers, I've got a bridge in Brooklyn for sale.