Work with me here. We install video cameras in plain sight to detract robbers. We install those annoying "YOUR SPEED IS..." machines on roadways to warn speeders throughout the country. We place barriers along bridges so that jumpers won't...jump. We place rollover warnings on the visors of cars to warn us not to go too fast on a curve. Now I could go on and on.

One question: why NOT make public that radiation detection devices will be placed in large gathering spots? What's the harm in divulging that information -- wouldn't it be some kind of deterrent? I don't know. I guess the video cameras haven't stopped bank robberies so your guess is as good as mine.