Ted,
Another source of "mobile sources" are deliveries of radionuclides to hospital. Last year, a delivery van was stopped in New York City when the police detected it driving past their detector. These delivers occur frequently, as some places get unit doses delivered during the day.
Ted de Castro <tdc@XRAYTED.COM> wrote:
. . .
Two times I believe I even saw events similar to the industrial
radiography incident mentioned here. In one case I suspect a vehicle
with an open source driving up a road (like commonly happens when the
source does not retract). Unfortunately I was never able to confirm any
such event - but the simultaneous readings from two stations about a
mile apart on opposite hilltops with a valley in between with a road
running up the valley - are unmistakable.
. . .