But a metal detector can't detect the kind of explosives that were sewn into his clothes.
And if, on top of the bright pulse, a smaller pulse of just the right type is sent, the detector can be forced to record a one or a zero.
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The harder part will be designing a detector that can distinguish between two adjacent letters on a DNA strand, which are half a nanometer apart, a small fraction of the wavelength of light.
The harder part will be designing a detector that can distinguish between two adjacent letters on a DNA strand, which are half a nanometer apart, a small fraction of the wavelength of light (which makes it impossible to see them).
While each sensor has its advantages, life-safety can be affected if the wrong detector is used for specific kinds of fires.
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Home fires are often smoldering but can also be flaming, so the detector that is chosen is critical because of the necessity of early warning.
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By tuning the quantum cascade laser and measuring how much of the infra-red radiation is absorbed on its way to a detector, hazardous gases in between can be identified.
Light ones are more easily deflected than heavy ones, so the two forms of carbon get separated, and when each atom reaches a detector at its expected arrival spot, it can be counted.
Other ideas include building a detector to see if the spin of an atomic nucleus can be measured, or using the technique as an ultrasensitive antenna.
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Otherwise the detector is made immortal, so that subsequent, similar intrusions can be detected.
Working on a leash, one of the group's trained African rats can clear an area in 30 minutes that would normally take someone with a metal detector two days, Mr. Cox said.
"If the sudden frequency change is neglected, then after only eight hours, a complete rotation of the pulsar is lost in our counting, and we can no longer determine at which rotational phase the gamma-ray photons reach the detector aboard Fermi, " Pletsch explained.
That is not very exciting by itself, but this detector counts single photons (the particles of which light is composed) and can do so at room temperature.
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