Nuke detectors to ring New York, official says

CNN(ughh!) ^ | Feb 9th | CNN(ughh!)

[rjp2005]

New York City will be protected by a ring of devices to detect nuclear or dirty bombs before the end of the year, the Department of Homeland Security said Friday.

A dirty bomb is one that spreads radiation without employing a nuclear explosion.

The Department of Homeland Security hopes the circle of sensors will give warning if a bomb is transported into the city by land.

[Postman]

I thought the sarcasm would be obvious. So, just for you, here is the marker I left out /s

[Talkeetnaman]

There are a few different ways to detect radioactive elements passing a given point. One of the way is to use banks of Geiger Tubes. These are not very sensitive by themselves, but in a bundle they do a pretty good job. A more sensitive method is to use a scintillation detector using a photo multiplier tube with a cesium-idoide crystal.These are very sensitive and would probably pick up even a small rise in background radiation through a lead pig used to carry the radioactive elements. There are also ways to detect large amounts of lead or any other element. I know of some ways to defeat some of these, but I am sure if I were to list them here someone would get upset. I like to think the pros have it in order.

[Postman]

Thanks for the information. I agree with you about the pro's having it in order on this and many more issues than my brain can easily handle. It's become a very complex world, hasn't it.

[UpAllNight]

--Erm... heavy lead shielding on over the package will pretty much foil these detectors. Unless these are not radiation detectors, I find this a complete waste of taxpayer money.--

Erm ... They would pull over and inspect more closely those found carrying lots of lead in the vehicle.

[UpAllNight]

-- and would probably pick up even a small rise in background radiation --

They would be looking for specific radiation energies, not just a rise in background.

[farlander]

And, how would you detect a heavy lead shielded crate among buncha other crates on a truck ?

[UpAllNight]

--And, how would you detect a heavy lead shielded crate among buncha other crates on a truck ?--

X-rays.

[farlander]

Soo, set up checkpoints on major routes into NYC and make all mid-size to large trucks go through an XRAY machine ?

I'm thinking it'd be far more feasible to institute a MAD-like doctrine. Publish a list of cities in lands related to terrorism, and, say for each act of terrorism against our interests we will pick a settlement off the list at random, proportional to the attack, and turn every living being at that location into fuel-air induced or radioactive vapor.

After a couple of incidents, as they figured out we're serious about this, it would all stop. They only respond to strength.

[UpAllNight]

--I'm thinking it'd be far more feasible to institute a MAD-like doctrine. Publish a list of cities in lands related to terrorism, and, say for each act of terrorism against our interests we will pick a settlement off the list at random, proportional to the attack, and turn every living being at that location into fuel-air induced or radioactive vapor. After a couple of incidents, as they figured out we're serious about this, it would all stop. They only respond to strength.--

How would that stop the terrorists? It wouldn't.

[farlander]

It would after some of the cities on the list were destroyed. The rational people that never the less despise us, but wish to continue on this earth would get the terrorists.

I'm not saying stop intelligence work, or don't bother. All I'm saying 'rings of detectors' are all to easily foiled, and, therefore not cost effective. I'd prefer the money goes to intelligence gathering efforts at tracking and disrupting cells.

[chimera]

As I recall the purpose of those photodetectors was to confirm the actual detonation of the device as a final confirmation of a strike. NORAD pretty much had in hand the radar/satellite-based information. This would enable the launch-on-warning capability. But if the decision was made to forego LOW then it was felt useful to have ground-based confirmation of a successful strike by the enemy prior to launching retaliatory strikes. It was not intended as a preventative measure.

Not a lot of people know it, but there were also radiation monitors placed at various locations to supplement the photodetectors. These were designed to be most sensitive to the kinds of neutrons (in terms of energy) released in thermonuclear reactions, and little else. That way there would be little chance of spoofing them. Again, information only, not preventative.

[oust the louse]

I think they should also blast this via TV and video and distribute the video to any Muslim country so they know to get it in early...hurry and warn the terrorists!

[Talkeetnaman]

Yes on the different energy levels of radioactive element. These are measured in eV and Mev Levels with the proper equipment. They even us neutron generators using tritium and deuterium where you can beam this onto something and measure the gamma ray levels coming back. All elements emit a different level when doing this These are used in oil wells where the oil companies can find all the different elements they drill through. They can even find gold.

[Talkeetnaman]

These are not just photo detectors we are talking about, but photon detectors. What happens is when a gamma ray passes through a cesium iodide crystal it produces a photon. This goes to a PM or photo multiplier tube. It converts that on photon into one electron at the input but but the time it reaches the back of the tube it produces a measurable amount of current at a voltage consistent with the type of material that is producing the gamma ray. Every element has its own signature

[Timmy]

Erm... heavy lead shielding on over the package will pretty much foil these detectors. Unless these are not radiation detectors, I find this a complete waste of taxpayer money.

Erm... No, it won't. Gamma radiation is very easily detected over great distances and the amount of shielding required to smother it would be enormously large and heavy.

[farlander]

I stand corrected.

[chimera]

Yes, I was building NaI(Tl) detector arrays back in the early 1970s for medical imaging applications. One of the jobs we did for the DoD was developing an airborne system for fallout signature analysis. We eventually replaced that with a high resolution Ge(Li) system which evolved to a hyperpure Ge system. Those are tricky because you need a fair amount of shockproofing from aircraft vibrations, otherwise you get a lot of electronic noise from microphonics in the crystals. The NaI(Tl) systems were a little more robust on the score but PMT drift was a problem (temperature changes).

But there were also ground-based photodetectors (visible light, not gamma rays) deployed as well. The nice thing about those was because of the intensity and time characteristics of a nuclear detonation (double flash signature) you could build in a threshold so that ordinary events (reflected sunlight, for example) would not give a false indication. The time response of those had to be very fast to capture the time signature, but if you did it right it was possible. For the time (1970s-era technology) those were quite sophisticated.