Re: NMR combating terrorists

Wow, did I actually find the second sober person in sci.physics.pub?


The Ghost In The Machine wrote:
> [1] How many tesla would one need?

It depends on many factors such as what element(s) you are scanner for
and how sensitive you are able to make the scanning hardware.
There is guy who created a device that measures the earths magnetic
field. It's not a big discovery or anything, but it shows what even a
*little* amount of cleverness can create. So how many Teslas does it
require? Try 1/20000 of a Tesla. Sure, there are the magnetizing
coils that first align the magnetic moments, but that does not need to
be at any fixed strength. It is the magnetic field of earth that
changes the frequency from the hydrogen in the bottle of water that he
uses. If the magnetizing coils generate less current that only means
the EM that comes from the hydrogen will less. So he has a magnetizing
coil on the outside. Inside is a bottle of water that is wrapped
inside a receiving coil. He magnetizes the outside coil and then
releases it. This aligns some of the protons and when this field is
released then some of the protons realign back to the earths magnetic
field or some align in random positions. Anyhow, this realignment
generates the EM that varies according the earths magnetic field, which
is ~1/20000 of a Tesla.



> [2] Signal processing may involve a time/quality tradeoff. What
> parameters of time, false positives, false *negatives*, and
> power consumption are you envisioning here?

Now you want me to give out the secret? How do you think the U.S.
government would think if China or better yet Iran learns of it. I
know that's not what you want to hear ... who wouldn't. If you people
can provide help in the area of NMR or if you have a better way of
detecting the element type then I'll take care of the software end.
Here is what I can presently do with my software breakthrough and my
limited knowledge of physics ->

~~~~~~~
There are two designs. Design #1 can aquire a 3D image of the area
from just one 180 degree rotation of the devices antennas. Design #2
can aquire a 3D image from just 256 * 180 degree rotations of the
devices antenna. In design #1 we can get various false artifacts
imbedded in the 3D image. Basically this is caused by ground that
contains large changes in ground type. For example, if the antenna is
right over a split in ground type that goes from say granite to sand.
Although design #2 takes say 256 times longer to scan the area, it
creates a clear 3D image. The number 256 is based on the desired
resolution in the longitude vector of the 3D image. So if you wanted a
resolution of 512 then it would take 512 times longer. In both designs
the device generates a known signal of pulses. The time between each
pulse varies and is a known time delay. This time delay that varies
between each pulse is signal code I was talking about. The software
sends out a known signal of so-called 1's and 0's; e.g.,
1101010001100100111111001101010001110010101. The longer the signal is
the better the software can hear the incoming EM reflection. It seems
most people in this thread cannot believe that any device could receive
a reflected signal that reversed through 10's of thousands of feet
through solid earth at say 100MHz much less 10GHz. At 10GHz most will
tell you that signal does not penetrate the earth very deep at all--
few inches. That is an incorrect way of thinking. Perhaps at 10GHz
99% of the signal is absorbed and reflected in the first foot, but at
10 feet there is still a fraction of a % of the signal and at 10000
feet there is still a fraction of the signal. Remember, the software
can pick up on the faintest signal amongst a sea of noise. The
incoming signal may be 1 millionth of the ADC's single bit-- it doesn't
matter. As long as there is noise in the ADC input then the software
can pick up on as small of signal as it wishes. So in that sense,
noise helps. :-) On the other hand the computer does have limitations
such as memory. For example, obviously it would be very time consuming
for the software to utilize a signal code that's say 1E+14 bits.
That's a lot of memory. In such a case the software would have to use
some type of memory such as a huge real of memory tape rather than fast
RAM. The more time the software has to sample the signal then the
better it can hear the signal. Also the stronger the emitted signal
obviously equates to a stronger received signal.
The EM frequencies used depends on the situation. Obviously lower
frequencies traverse better through solid matter, but it requires more
time to generate a 3D of the same resolution. Believe it or not, the
wavelength of the radio is not a limitation of resolution. For
example, such a device could generate a 3D picture down to 1mm in
resolution with a radio wavelength of 1000mm.
~~~~~~~


BTW, the above mentioned designs are not NMR. It is leading edge GPR
that has not yet been released to the public ... and may never be
released to the public for a long time for security reasons. With such
technology one could remote view a building that is miles away. On the
other hand, such technology would pier inside the earth for 10's of
miles. It could find a person buried inside any rubble. The
technology can be used with any wave from sound to gamma rays. You
could plug it into a visible light microscope and see far smaller
objects than the visible wavelength. Such technology could map the
solar system of objects. You could see inside planets, etc.



> (There's a *lot* of issues here, and getting more than a few microounces
> of the stuff would be extremely difficult anyway.
> I'd expect Al Qaeda would have some major problems
> doing it right, but not much problem doing it wrong,
> although ideally they'd blow themselves up in the
> attempt. [One can hope! ;-) ])

Al Qaeda has the same philosophy as China as far as patience. I think
they learned long ago that a rushed job doesn't pay off. They have
TIME on there side. Thankfully you scientists also have time on your
side. PLEASE, get to work and start thinking. I am also working on
this, but I have not taken the years of my life to study science, just
computer programming and some basic science. I am pretty darn good at
classical EM though.


> [4] According to the Bureau of Transportation Statistics (figures! :-) )
> South Louisana handles 200 million tons a year, or
> 100,000 tons or 91,000 metric tonnes an hour (assuming
> 40-hour 5-day workweeks), That's at least 50 shipping
> containers a minute.

That is no problem. Five scanners that takes 5 seconds per scan could
keep up with that flow. So say 10 scanners would do great and result
in no delay, unless the scanner finds illegal material.

So could you confirm the following? That is, is it true that there's
matter that can be used in a dirty bomb that is not radioactive. If
that is true then obviously radio active sensors will not work. In
such a case then NMR scanners would work.

Paul

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