What common in a pulse induction and XRF (gamma ray fluorescence) gold detecxtors and its difference

[cko47]

We think that both methods use secondary radiation. But the second method (XRF) is more sensitive to small particles of gold. If it was possible to make the small generator of gamma radiation that it would advance development of such detector for detection of gold.
Photodiode Gamma Ray Detector was published in http://www.vk2zay.net/article/265 and http://www.maximintegrated.com/app-n...ex.mvp/id/2236

Shall be grateful for your comments on this theme.

[Waikiki_Sweep]

Why not? Just build a gamma ray laser and penetrate ground.
Probably analyzing of reflected light will give some data.
Just do not forget to wear lead boots and pants.
Probably government will not be happy so see such activity.

What if building a Muon (cosmic ray) Detector will give even more depth than gamma rays?
http://hardhack.org.au/book/export/html/2

Finally I hope to see an Underground Television Device some day and trow all my metal detectors to the dumpster

Also regarding that magic vision. I read somewhere that metal objects buried in sand may left some thermal anomalies on the surface. So probably some IR vision devices like those military using
infrared sniper scopes may show that spots.

[kt315]

please 15x15cm gold plate on 7meter depth sens. please also cup of coffee like a bonus+.

[Waikiki_Sweep]

please 15x15cm gold plate on 7meter depth sens. please also cup of coffee like a bonus+.

Easy! Drill a 7meter hole and put pinpointer in it.
I saw a few millimeters in diameter probe with metal screen to shield signals from one side. So you can even rotate it in ground to know direction to the target.

[Waikiki_Sweep]

Just joking. But.......... You can read in magnetometer section about that phenomenal success in finding small meteorites 100 ft. away or so because of ability to sense even small changes in magnetic field of Earth.
Sure you can not focus magnetic field to strike a target for a long distance. But you can follow that lines of global magnetic field already created by Earth.
Yea. Gold has no magnetic field. But you can make it. Put a huge loop 10 x 10 meter on the ground and send powerful impulse into it. All metal pieced in ground will conduct eddy currents and changing Earth magnetic field lines.
Even your gold plate 15x15 cm. 7 meters deep will do it. Sure it will work for one microsecond only. But with improving that magnetometers technology there is a chance to make it detected this way.
Even discriminate because with magnetometer you will already know what targets are magnetic.

And coffee you will boil on that MOSFET feeding impulses into 10x10 meters loop.

[cko47]

Why not? Just build a gamma ray laser and penetrate ground.
Probably analyzing of reflected light will give some data.
Just do not forget to wear lead boots and pants.

Now exist equipment (based at XRF) for detecting gold (small size) in ores. I saw image with this equipment for quick analyze in work. And without lead boots.

[Waikiki_Sweep]

That is great!!! For ores. Sorry, I just looking for solution to get those hundreds of gold and platinum rings buried under several feet of sand on ocean beaches. Can I hit it with Gamma rays?

[sinclairuser]

on the subject of meteorites, i once theorised a md based uridium decay detector, and was laughed at due to the size of such equipment.
at that time a small portable gamma ray generator would have probably have been just as laughable.
who knows what will be possible in 10 or 20 years!

[sinclairuser]

on the subject of meteorites, i once theorised a md based uridium decay detector, and was laughed at due to the size of such equipment.
at that time a small portable gamma ray generator would have probably have been just as laughable.
who knows what will be possible in 10 or 20 years!

of course i meant to say gamma detector not generator!

[Tepco]

Main issue with portable XRF is relatively low energy X-ray used with very limited penetrating power. With even higher energy portable units, millimeters at best in any dense medium, otherwise almost just surface. Some sources use beryllium oxide exit windows, rays are unable to penetrate even thin glass wall. Isotopes are not better either, except if you use something really not recommended, like Co60.

[cko47]

From 3 types of radiation (alpha, beta and gamma) gamma radiation have largest penetration ability. Layer of concrete with thickness 16 cm can decrease gamma radiation in 10 times. And water with thickness 33 cm decrease in 10 times . Therefore this type XRF spectroscope can detect gold in large distance (<= 20 cm) .

[Tepco]

Not that simple at all. In XRF there is big difference between penetrating power of incident beam and detection depth. Penetrating power also varies slightly with beam energy (that is, wavelength, not intensity) and material type, so not all gamma will decrease equally. For example, Co60 decay (I mentioned, highly not recommended to be anywhere near it) produce gamma of around 1.2-1.3 MeV, (this is HUGE!), compared to XRF energies of ten's of KeV at best (small dental X-ray produce more). At this energy, HVL (half value layer, thickness to reduce radiation by half) in concrete is around 5cm, so after 10cm it will be 1\4, after 15cm 1\8 etc (so, at this energy 16cm concrete will attenuate radiation 10 times). Ra226 decay produce, for example, around 186KeV gamma, HVL is around 2cm, co 16cm concrete will attenuate it some 250x. At around 50KeV, HVL is around 4mm, so attenuation in 16cm concrete is around 1000 billion times. You can find exact numerical data and how to calculate, for different energies, materials etc. Concrete density is around 2.35, for soil typically 1.7.


Now, even worst part: XRF characteristic emission lines for gold are centered around 10KeV for L, and 70KeV for K transitions. At these wavelengths gold will “fluoresce” in X-ray light, and spectra emitted is used for identification. Even with K lines excited with high enough incident energy, HVL is some 5mm. Usually, L lines are used. I'm lazy to search and calculate values now, but not millimeters, more like less than millimeter is what you can expect. Keep in mind, no use of too high energy and large penetration power of incident radiation, this may be good to X-ray something, inspect welds, or asses health of some three, by measuring it's density etc. Even if you can excite fluorescence at larger depth, you wont be able to detect it, no use of that, actually large amount of secondary photons scattered around will jam your detector so you probably won't able to see anything.


Detectors are simper than this.

[cko47]

Thank You. The very useful information. I should chew it.