Observations with a crystal

You know, I think fortune tellers use crystal balls or such. I was taking a spectrum with my crystal and PMT.

Just testing some pre-amplifier circuits. You can see the spectrum build slowly, auto scaling keeps it nicely full screen.

Slowly building, background, suddenly it started increasing rapidly, I heard a jet, I am sort of in the approach path of a military air-base.. It was not an F16, I think, could have been an Euro fighter, maybe F15, maybe something larger... The spectrum increased rapidly, and acquisition returned to normal as the plane sound went away. I estimate the height at about 1000 feet when it passed over here. I was so fascinated looking that that spectrum change that I forgot to go look at that plane, no time, took just a few seconds..

So I thought about this for a week, and concluded that that airplane was carrying very radioactive material, so probably a nuclear weapon.

But I dunno if such a simple crystal and PMT setup can detect a nuclear bomb

1000 feet away? Any comments? If this was an Euro fighter, then Germany has the bomb. Now how is that Dr Watson? I think Euro fighter because I have this PC game, that sort of sound. F16 is common here, they fly over all the time, I know that sound. But maybe F15, and a US bomb, that is possible too. Or interference in my premap from the radar of that plane? I did not save the spectrum, I should have. Setup was not calibrated for energy at that moment either.
Reply to
Jan Panteltje
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My guess is that the PMT is microphonic.

My experience with nuclear weapons is limited. But when ever I have been in a room with a bunch of them, I was wearing a film badge or other device to determine if I was subjected to any radiation. And the room itself had radiation monitors. Never got any radiation above background. The radiation was well below the amount of radiation one gets from eating a banana.

=20 Dan

Reply to
dcaster

sound went away.

I think that the answer is here:

--
Rich Webb     Norfolk, VA
Reply to
Rich Webb

On a sunny day (Sun, 23 Oct 2011 04:42:38 -0700 (PDT)) it happened " snipped-for-privacy@krl.org" wrote in :

Yep, bananas are 'hot'. But my PMT is not microphonic, I can tell you that. But these are very high quality crystals from a US national laboratory...

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Did you see my movies for 'background'?
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This is with just a darlington on the PMT anode driving a LED, with about 800 V or 900 V (for a 1250 V nominal PMT), with just background. If you scope it there are zillions [tm] of pulses. Without the crystal the LED stays off.

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Reply to
Jan Panteltje

On a sunny day (Sun, 23 Oct 2011 08:31:22 -0400) it happened Rich Webb wrote

A lost nuculear bomb was found of the coast of the US by some guy using sensitive detection equipment. That is with many meters (or feet if you have not heard of metric) water in between.

Reply to
Jan Panteltje

ensitive detection

in between.

But Jan can't find the URL that tells us what the finder was actually looking at

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talks about a guy that thinks knows where missing the bomb ended up, but it doesn't look as if anybody less credulous than Jan took him seriously.

It looks as if lost nuclear bombs aren't all that easy to find ...

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-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

sound went away.

Unlikely. If you could detect the radiation 1000 feet away, it would be lethal to the pilot.

John

Reply to
John Larkin

plane sound went away.

The "evacuation procedures" of the 50s and 60s were such a joke.

If you 'see' the flash, it is already too late. Even if you were not looking.

Pretty much, "If the flash "sees" you, you're done." Exposure doesn't require that one knows that one was exposed.

Reply to
StickThatInYourPipeAndSmokeIt

What frequency was the xtal cut for?

Mark L. Fergerson

Reply to
alien8752

On a sunny day (Sun, 23 Oct 2011 09:20:42 -0700) it happened John Larkin wrote in :

plane sound went away.

Perhaps.

Reply to
Jan Panteltje

On a sunny day (Sun, 23 Oct 2011 10:06:52 -0700 (PDT)) it happened " snipped-for-privacy@bid.nes" wrote in :

This is not about quartz and resonators.

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Reply to
Jan Panteltje

How did you test it? The dynode spacing changes, the capacitance goes with it, and your evenly-spaced voltages on the elements become uneven. Gain is exponential in applied voltage, so the high-gain fluctuations are greater than the low-gain ones, and that means there's a net average output signal. Any flexure of the cathode can be a signal source, too.

It's a vacuum tube, you'll want to vibrate its base with a swept audio generator to test. There's other microphonic possibilities, too (like, some materials have metastable states and radiate when warmed or stressed - that's how thermoluminescent radiation badges work).

Reply to
whit3rd

plane sound went away.

How about some kind of radar interfering with your electronics?

--

John Devereux
Reply to
John Devereux

plane sound went away.

It is much more likely that Jan's badly constructed device is objecting to being illuminated by the fast jets ground attack radar.

I sometimes attract Harriers or Tornadoes as my SCT scope acts very much like a cube corner reflector at their radar wavelengths and they fly over me to see what it is. They are on their way to a live fire range so this could be a bit interesting if they were trigger happy.

I can tell if they illuminate me with their IR targeting laser as that saturates my CCD camera. Typically they are flying at 300-400 ft.

--
Regards,
Martin Brown
Reply to
Martin Brown

plane sound went away.

Would it have reacted to radar?

Reply to
David Eather

They do have ground looking radar for landing, I think its for altimetry.

Cheers

Reply to
Martin Riddle

plane sound went away.

Lots of people saw the flash and survived in Hiroshima. Lots of people stood in the open and watched nuke tests in New Mexico. Bombers dropped H-bombs and the crews got away fine. Light travels a long way farther in air than ionizing radiation.

John

Reply to
John Larkin

No, a HIGH-power radar transmitter is much more likely. Due to a BUNCH or horrendous accidents in the 1960's, it is pretty rare for US aircraft to carry nuclear weapons on routine missions. They do fly them around for supply and maintenance tasks.

You should have LISTENED to the pulses from the detector, I'll bet you would have heard a tone, probably an intermittent tone as the radar beam was swept back and forth. The F-15 has 3 radars that look through each other's antennas, at different frequencies. The search radar runs at an insane repetition rate, the others are a bit slower. The search radar is looking out to 100+ miles, with a somewhat defocused beam, so it is a very strong pulse. I'm not sure if the other radars are even on except when their functions are in use (target tracking and synthetic aperture imaging). Also, there is a radar altimeter that is specifically looking straight down, but it is pretty low power. it is also possible your preamp was picking up the EMI from the radar pulser, not the actual radar microwave energy. Back in the old days with magnetrons, these radars generated microsecond-long pulses of 30 kV and 30 A, and the magnetic pulses from the pulser were pretty hard to shield. Not too sure how far that radiates, obviously not as far as the microwave energy, but maybe it could affect circuits

1000 feet away.

Anyway, with the small volume of your detector, the solid angle from a source 1000 feet away is absolutely minute. There have been shipboard tests of remote detection of nuclear weapons. I suspect they used banks of large scintillators, and it was stated they had to count for 30 minutes or more to get a definitive result. But, they could, pick up the signature of the 239 Pu. They would have been detecting the gamma ray spectrum, not sure what your scintillator is designed for. So, your detector would have been lucky to get even ONE COUNT out of a weapon flying overhead.

Jon

Reply to
Jon Elson

It is the Radio Altimeter. It is a continuous-wave radar with sawtooth- sweeped frequency. The received signal is mixed with a sample of the transmit signal and the resulting difference frequency (audio) is measured. The measurement range is up to 2500 - 3000 feet.

--

Tauno Voipio, MSEE, avionics engineer
Reply to
Tauno Voipio

s

(slaps forehead)

Right. In that case I agree with Jon Elson; listen to the weirdnesses.

Mark L. Fergerson

Reply to
alien8752

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