Cherenkov Effect and Radio

[Lauri-CoyoteFrostbite]

I am taking a break from editing a paper on neutrino detection- a subject that is out of my league; but its for a friend, that, for better or worse, trusts my judgement.
What makes it interesting (enuff for me) to be included here is she uses radio frequencies- specifically 220 Mhz . So I'm placing my little diversion here in the Amateur Radio section.

How does radio play into this esoteric arena of subatomic particle physics ? That's where it gets fun.

Its called the Cherenkov Effect.... and while some haven't heard of this, I can bet most reading this have seen pictures of it. Its the blue glow seen beneath the water barrier of 'glowing' nuclear reactors.
And explaining that glow becomes a challenge since what we are seeing is, in effect, a sonic boom- the products of a high energy particles streaking thru a dielectic- in this case water.
In a vacuum, nothing moves faster than a photon of light. But in other mediums, like water, light is slowed by a quarter (to 0.75c)- where as other particles can excced this speed. Without going into the physics, what occurs is a 'sonic wave' front, that as this wave spreads out from the speeding particle, it creates a ever widening wave of frequencies- from ultra violet light-- down into the radio waves. As this front moves, the trailing wave widens and the frequency shifts downward.

So, (very) simply put; detect that and we can begin to understand subatomic particles.

I throw this out to inquisitive minds, but I don't think this will give a new purpose for anyone's 220 xcvr.

Lauri
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[prcguy]

I want to know how to modulate a neutrino so I can make the ultimate DX machine.

 

[dlwtrunked]

...
And explaining that glow becomes a challenge since what we are seeing is, in effect, a sonic boom- the products of a high energy particles streaking thru a dielectric- in this case water.
In a vacuum, nothing moves faster than a photon of light. But in other mediums, like water, light is slowed by a quarter (to 0.75c)- where as other particles can exceed this speed. Without going into the physics, what occurs is a 'sonic wave' front, that as this wave spreads out from the speeding particle, it creates a ever widening wave of frequencies- from ultra violet light-- down into the radio waves...
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I would call it an "photonic boom" and "photonic wave" to distinguish it as being photons in nature rather than sound in nature. Readily seen in fuel storage in water at nuclear plants. I think it is far too weak of signal in the radio spectrum of frequencies to be noted at any distance. You have to be careful as some will misunderstand-some of my best laughs seen in newsgroups have been people who wonder wonder why one cannot hear VLF radio signals with their ears. That one ranks up there with the person who visited a USAF GWEN (Ground-wave Emergency Network, decommissioned a long time ago) station under construction, and saw the ground dug up with them burying wires. He said that must be the antenna for the "underground radio signals" and he wondered what was the purpose for the 299 foot tower. And then once in a Radio Shack in Indiana, PA in 1981, I heard a women ask the clerk if the VHF or UHF antenna should go on top the pole. His answer was the UHF should be on the bottom as UHF being a shorter wavelength than VHF, it could not go as high above the ground. (I could not stop laughing). [For those who need to be told, radio waves and sound waves are completely different things. There first is electromagnetic radiation or photons, and sound waves are compression waves in the atmosphere or other media. Of course a microphone and transmitter can covert sound to modulated radio waves; but still sound waves and radio waves are different things. And regarding ground-wave communication: the 299 ft tower was transmitting signal. He saw the ground-system for that being buried. At lower frequencies, "ground wave" refers to the fact that some of the transmitted radio signal will follow the curvature of the earth--it does not mean it is a signal in the ground.]

While on subject of of such things, many do not know that all objects emit electromagnetic signal due to their temperature (always above absolute zero). This is what makes thermal (or FLIR) cameras possible. A small amount of that is emitted in the lower frequency radio spectrum but is generally not measureable except on the higher microwave end.

 

[RFI-EMI-GUY]

"In a vacuum, nothing moves faster than a photon of light. But in other mediums, like water, light is slowed by a quarter (to 0.75c)- where as other particles can exceed this speed."

This is the stuff that blows my mind.

Now back to current political events straight from the Whitehouse:

"Dopeler Effect
The tendency of stupid ideas to seem smarter when they come at you rapidly"

 

[RFI-EMI-GUY]

When Yosemite Sam threatens to blow someone to "smithereens" , I wonder , is a "smithereen" a subatomic particle?

 

[RFI-EMI-GUY]

I would call it an "photonic boom" and "photonic wave" to distinguish it as being photons in nature rather than sound in nature. Readily seen in fuel storage in water at nuclear plants. I think it is far too weak of signal in the radio spectrum of frequencies to be noted at any distance. You have to be careful as some will misunderstand-some of my best laughs seen in newsgroups have been people who wonder wonder why one cannot hear VLF radio signals with their ears. That one ranks up there with the person who visited a USAF GWEN (Ground-wave Emergency Network, decommissioned a long time ago) station under construction, and saw the ground dug up with them burying wires. He said that must be the antenna for the "underground radio signals" and he wondered what was the purpose for the 299 foot tower. And then once in a Radio Shack in Indiana, PA in 1981, I heard a women ask the clerk if the VHF or UHF antenna should go on top the pole. His answer was the UHF should be on the bottom as UHF being a shorter wavelength than VHF, it could not go as high above the ground. (I could not stop laughing). [For those who need to be told, radio waves and sound waves are completely different things. There first is electromagnetic radiation or photons, and sound waves are compression waves in the atmosphere or other media. Of course a microphone and transmitter can covert sound to modulated radio waves; but still sound waves and radio waves are different things. And regarding ground-wave communication: the 299 ft tower was transmitting signal. He saw the ground-system for that being buried. At lower frequencies, "ground wave" refers to the fact that some of the transmitted radio signal will follow the curvature of the earth--it does not mean it is a signal in the ground.]

While on subject of of such things, many do not know that all objects emit electromagnetic signal due to their temperature (always above absolute zero). This is what makes thermal (or FLIR) cameras possible. A small amount of that is emitted in the lower frequency radio spectrum but is generally not measureable except on the higher microwave end.

A lot of the distinction has to do with the transducer used to couple the signal. An "Ultrasound" starts with a ~ 7.8 MHz RF signal and is converted to an accoustic one using a piezo transducer, and from acoustic back to "RF" using same method. You could replace that transducer with resonant coil and have a small "Radar": system.

 

[dlwtrunked]

A lot of the distinction has to do with the transducer used to couple the signal. An "Ultrasound" starts with a ~ 7.8 MHz RF signal and is converted to an acoustic one using a piezo transducer, and from acoustic back to "RF" using same method. You could replace that transducer with resonant coil and have a small "Radar": system.

A slight comment for accuracy, it was not initially a 7.8 RF signal but a 7.8 MHz electronic signal (moving electrons in wire not RF). Then it became sonic after the transducer. So in that case, it was never intended as a RF signal, although the signal in the wires will generate an RF signal as a side effect and possible interference. So I guess we need to distinquish moving electrons (electronic/electric), moving photons (electromagnetic/radio/electro-optic/etc.) , and moving compression waves (sonic).

 

[RFI-EMI-GUY]

A slight comment for accuracy, it was not initially a 7.8 RF signal but a 7.8 MHz electronic signal (moving electrons in wire not RF). Then it became sonic after the transducer. So in that case, it was never intended as a RF signal, although the signal in the wires will generate an RF signal as a side effect and possible interference. So I guess we need to distinquish moving electrons (electronic/electric), moving photons (electromagnetic/radio/electro-optic/etc.) , and moving compression waves (sonic).

We could throw a fiber-optic link in there for fun as well!

 

[RFI-EMI-GUY]

I want to know how to modulate a neutrino so I can make the ultimate DX machine.

Call the folks at Fermi Lab they can tell you!

 

[AK9R]

As an aside, the ARRL Central Division Director, Kermit Carlson W9XA, is an engineer at Fermilab.

 

[Lauri-CoyoteFrostbite]

Interesting topic, No ?

Without spinning off into some heavy physics, here's a fascinating asides to this. These radio signals are quite powerful- the Cherenkov generated signals in the 220 to 850 MHz will travel detectable thru 1-2 km of ice to receiving antennas.

And modulating a neutrino ?... that's an idea...
...........that is-- once we get beyond even knowing exactly what a neutrino is. They travel clear thru the earth-
Now, think of the DX posibilites there!

I tried to be thought provoking-- Ok Guys- take it from there.... I'm done editing and am going to dinner.

Lauri
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[Kfred]

i had always thought the photons were being difused by the water molecules. the heavier water molecules using up the energy in the photons because of agitation on an atomic level.

 

[RFI-EMI-GUY]

Without spinning off into some heavy physics, here's a fascinating asides to this. These radio signals are quite powerful- the Cherenkov generated signals in the 220 to 850 MHz will travel detectable thru 1-2 km of ice to receiving antennas.

Ice? Are we talking about detection of nuclear subs from top of an ice shelf?

 

[RFI-EMI-GUY]

i had always thought the photons were being difused by the water molecules. the heavier water molecules using up the energy in the photons because of agitation on an atomic level.

I take mine shaken, not stirred.

 

[Lauri-CoyoteFrostbite]

OMG Kfred- do we want to go there ?!

A great question, all the same, but we're now getting into Einstein’s quantum (light) theory and I fear this is really getting esoteric.

Yes. photons can have interactions with other particles such as electrons, (ie: the Compton effect) in which they can either be destroyed or created. An example is when radiation is absorbed or emitted.

We really don't want to get into it, for I am now fearing my introducing this subject was testing the envelope of the forum.
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Oh, but the radio signals thru the ice part ? -- from the Antarctic Muon And Neutrino Detector Array project. My friend is revisiting their field work.
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Lauri

 

[dlwtrunked]

We could throw a fiber-optic link in there for fun as well!

I have seen that done with a radar system.

 

[mikewazowski]

As an aside, the ARRL Central Division Director, Kermit Carlson W9XA, is an engineer at Fermilab.

I used to work at a small open pool research reactor (25MW). The highlight of the tours they gave was standing on the bridge at the far end of the pool which had a good view of the core and the Cherenkov radiation.

 

[Kfred]

this discussion is making the hamster wheel in my head wobble and squeek. if i understand what is being said an energetic broadband frontal wave is being emitted by the spent fuel, (think spark transmitter) this is being fractionated by the water.(tuned circuit) and harmonically divided into multiple frequencies, which would reduce its power output overall but increase its power output in narrow tuned frequencies. need some form of sensors at multiple levels in tank to see what is occurring.

 

[zz0468]

Whatever the physical phenomenon may be, that blue glow would make for a helluva night light by the bed.

"Honey! Look what I found at a garage sale!"

 

[MUTNAV]

The only things I knew about the blue flash are related to nuke incidents, like the first two demon - core events, each accompanied by a blue flash, and the death of those nearby, also the first individual in the darwin awards hall of fame, a Russian that poured radioactive material into a container with "poor geometry", that resulted in a blue flash, then later his death. Is the blue flash from nuclear reactions only, or anything high energy. In NY a large transformer blew up and resulted in a "blue glow" for a few moments.

I really thought the blue glow had been known about, but unexplained. Why is the Chernenkov radiation all in the blue/UV region, shouldn't it have been a little more broadband whiteish light?