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Scintillocartography

ivan.sanchezortega.es

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Re: Scintillocartography

#11

Post by RugnirViking »

4gotunameagain wrote: post #4
0PingWithJesus wrote: post #2

One line in the piece says "Observing the direct effects of radiation, although possible, requires extraordinary circumstances.". While this is mostly true, you can actually observe radiation directly, with your own eyeballs, without any extraordinary methods. Basically all you need is a radioactive source, scintillator and a very dark room. That's how scintillation counting was done back in the day. This sort of dev…

The author probably counts these as indirect effects, as it is the collision of the α particles with zinc sulfide, and not a direct effect of radiation like Cherenkov.

isnt cherenkov also caused by interaction with water molecules?

edit: the article goes into a little more detail and talks about how its due to the different speeds of light in water and vaccuum, and I don't know enough about semantics or physics to say what this means about my original question :)

Re: Scintillocartography

#13

Post by nayuki »

> One of those circumstances is being close to a nuclear reactor submerged in water, which allows Cherenkov radiation to be observed. In layman’s terms: gamma radiation exits the reactor at the speed of light in a vaccuum, but the speed of light in water is lower, and photons have to slow down somehow. The direct, observable effect is that water glows blue.

Almost but not quite. The speed of light is always the speed of light. There's nothing wrong with gamma rays.

It's charged particles such as beta and alpha rays that generate the blue Cherenkov radiation. The writer's link to Wikipedia already reflects that.

Re: Scintillocartography

#14

Post by earthscienceman »

imglorp wrote: post #9
progbits wrote: post #6

I suppose this is as good place as any to ask: What is a good scintillating detector for DIY use? Geiger tubes are relatively easy to find, but all scintillators I could find were "ask for pricing" scientific equipment or some dubious old russian military stock (which I don't want even if it works).

I've had my eye on this one. Not affiliated, just looks fun. https://www.radiacode.com/

Ok. This is very cool.

Re: Scintillocartography

#15

Post by 0PingWithJesus »

RugnirViking wrote: post #11
4gotunameagain wrote: post #4

Earlier quoted context omitted.

The author probably counts these as indirect effects, as it is the collision of the α particles with zinc sulfide, and not a direct effect of radiation like Cherenkov.

isnt cherenkov also caused by interaction with water molecules? edit: the article goes into a little more detail and talks about how its due to the different speeds of light in water and vaccuum, and I don't know enough about semantics or physics to say what this means about my original question :)

It's kinda a complicated question. Cherenkov radiation can be produced in any medium that has index of refraction greater than 1, that's what allows the charged particle radiation to go faster than the light it produces, which ultimate is what causes the Cherenkov light. The process is not reliant on the specific molecular/chemical/whatever properties of the medium, only dependent on the index of refraction. But, the index of refraction in turn comes from polarizabilty and magnetic susceptibility of the medium. Those factors depend on both what atoms & molecules exist in the medium, but also the structure of those molecules. For example, ice and water have the some chemical composition, but slightly different indices of refraction.

Re: Scintillocartography

#16

Post by NextHendrix »

nayuki wrote: post #13

> One of those circumstances is being close to a nuclear reactor submerged in water, which allows Cherenkov radiation to be observed. In layman’s terms: gamma radiation exits the reactor at the speed of light in a vaccuum, but the speed of light in water is lower, and photons have to slow down somehow. The direct, observable effect is that water glows blue. Almost but not quite. The speed of light is always the speed…

The speed of light in a vacuum is always the same, but not through dielectric media such as water or glass. In diamond it is less than half the speed.

Re: Scintillocartography

#17

Post by SiempreViernes »

0PingWithJesus wrote: post #15
RugnirViking wrote: post #11

Earlier quoted context omitted.

isnt cherenkov also caused by interaction with water molecules? edit: the article goes into a little more detail and talks about how its due to the different speeds of light in water and vaccuum, and I don't know enough about semantics or physics to say what this means about my original question :)

It's kinda a complicated question. Cherenkov radiation can be produced in any medium that has index of refraction greater than 1, that's what allows the charged particle radiation to go faster than the light it produces, which ultimate is what causes the Cherenkov light. The process is not reliant on the specific molecular/chemical/whatever properties of the medium, only dependent on the index of refraction. But, the…

Well, for the purposes of observing the Cherenkov light it is fairly important the material is transparent at blue wavelengths :)

Re: Scintillocartography

#18

Post by 0PingWithJesus »

SiempreViernes wrote: post #17
0PingWithJesus wrote: post #15

Earlier quoted context omitted.

It's kinda a complicated question. Cherenkov radiation can be produced in any medium that has index of refraction greater than 1, that's what allows the charged particle radiation to go faster than the light it produces, which ultimate is what causes the Cherenkov light. The process is not reliant on the specific molecular/chemical/whatever properties of the medium, only dependent on the index of refraction. But, the…

Well, for the purposes of observing the Cherenkov light it is fairly important the material is transparent at blue wavelengths :)

To be a bit nit-picky, Cherenkov light typically has a wide spectrum. For water it spans the entire optical range, peaking around 350nm and dying off at longer wavelengths. So you could, for example, put dye in water such that it absorbed more blue light, but you'd still be able to observe some red light from the Cherenkov radiation escaping. But the signal would be much fainter.

Although, one further caveat, changing a materials absorption spectrum will also change it's refractive index as a function of wavelength, which will in turn effect how much Cherenkov light is emitted at each wavelength. So the situation is more complicated still.

Re: Scintillocartography

#19

Post by nayuki »

NextHendrix wrote: post #16
nayuki wrote: post #13

> One of those circumstances is being close to a nuclear reactor submerged in water, which allows Cherenkov radiation to be observed. In layman’s terms: gamma radiation exits the reactor at the speed of light in a vaccuum, but the speed of light in water is lower, and photons have to slow down somehow. The direct, observable effect is that water glows blue. Almost but not quite. The speed of light is always the speed…

The speed of light in a vacuum is always the same, but not through dielectric media such as water or glass. In diamond it is less than half the speed.

You're right, but I knew that. I should've worded my statement in such a way to prevent criticism.

Gamma rays always follow the speed of light in the medium that they travel through, because they are light. They cannot exceed the local speed of light, thus they cannot generate Cherenkov radiation. It must be particles with charge and non-zero mass that are capable of generating Cherenkov radiation.

Re: Scintillocartography

#20

Post by defrost »

imglorp wrote: post #9
progbits wrote: post #6

I suppose this is as good place as any to ask: What is a good scintillating detector for DIY use? Geiger tubes are relatively easy to find, but all scintillators I could find were "ask for pricing" scientific equipment or some dubious old russian military stock (which I don't want even if it works).

I've had my eye on this one. Not affiliated, just looks fun. https://www.radiacode.com/

That is a fantastic pocket sized super fun gadget.

A relevant spec sheet to compare against what was outlined above is:

https://www.gammadata.se/assets/Uploads/CsITl-and-Na-data-sh...

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