Any real life demonstrations of radioactive decay?

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I'm skeptical about a some things in physics as some things are hard to understand, or I need to see proof to believe it. I find that for physics, it helps a lot to see a real life demonstration (video) of what's being explained. I understand the whole radioactive decay thing, but I have not been able to find a single video which actually shows an element decaying. Why is this? Does radioactive decay actually exist or is it a theory? Surely it cant be hard to put an element with a half life a a few days/weeks in front of a camera to show it's decay. If radioactive decay is occuring in an element, then how does the element ever actually form into a significant amount if it's constantly decaying?
 
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  • #2
ZapperZ
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First of all, what exact is it that you are expecting to see in a radioactive decay? A visual display of the disintegration? If we can SEE radioactivity taking place with just putting it in front of a video camera, we won't need a Geiger counter or other sophisticated detection devices!

Secondly, an experiment on radioactivity with short half-life is actually a common experiment in undergraduate intro physics! Look at this physics lab, for example:

http://electron6.phys.utk.edu/phys250/Laboratories/radioactive_halflife_of_ba.htm

So no, it is NOT that difficult to demonstrate this. It is, however, not what you were expecting to "see".

BTW, the laws written in our books are very difficult for many people to understand and comprehend, which is why we often need lawyers. Using your "principle", are you also "skeptical" of their existence?

Zz.
 
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BTW, the laws written in our books are very difficult for many people to understand and comprehend, which is why we often need lawyers. Using your "principle", are you also "skeptical" of their existence?

Zz.
No I am not.

Thanks for the other part of your answer.

EDIT: "If we can SEE radioactivity taking place with just putting it in front of a video camera, we won't need a Geiger counter or other sophisticated detection devices!"

I think you might have misinterpreted this part of my post. What I meant, was to just record a video of the decay to show students, not using a camera to measure the amount of decay (this is what you interpreted i think?)
 
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  • #4
sophiecentaur
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This link (and you can search for many others) tells you about a demonstration of the half life of protactinium. It's a popular School Demo.
It involves using a Uranium salt that is continuously transmuting into the product Protactinium. You use a chemical process to separate the protactinium, which has a short half life (about half a minute iirc) from the uranium. You put the Protactinium in front of the GM tube and screen off the rest of the Uranium. The decay is fast enough to show it on a video of the counter screen.
But remember - health and safety rules here, if you want to show the demo to students.
 
  • #5
Drakkith
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I'd guess a large problem is that it is very difficult to gather enough of a fast decaying element for the decay to be visually noticeable on a camera over a few days/weeks.
 
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I think you might have misinterpreted this part of my post. What I meant, was to just record a video of the decay to show students, not using a camera to measure the amount of decay (this is what you interpreted i think?)
Is it that maybe you expect the radioactive sample to disappear due to radioactive decay? Or shrink visibly in size? Is this what you mean to see in a video?

Oh, I see that Drakkith had the same idea.
 
  • #7
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I'm skeptical about a some things in physics as some things are hard to understand, or I need to see proof to believe it. I find that for physics, it helps a lot to see a real life demonstration (video) of what's being explained. I understand the whole radioactive decay thing, but I have not been able to find a single video which actually shows an element decaying. Why is this? Does radioactive decay actually exist or is it a theory? Surely it cant be hard to put an element with a half life a a few days/weeks in front of a camera to show it's decay. If radioactive decay is occuring in an element, then how does the element ever actually form into a significant amount if it's constantly decaying?
Google PET imaging or SPECT imaging. We take images of stuff decaying thousands of times every day around the world for medical purposes.
 
  • #8
SteamKing
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Does radioactive decay actually exist or is it a theory?
It obviously exists, otherwise nuclear power would be a hoax, and the nuclear reactors melting down in the wake of the tsunami at Fukushima, Japan would just be another scam perpetrated by those wily Japanese. Madame Curie and her husband would be two more involved in the conspiracy. Not to mention the Nuclear Regulatory Commission. The list of possible conspirators is endless.

Surely it cant be hard to put an element with a half life a a few days/weeks in front of a camera to show it's decay.
Elements with that level of radioactivity are difficult to handle. A lot of precautions need to be taken to show what exactly?

If radioactive decay is occuring in an element, then how does the element ever actually form into a significant amount if it's constantly decaying?
Radioactive elements are decaying every day in nature. The elements with long half-lives, like Uranium-238 (HL = 4.5 billion years) will stick around longer than those with shorter half lives. Protactinium-231 (HL = 32,000 years) is found in trace amounts, but other isotopes of Protactinium, which have half-lives of a few days, have disappeared from nature almost completely.

At one time, minute amounts of radium were added to paint used to paint the dials of clocks and other instruments so they could be read in the dark. Because of the radiation poisoning hazard, radium paint was phased out and replaced by phosphorescent paint. The factories which produced or used such paint became radiation hazards which had to be cleaned up decades after they went out of business.

You can see the glow of a radium clock face in this article:

http://en.wikipedia.org/wiki/Radium_dials

I'm sure if you scour the web, you'll find plenty of other images.
 
  • #9
sophiecentaur
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I

Radioactive elements are decaying every day in nature. The elements with long half-lives, like Uranium-238 (HL = 4.5 billion years) will stick around longer than those with shorter half lives. Protactinium-231 (HL = 32,000 years) is found in trace amounts, but other isotopes of Protactinium, which have half-lives of a few days, have disappeared from nature almost completely.
Many short lived isotopes are being produced continually by the decay process of other, long lived isotopes. Protactinium is always with us and it only needs to be chemically (or physically) separated from its Uranium generator isotope for it to observe its half life.
It's the same with atmospheric Carbon 14, for a different reason.
It isn't a "hoax" about protactinium, either. :wink:
 
  • #10
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I think some of the nicest visual evidence comes from looking at the tracks of radioactive particles. Try googling: [MarieCurie.biz]cloudchamber. A simple cloud chamber is used which shows the tracks of alpha particles as vapour trails. This particular design of chamber was used by UK schools following the Nuffield work scheme.
 
  • #11
CWatters
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What I meant, was to just record a video of the decay to show students, not using a camera to measure the amount of decay (this is what you interpreted i think?)
Perhaps this one..
 
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  • #12
QuantumPion
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  • #13
sophiecentaur
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How about a cloud chamber? http://youtu.be/pewTySxfTQk?t=3m10s
That will show the emissions from a radioactive source but that source will be an isotope with an very long half life. That means that you will not see any actual decay in the number of vapour trails during a feasible time of experiment. The OP wants to see decay at work, imo.
 
  • #15
sophiecentaur
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As I said before, Google PET or SPECT imaging. We image radioactive decay all the time. Furthermore, a lot of PET tracers have half lives of just seconds or minutes.
 
  • #17
sophiecentaur
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As I said before, Google PET or SPECT imaging. We image radioactive decay all the time. Furthermore, a lot of PET tracers have half lives of just seconds or minutes.
The OP mentions Half Life as an important factor. Afaik, your medical imaging just uses emissions. The isotopes used may have short half lives but does the imaging show this? Yes, the relatively short half life makes it safe as a diagnostic tool but that connection is a bit subtle for a demo for students. To show Half Life in action, you need times in the order of a few minutes. Are there any such isotopes used in medical imaging?

Why are people trying to reinvent the wheel here? There are a number of excellent demonstration that you can buy off the shelf.
 
  • #18
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The isotopes used may have short half lives but does the imaging show this? Yes, the relatively short half life makes it safe as a diagnostic tool but that connection is a bit subtle for a demo for students. To show Half Life in action, you need times in the order of a few minutes. Are there any such isotopes used in medical imaging?
Yes, definitely.
 
  • #19
sophiecentaur
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Yes, definitely.
Is this so that you scan actually study the rates of decay or to make the procedure more safe for the patient? (i.e. so that dose has dropped off by the next day.)

I can't think what the half life of a particular isotope can tell you about a biological system. (It can't be affected by the patient's system. Is it very subtle?
 
  • #20
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Is this so that you scan actually study the rates of decay or to make the procedure more safe for the patient? (i.e. so that dose has dropped off by the next day.)

I can't think what the half life of a particular isotope can tell you about a biological system. (It can't be affected by the patient's system. Is it very subtle?
The activity experienced by the patient depends on properties of the isotope itself, such as its half life and properties of various bodily systems such as the excretory system. I think the term "biological half life" is used.
 
  • #21
sophiecentaur
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Afaik, the term biological half-life describes the combination of nuclear decay rate and the rate of excretion by the body of the nuclide. The nuclear activity doesn't have a chemical effect in diagnostic procedures, ifaik (except for the ionising damage to the cells). In radiotherapy, the 'damage' is on purpose and the biological half-life will be one factor that affects the total dose at the target sites.

This is all interesting and totally correct stuff but, again, how does this help the poor guy who just wants a suitable lab demo for his students?
 

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