alpha coincidence experiment

[Theoretical]

So I've been exchanging emails with Eric Reiter about his alpha coincidence experiment. Basically he claims to emit alpha particles toward a gold foil. The foil causes the particle to either reflect left or travel forward, detector A or B. But he claims a single alpha particle travels in both directions.

 

He has a slab of Am-241 taken from a smoke detector. Not sure on the thickness. First off he claims two alpha particles are emitted from each nucleus traveling 180° from each other in both directions. Alphas from Am-241 have extremely low penetration depth. So it seems the alphas emit mostly from the nucleus of atoms near the surface of the material. What's the likelihood of Eric detecting two alphas traveling in opposite directions? Doesn't it seem like he's detecting gamma rays?

 

As you can see in the following image, Eric claims to emit alphas toward a gold foil, which he claims splits the alpha particle into two half alpha particles. Yes, that's correct, two alphas that are intact. I guess one could call them sub-alpha particles.

 

http://unquantum.net/wp-content/uploads/2012/10/alpha-split-demo-31.jpg

 

According to my calculations there's insufficient energy to split the alpha. He says his alphas are emitted at 5.5MeV, maybe more like 5.2MeV. That's roughly one fourth the energy to remove a proton from the alpha particle.

 

What about angular energy? The alpha is spinning as it's ejected. Or thermal energy? I think the probability of those being enough to split the alpha particle is low.

 

At first I thought he was seeing a weak stimulated alpha emission. But now I have to wonder if he's just detecting gamma rays.

 

Any thoughts?

 

BTW, the mention of Eric measuring two alpha particles being emitted 180° apart from each other simultaneously is another experiment Eric did. That's not the alpha coincidence experiment.

Edited December 8, 2015 by Theoretical

[swansont]

So I've been exchanging emails with Eric Reiter about his alpha coincidence experiment. Basically he claims to emit alpha particles toward a gold foil. The foil causes the particle to either reflect left or travel forward, detector A or B. But he claims a single alpha particle travels in both directions.

 

He has a slab of Am-241 taken from a smoke detector. Not sure on the thickness. First off he claims two alpha particles are emitted from each nucleus traveling 180° from each other in both directions. Alphas from Am-241 have extremely low penetration depth. So it seems the alphas emit mostly from the nucleus of atoms near the surface of the material. What's the likelihood of Eric detecting two alphas traveling in opposite directions? Doesn't it seem like he's detecting gamma rays?

 

As you can see in the following image, Eric claims to emit alphas toward a gold foil, which he claims splits the alpha particle into two half alpha particles. Yes, that's correct, two alphas that are intact. I guess one could call them sub-alpha particles.

 

http://unquantum.net/wp-content/uploads/2012/10/alpha-split-demo-31.jpg

There's not enough information presented to critique this.

 

What about angular energy? The alpha is spinning as it's ejected.

It is?

 

At first I thought he was seeing a weak stimulated alpha emission. But now I have to wonder if he's just detecting gamma rays.

 

Any thoughts?

Where would the gammas be coming from?

 

How is he doing the detection? There may be schemes that are not sensitive to gammas. It's tough to give thoughts when you present no details.

[Theoretical]

Unfortunately I don't have much more information either. As the image shows he's using a Am-241. Am-241 emits low energy gamma. You should know that, rather than attacking me.

[Strange]

I had a quick skim of his website. Unusually, he does seem to have documented what he has done in great detail and taken some care in experimental methodology. I can think of a few obvious things to check but this isn't my area of expertise (*) and I don't have time to go through it all.

 

(*) "What is?" I hear you ask.

[swansont]

Asking for additional detail is not an attack. Since an interaction with the gold is being claimed, that does not preclude the possibility of gammas originating there. You should know that, rather than having an attitude.

[Theoretical]

Let's not confuse his gamma coincidence experiments. But yes he's probably using the same scintillation counters to detect alpha particles.

[snip] Since an interaction with the gold is being claimed, that does not preclude the possibility of gammas originating there. You should know that, rather than having an attitude.

That's more like it

[swansont]

Questions that come to mind are whether the detector can resolve the energy of the particles, and if it's sensitive to electrons. I suspect that some fairly high energy electrons get kicked out of the foil when an alpha comes tearing through. Having looked at relevant section of the FQXI paper, it seems perhaps not. "Both SCA LL settings were at 1/3 of the characteristic a pulse-height " That means it should be insensitive to a 60 keV gamma, too.

 

He did a two-hour control test, but the coincidences in the main experiment the coincidences were at less than one per day (~10^-5/sec; did he really do this experiment for two months or so?), so that's not conclusive. The control was in a different geometry — 90 degrees vs back-to-back. He doesn't label his graphs well, so I don't really know what figures 7 and 8 are showing.

[Theoretical]

Thanks. It could be insensitive to low energy gammas, but not 100%. His coincidences occur at such low rates, which seems to indicate it's gamma, or energetic electrons as you mentioned. I'm not sure what gamma energy range the alpha would produce colliding with the gold. I'd imagine there's an appreciable probability of it being at least a few MeV, no?

Braking radiation.

[swansont]

Thanks. It could be insensitive to low energy gammas, but not 100%. His coincidences occur at such low rates, which seems to indicate it's gamma, or energetic electrons as you mentioned. I'm not sure what gamma energy range the alpha would produce colliding with the gold. I'd imagine there's an appreciable probability of it being at least a few MeV, no?

Braking radiation.

 

 

I don't understand why low rates indicates gamma.

 

If the discriminator is set to 1/3 of the alpha energy, then it will filter out anything below ~1.8 MeV. But that might not hold for particles that aren't alphas. I don't know the details of that detector, but since alphas deposit their energy in such a small volume, there's a possibility the detector would be less sensitive to electrons and gammas.

[Sensei]

Any thoughts?

 

Ask him to repeat experiment inside of Cloud Chamber, so traces will be visible and record able by digital camera..

 

Then he should use electric field, or magnetic field to learn charge of emitted particles.

This way he will know whether he has alpha, beta, or some neutral particle like gamma.

Trace will be bend accordingly to charge, and mass of particle.

 

He should use mass spectrometer on Gold foil to see whether he has Au-197. Before and after using on it alphas.

Did he use 100% 24 carat Gold?

If he used 14 carat (58.3% Au), or 18 carat (75%) Gold, it's contaminated by secondary metals like Silver, Copper etc.

24 carat can be little contaminated as well.

He should use mass spectrometer on it anyway though.

 

Hitting contamination by alpha could influence results.

 

If mass spectrometer will tell him, it's contaminated with Silver, he should check how is behaving Silver foil instead of Gold foil. If contaminated by Copper, try Copper foil instead.

Then melt Gold and Silver, or Gold and Copper, together, and make various foils with different percentages of both.

And check them to see which one behaves like this original Gold foil. Whether these additional alphas are appearing more often while using alloy.

 

 

Decay energy of Am-241 is 5.64 MeV.

Part of it takes Np-237, but still it's quite a lot for alpha particle kinetic energy.

Edited December 8, 2015 by Sensei

[Theoretical]

I don't understand why low rates indicates gamma.

 

If the discriminator is set to 1/3 of the alpha energy, then it will filter out anything below ~1.8 MeV. But that might not hold for particles that aren't alphas. I don't know the details of that detector, but since alphas deposit their energy in such a small volume, there's a possibility the detector would be less sensitive to electrons and gammas.

I don't put that much trust in PMTs. Set your discriminator to 2MeV, place a strong 1MeV source near the scintillator/PMT. I'm betting you'll see a noticeable slight increase in count rate.

 

 

 

Ask him to repeat experiment inside of Cloud Chamber, so traces will be visible and record able by digital camera..

 

Then he should use electric field, or magnetic field to learn charge of emitted particles.

This way he will know whether he has alpha, beta, or some neutral particle like gamma.

Trace will be bend accordingly to charge, and mass of particle.

 

He should use mass spectrometer on Gold foil to see whether he has Au-197. Before and after using on it alphas.

Did he use 100% 24 carat Gold?

If he used 14 carat (58.3% Au), or 18 carat (75%) Gold, it's contaminated by secondary metals like Silver, Copper etc.

24 carat can be little contaminated as well.

He should use mass spectrometer on it anyway though.

 

Hitting contamination by alpha could influence results.

 

If mass spectrometer will tell him, it's contaminated with Silver, he should check how is behaving Silver foil instead of Gold foil. If contaminated by Copper, try Copper foil instead.

Then melt Gold and Silver, or Gold and Copper, together, and make various foils with different percentages of both.

And check them to see which one behaves like this original Gold foil. Whether these additional alphas are appearing more often while using alloy.

 

 

Decay energy of Am-241 is 5.64 MeV.

Part of it takes Np-237, but still it's quite a lot for alpha particle kinetic energy.

Great method. We already know from experimentation that alpha particles don't become two alpha particles in cloud chambers, which is basically the idea he's proposing. I was just curious how he's getting the results. Edited December 8, 2015 by Theoretical