[alancalverd]

Getting similar numbers may indicate some correlation. But it can also be coincident.

One of James Bond's more memorable statements:
"Once is happenstance, twice is coincidence. Three times is enemy action."
I think 10⁹, exactly as predicted, several times a day in several different laboratories, suggests a law of physics.
But who really knows if the sun will rise tomorrow?

I can't see how an aluminum capacitor can have any effect on the direction of emission of an annihilation photon.

[hamdani yusuf (OP)]

One of James Bond's more memorable statements:
"Once is happenstance, twice is coincidence. Three times is enemy action."
I think 109, exactly as predicted, several times a day in several different laboratories, suggests a law of physics.
But who really knows if the sun will rise tomorrow?

If you measure speed of light in vacuum a trillion times a day, you will also get the same number as coordinate of the great pyramid of Giza.

[hamdani yusuf (OP)]

I imagine an aluminum plate 100x100 mm, smeared with water containing ¹⁵O,  and another aluminum plate 100x100 mm on top of it, like a capacitor.



https://en.wikipedia.org/wiki/List_of_PET_radiotracers
Will the gamma ray still generated at random direction? Or they will be more likely directed normal to the plates?
Or the contrary, more gamma ray directed perpendicular to the normal?

You do know that water conducts electricity, don't you?
So your idea is impossible.
Why did you propose it?

Pure water is not a good electrical conductor.
I showed the picture of a capacitor to illustrate the shape of the proposed apparatus, not that it will work as a capacitor.

[hamdani yusuf (OP)]

I can't see how an aluminum capacitor can have any effect on the direction of emission of an annihilation photon.

The positrons are supposedly produced by ¹⁵O in the radioactive water between the plates in random direction. Because the water is shaped as 2 dimensional surface, the effective direction of positrons hitting electrons would be normal to the plates.
At least the experiment will show if the trajectory of the positron before hitting the electron has any effect on the direction of the gamma rays they emmit.
Let's say a positron moves in positive x direction before hitting a stationary electron. Will the gamma ray produced by the collision equally likely to go in x direction as any other direction? Will it be more likely? Or less likely instead?
What's the prediction of existing model?

[Bored chemist]

Pure water is not a good electrical conductor.

Yes it is, in this context.
Saying things that are not true does not make you look good.
Nor does calling me either a liar or a fool.

Without your pointless set-up the positronium decays somewhere in the water.
It's very small; roughly twice the size of a hydrogen atom.
So, it is small enough to "see" the electric field of the water molecule(s) near it.

And that is a very strong field.

So the voltage gradient- the field- you could get across your capacitor would need to be much bigger (or the local field produced by the water molecules would dominate any effect).

But if you put a water molecule in a field  which is much bigger then that produced by the water dipole, the molecule will be torn apart- it will no longer be an insulator.

So, don't try to tell me that water is a poor conductor.
In your experiment it would be a plasma with a negative incremental resistance.

[Bored chemist]

If you measure speed of light in vacuum a trillion times a day, you will also get the same number as coordinate of the great pyramid of Giza.

No, actually, you don't.
The number is close, but no more correct than a bunch of other lines of latitude which go through the object.

Also, the point you made is irrelevant.
Measuring the same thing many times does not tell you much.
To be any use, you would need to measure other pyramids and find some connection there as well.

Whereas, as Alan has pointed out, billions of particles in thousands of hospitals in dozens of countries all agree,
The chances of that happening make the national lottery look like a certainty.

[alancalverd]

If you measure speed of light in vacuum a trillion times a day, you will also get the same number as coordinate of the great pyramid of Giza.

This proving that the Egyptians invented SI measurements (it was actually the French revolutionaries), sexagesimal angular measurements (it was actually the Babylonians) and decimal GPS coordinates (actually the US military).

[hamdani yusuf (OP)]

Yes it is, in this context.
Saying things that are not true does not make you look good.
Nor does calling me either a liar or a fool.

What context? I wasn't trying to make a capacitor.
It looks like you are being too sensitive.

[hamdani yusuf (OP)]

Whereas, as Alan has pointed out, billions of particles in thousands of hospitals in dozens of countries all agree,
The chances of that happening make the national lottery look like a certainty.

What do they agree upon? The gamma ray frequency?

[hamdani yusuf (OP)]

If you measure speed of light in vacuum a trillion times a day, you will also get the same number as coordinate of the great pyramid of Giza.

This proving that the Egyptians invented SI measurements (it was actually the French revolutionaries), sexagesimal angular measurements (it was actually the Babylonians) and decimal GPS coordinates (actually the US military).

No, it's not. And that's the point.

[alancalverd]

What do they agree upon? The gamma ray frequency?

The gamma energy, 180 degree coincidence, and the fact that it only happens when a positron emitter is present. And something to do with Einstein and Planck, way beyond my pay grade.

[Bored chemist]

What do they agree upon?

That's often the wrong question.
You don't make much progress in science by looking at what agrees.

The interesting question is "What do they disagree on?".

And the answer so far is "nothing".
All the experiments give the expected outcomes.

So this is not a field where you can improve the theories.

[Bored chemist]

Yes it is, in this context.
Saying things that are not true does not make you look good.
Nor does calling me either a liar or a fool.

What context? I wasn't trying to make a capacitor.
It looks like you are being too sensitive.

No.
You called it "like a capacitor." If I wanted to consider it as a capacitor I would just quote the time constant; I think it's about 130µseconds- that's how long you have to do your experiment before the charge leaks away.

In the context of the experiment you propose...
I am simply pointing out that in order for the field between your two plates to make a significant  difference to the positron  behaviour, it would have to be stronger than the field in which the positrons are already present.
But that field is the field  produced by the dipoles of the water molecules.
And if you put water in a much stronger field than that, you pull the water apart.

Saying the water isn't a good conductor is simply not true in those conditions is it?.

[Bored chemist]

If you measure speed of light in vacuum a trillion times a day, you will also get the same number as coordinate of the great pyramid of Giza.

This proving that the Egyptians invented SI measurements (it was actually the French revolutionaries), sexagesimal angular measurements (it was actually the Babylonians) and decimal GPS coordinates (actually the US military).

No, it's not. And that's the point.

Nobody says that coincidences do not happen.
But you are saying that all the PET scan images are a set of about 10^19 coincidences.
That's stupidly lucky, isn't it?

[hamdani yusuf (OP)]

You called it "like a capacitor." If I wanted to consider it as a capacitor I would just quote the time constant; I think it's about 130µseconds- that's how long you have to do your experiment before the charge leaks away.

If I called it like a sandwich, perhaps you'll complain that it's not edible.

[hamdani yusuf (OP)]

In the context of the experiment you propose...
I am simply pointing out that in order for the field between your two plates to make a significant  difference to the positron  behaviour, it would have to be stronger than the field in which the positrons are already present.
But that field is the field  produced by the dipoles of the water molecules.
And if you put water in a much stronger field than that, you pull the water apart.

The purpose of the metal plates are to provide the shape of 2 dimensional surface for positron sources. Nothing more. Because the shape and composition of human tissues are generally too complex for experiments of basic science.

[hamdani yusuf (OP)]

Nobody says that coincidences do not happen.
But you are saying that all the PET scan images are a set of about 10^19 coincidences.
That's stupidly lucky, isn't it?

What actually those PET scan images agree on?

[alancalverd]

The PET images tell you the distribution of the positron-emitting pharmaceutical in the patient's body. This depends on patient physiology. The most common applications use a compound that is avidly absorbed by cancerous  tissue. The PET image locates the "hot" organ in space, and that is then correlated with  a CT or MRI image to identify the particular anatomy.

The time sequence of PET activity can also tell you about the metabolic rates of various organs.

The basic science is all sorted out long before anyone injects stuff into a patient!

[Bored chemist]

Nobody says that coincidences do not happen.
But you are saying that all the PET scan images are a set of about 10^19 coincidences.
That's stupidly lucky, isn't it?

What actually those PET scan images agree on?

Where the stuff is in the body.

[Bored chemist]

In the context of the experiment you propose...
I am simply pointing out that in order for the field between your two plates to make a significant  difference to the positron  behaviour, it would have to be stronger than the field in which the positrons are already present.
But that field is the field  produced by the dipoles of the water molecules.
And if you put water in a much stronger field than that, you pull the water apart.

The purpose of the metal plates are to provide the shape of 2 dimensional surface for positron sources. Nothing more. Because the shape and composition of human tissues are generally too complex for experiments of basic science.

I apologise; I assumed you were planning to do something useful/ interesting like put a voltage across the plates. (Though , as I said, that would be impossible, if you wanted a strong enough field to make any difference)

Without such a voltage, the positrons obviously have no way of knowing that there is an aluminium plate a very long way away from where they are, and so their gamma ray emissions will not be affected by it.
Why did you think a distant metal plate would affect the process?