I Can you tell the difference between two neutrons in an alpha particle?

[wasong]

TL;DR Summary

Can you tell the difference between two neutrons in an alpha particle?

Can you tell the difference between two neutrons in an alpha particle? In one alpha particle, we know that the sum of the spins of two neutrons is zero. Can a neutron with upspin and a neutron with downspin be distinguished from each other? Or can't you tell because it's superimposed?

 

[vanhees71]

Neutrons are indistinguishable fermions. All you can say is that when measuring the spins of the two neutrons you find with some probability each of the 4 possible outcomes, given by the prepared state, in this case a bound state of 2 protons and 2 neutrons within a 4He nucleus.

Where did you get the information about the sum of the spins of the two neutrons being zero?

 

[andresB]

Where did you get the information about the sum of the spins of the two neutrons being zero?

My knowledge of nuclear physics is almost zero, but I guess that if the two neutrons are understood to be in the ground state of a potential well, then Pauli's principle demands that they are in a singlet state.

 

[vanhees71]

But it's a bound state of four particles not two particles in a potential well.

 

[andresB]

But it's a bound state of four particles not two particles in a potential well.

That's how nuclei are modeled, particles within a potential well, like Wood-Saxon. Besides, the total wavefunction is antisymmetric for the proton variable and antisymmetric for the neutron variables, but there are no antisymmetry demands between one neutron and one proton.

http://www.personal.soton.ac.uk/ab1u06/teaching/phys3002/course/05_shell.pdf

Anyways, a better answer requires someone that actually knows nuclear physics. I'm curious to know if my guess is correct or not.

 

[Vanadium 50]

I'm curious to know if my guess is correct or not.

Not really. Alphas are not ordinary nuclei, since every nucleon is in the 1S state. (Indeed, by some measures, an alpha is smaller than a proton).

The model of one particle in the potential well created by the other three is not very good for alphas. Two and two is even worse.

And guessing tends to confuse the OP more than clarifying. It's better to ask on another thread.