Why doesn't a dineutron system form a bound state?

[zahero_2007]

Why doesn't a dineutron system form a bound state?

Why doesn't 2 neutrons with one spin up and the other spin down form a bound state but a neutron and proton with both spin up or down form a bound state

 

[zahero_2007]

Another question , Is the binding energy per nucleon (assuming A is small enough) stronger for a p-n nucleus with one spin up and the other spin down than a p-n nucleus with both spin up or down?

 

[AdrianTheRock]

Of the possible bound states for two nucleons, the ground state is ₁H², so a state of two neutrons would decay to this via the weak force.

 

[zahero_2007]

Ok , but Why doesn't the 2 neutrons form a ground state?

 

[tom.stoer]

Because of the spin and isospin symmetry properties of the nucleon-nucleon force.

If I remember correctly wer had this discussion here a coupleof times; please search for "dineutron" or something like that.