binbagsss
Jan29-12, 01:13 PM
I am currently reading E=Mc^2 and have a quick question regarding some of the nuclear fusion they describe that takes place in stars:
When proton fusion occurs, one of the protons decays into a neutron + positron + neutrino – due to the weak interaction.
And the proton and neutron , acted together on by the strong nuclear force,+ the positron and neutrino formed have a lower mass than the intial 2 protons, releasing Energy.
So from this, I conclude that 4 protons are required to form 1He with 2 neutrons and 2 protons.
Then, in terms of the nuclear fusion which occurs in stars, the book says that:
2 HE fuse together to form BE-8 – 4 neutrons and 4 protons – this is where I do not follow.
From the above I would then assume that together 2HE would fuse into 2 protons + 2 neutrons (from the protons and due to the weak interaction), + another 4 neutrons, giving 6 neutrons, 2 proton rather than 4 protons and 4 neutrons.
So, my question is, how does the weak interaction act?
- could it be the case that 2 of the neutrons undergo decay themselves into a proton, electron + antineutrino
or
- could no quark flavour change occur , (so proton fusion occurs without any weak interaction interference – is this possible and so that only sometimes when proton fusion occurs, does the weak interaction interfere) – book states “ ...Not always, but some of the time when two protons come close together, a proton turns intself into a neutron..”
Thank alot :smile:
When proton fusion occurs, one of the protons decays into a neutron + positron + neutrino – due to the weak interaction.
And the proton and neutron , acted together on by the strong nuclear force,+ the positron and neutrino formed have a lower mass than the intial 2 protons, releasing Energy.
So from this, I conclude that 4 protons are required to form 1He with 2 neutrons and 2 protons.
Then, in terms of the nuclear fusion which occurs in stars, the book says that:
2 HE fuse together to form BE-8 – 4 neutrons and 4 protons – this is where I do not follow.
From the above I would then assume that together 2HE would fuse into 2 protons + 2 neutrons (from the protons and due to the weak interaction), + another 4 neutrons, giving 6 neutrons, 2 proton rather than 4 protons and 4 neutrons.
So, my question is, how does the weak interaction act?
- could it be the case that 2 of the neutrons undergo decay themselves into a proton, electron + antineutrino
or
- could no quark flavour change occur , (so proton fusion occurs without any weak interaction interference – is this possible and so that only sometimes when proton fusion occurs, does the weak interaction interfere) – book states “ ...Not always, but some of the time when two protons come close together, a proton turns intself into a neutron..”
Thank alot :smile: