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Results tagged with protons
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user 43351
A proton is a positively charged particle which is generally considered to be a composite particle comprising of three quarks interacting through the strong force (e.g. in the standard model.)
11
votes
Is there a term for electron capture outside the nucleus?
It occurs between free protons and electrons in the cores of collapsing stars immediately prior to a supernova and as an equilibrium process in the neutron fluid region of a neutron star. …
- 136k
2
votes
Can neutrons be synthesized purely from protons and electrons?
"Free" electrons and protons can combine to form neutrons (and electron neutrinos) through weak interactions. … This reaction, between free protons and electrons might occur in neutron stars. …
- 136k
3
votes
Accepted
Charged particle singularity
If you take two protons, they have a mass of about $3.34\times10^{-27}$ kg.
The "Schwarzschild radius" of a two-proton black hole is given by $2GM/c^2 = 5 \times 10^{-54}$ m ! … i.e. you have to get the protons closer together than this. …
- 136k
7
votes
Accepted
How big of a neutron star would be needed to form a quark star inside of it?
A quark star may or may not be possible - as the wikipedia page you refer to says - they are "hypothetical".
As the mass of a neutron star increases, generally speaking, it become smaller and the ce …
- 136k
27
votes
Accepted
What is the reason for the shift in balance between neutrons and protons in the early universe?
$(m_n - m_p)c^2 = 1.29$ MeV. (2) The total number of neutrons plus protons (essentially the only baryons present) is a constant. … Equal numbers of neutrons and protons.
As the universe expands and cools to less than a few MeV (a few $10^{10}$ K) two things happen. …
- 136k
2
votes
Why the Binding Energies of Neutron and Proton are different?
The strong nuclear force felt by neutrons and protons is approximately the same, but only the proton feels the repulsive force from the other protons in the nucleus. …
- 136k
1
vote
Why are there (roughly, at least) equal numbers of electrons and protons in the universe, de...
The mass ratio is only relevant in so far as determining things like when and where the protons and electrons are produced and that the electron, being the lightest charged lepton, is the "ground state …
- 136k
6
votes
What makes the number of neutrons the number of proton similar?
You can think of the protons and neutrons in a nucleus as consisting of two fermion gases (neutrons and protons) made of indistinguishable particles. … The energy levels are roughly similar for the neutrons and protons because the strong nuclear force is blind to whether neutrons are protons are involved and the differences are smaller than the gap between …
- 136k
2
votes
How is the speed of nucleons in the nucleus measured?
An even simpler variant of Ben's answer. Use the uncertainty principle. $\Delta p\ \Delta x \geq \hbar/2$.
If a nucleon is trapped in a box of order $\Delta x \sim 1.2\times 10^{-15} A^{1/3}$ m, wher …
- 136k
0
votes
How do protons fuse in the sun?
The Coulomb energy of two protons separated by $1.5\times 10^{-15}$ m is about 1 MeV. The modulus of the (negative) diproton binding energy is less than this. … Likewise, it is then very easy for the diproton to decay back into two protons, or very rarely, into a bound deuteron whilst ejecting a positron. …
- 136k