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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.)
116
votes
Why can atoms only gain or lose electrons and not protons?
It’s not that protons can’t be transferred. It’s just that if we lived in a place where proton transfer was common, we would have a very different perspective on chemistry. …
108
votes
Accepted
How do we know neutrons have no charge?
Free neutrons in flight are not deflected by electric fields. Objects which are not deflected by electric fields are electrically neutral.
The energy of the strong proton-neutron interaction varies …
41
votes
Why does this quiz question say that protons and electrons do not combine to form neutrons?
When the neutron star forms, most of the protons and electrons combine together to form neutrons
This is mostly correct. … The neutrino is an uncharged, very low-mass electron-like particle, in the same way that neutrons and protons are different charge states of the same sort of particle. …
37
votes
Accepted
Are there individual protons and neutrons in a nucleus?
Anything that produces a fragment of a nucleus could be interpreted in either of two ways: a certain number of protons and neutrons broke off of the clump, or the single particle divided into separate … The popular science material always talks about the number of protons and neutrons in a nucleus, but I've always wondered if that's a real thing nuclear physicists believe or if it is just a convenient …
33
votes
Are some protons more massive than others due to spinning at a different rate or being in a ...
Protons are indistinguishable particles; they all have the same mass, exactly. …
10
votes
Do physicists use particle "energy" to refer to kinetic energy?
Yes, in this case what's meant by "energy" is the kinetic energy $K = (\gamma-1)mc^2$ that the incident particle can transfer to the target system. As you point out, it wouldn't make sense to talk ab …
10
votes
Accepted
A proton's weak charge is .0719. Is this dimensionless? A ratio?
You haven't linked to any of the articles that you've read, but the value that you've quoted seems to come from this Nature paper that was published this week.
Note that the news there is the precisio …
8
votes
Accepted
What is the ratio of gluons to baryons?
I asked a question very much like this several years ago (in person, not online, but someone else asked it here): "what's the baryon asymmetry of the proton?"
Thinking, of course, about the three vale …
5
votes
Accepted
Why can't we harness the energy from neutron + protium = deuteron reaction?
Most stable nuclei have a "neutron separation energy" of eight or ten MeV --- that's the minimum cost to produce a neutron, before you factor in any inefficiencies.
You can't get ahead spending 10 MeV …
5
votes
Accepted
Luminosity of an elastic proton-proton scatter
You do not need the volume. You need the number density,
$$
n=\frac NV=\frac p{kT}
$$
Then the product $n\ell$, with $\ell$ the known thickness of your target, is the number of scatterers per unit are …
4
votes
What is the SI unit for the mass of subatomic particles?
The SI unit for mass is the kilogram.
Most organizations which insist on SI units will make an allowance for the fact that the kilogram is inconveniently large for discussing masses in atomic and suba …
4
votes
Why does quantum theory predict that there are an infinite number of quark-antiquark pairs i...
However, that only works because protons, neutrons, and electrons are subject to “number conservation laws.” … Protons and neutrons are “baryons,” and there is no known process which can change the number of baryons in a closed system. …
4
votes
What happens to the electron in a beta minus decay?
The answer by annav is correct that the neutron decay products will travel in straight paths in a vacuum chamber; the electron and proton will interact with the walls of the chamber, slow down, and be …
3
votes
Accepted
What happens to mass during beta decay?
This means, among other things, that neutrinos emitted from neutron decay at rest will never have enough energy to cause positron emission on protons at rest elsewhere. … For instance, the mass difference between postassium-40 and argon-40 is about $1.50\,\mathrm{ MeV}/c^2$, with potassium (19 protons) heavier than argon (18 protons), so the decay
$$
\rm ^{40}_{19}K \to …
3
votes
Accepted
Is there a $\mathrm{p}^0$ particle?
It looks like a typo for
$$ \rm \rho^0 + n \to K^+ + \Sigma^- $$
where $\rho^0$ is the uncharged member of the isospin triplet with mass 770 MeV.
According to the particle data group, the quark conten …