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Questions tagged [protons]

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.)

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How do you read the spin contributions of proton

This paper reads the number of their results. I'm attaching the how they have included all the spin contributions of quarks to proton. The contributions are from u, d, s quarks. How I can tell ...
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Is there a difference in wavelength emission spectra of ZnS:Ag when its irradiated with protons vs. gammas?

How would I measure this, because I couldn't find this information in literature as of yet? I have neutron (to produce protons by recoil) and gamma sources, but I don't have a pure neutron source, and ...
14 views

Velocity of particles in electrolysis

In an electrolysis (H20) water is split up and the protons start to move towards the anode. So one would be able to calculate the acceleration of the proton from the electric field in that area. ...
7k views

Can there be an atomic nucleus where there are more protons than neutrons?

As far as I know, number of protons is less that or equal to the number of neutrons in any atomic nucleus. But is there any possibility that there exists a nucleus where the number of protons exceeds ...
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Alternative symmetric spin + flavor part of a proton?

I have a doubt about the proton's quark structure. All sources I've read agree that the following is the quark structure of the spin-up proton (this one is from Griffiths' Introduction to Elementary ...
335 views

How did we know that the Dirac equation describes the electron but not the proton?

I'm suddenly getting confused on what should be a very simple point. Recall that the $g$-factor of a particle is defined as $$\mu = \frac{ge}{2m} L$$ where $L$ is the spin angular momentum. For any ...
1k views

How is the speed of nucleons in the nucleus measured?

This article claims that "nucleons in a dense nucleus exceed 25 percent of the speed of light". How do you measure or infer the speed of nucleons in the nucleus? Note added later: I'm looking here ...
9k views

How do we know neutrons have no charge?

We observe that protons are positively charged, and that neutrons are strongly attracted to them, much as we would expect of oppositely charged particles. We then describe that attraction as non-...
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How much does the distance between electron orbits shrink as proton number increases?

I was watching a YouTube video that briefly mentioned the electromagnetic attraction between the nucleus and it's electrons increases as the proton count of an atom increases. I'd never considered ...
16 views

How does positron emission happen naturally? [duplicate]

How does positron-emission happen naturally, for example in Potassium-40? Isn't the added mass of the neutron and the position more than the mass of a proton? Where does the proton get this extra ...
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If protons are the only stable baryons, why do they decay into neutrons in positron emission?

Surely I must have a misconception?
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Recombination of hydrogen

Suppose a slow-moving electron and a slow-moving proton are injected into a chamber, such that the two approach each other and are likely to combine to form an atom of hydrogen. How would one ...
2k views

Does a proton have a binding energy?

When calculating the $Q$-value, $Q = \Delta M \cdot c^2$, of this reaction: $$^6Li \ (\alpha, p)\ ^9Be \quad \iff \quad \alpha + \ ^6Li \ \longrightarrow \ ^9Be + p$$ The $Q$-value can also be ...
88 views

Most of the momentum of a proton is carried by the quarks

I saw this in wiki https://en.wikipedia.org/wiki/Antiproton#Modern_experiments_and_applications "the valence quarks in the proton, and the valence antiquarks in the antiproton, tend to carry the ...
92 views

Does an atom or proton (cosmic ray) get stretched when traveling through expanding space?

I have read this question: Why does space expansion not expand matter? I do understand that matter inside galaxies will not get stretched because inside galaxies, gravity dominates over dark energy. ...
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Are / Why are the H II regions positively charged?

One of the questions in our recent astrophysics course homework was to find the general opacity $\kappa$ of H II regions. We know that the H II regions are almost entirely ionized hydrogen and I ...
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Modelling Proton Beams using Numerical Methods

I'm attempting to model proton beams/proton therapy using numerical models in MATLAB. I'm having trouble tracking down the correct master equations to use to model beam energy (60-250MeV range) ...
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Limit to number of neutrons in nucleus [duplicate]

As far as I understand the number of protons in a nucleus is limited because Coulomb forces grow faster with the number of protons than the nuclear force. So alpha/cluster decay limits the size in ...
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Would protons in a straight line ever break their alignment? [closed]

Let any amount of arbitrarily spaced protons appear along a line segment of length $x$ in an otherwise empty universe at $t+0$ What mechanism, if any, could cause the breaking of said alignment ...
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formation of atomic nuclei from nucleons

What holds the nucleus together? In a nucleus there are several protons, all of which are positive. Why don't they push themselves apart? It turns out that in nuclei there are, in addition to ...