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.)

Filter by
Sorted by
Tagged with
0
votes
3answers
75 views

What is the SI unit for the mass of subatomic particles?

Question: What is the SI unit for the mass of subatomic particles? Notes: The weight of a proton is about $1.7 \cdot 10^{-24}\mathrm g$. This is the same as 0.0000000000000000000000017 grams. This is ...
3
votes
0answers
38 views

How can I visualize the oxygen nuclear charge density?

Oxygen has 8 protons and 8 neutrons. Based on the nuclear shell model, protons should pair with anti-parallel protons to create singlet spin states, and neutrons should similarly pair with anti-...
0
votes
0answers
38 views

Special relativity particle creation

A photon hits a proton that is at rest (In the lab system) which creates a pion, so now there are only the proton and pion. The question is what minimal energy can you give a photon such that this ...
0
votes
2answers
54 views

Is there any difference in the the electric field of a proton and an electron?

The question which I was wondering about was that how does a positive charged particle know that the other particle is positively or negatively charged? Then I thought that maybe there is some ...
0
votes
0answers
24 views

Why does Bragg peak exist for protons?

I am doing some research on proton therapy and I don’t understand why a Bragg peak exists. From Wikipedia, it says that A peak occurs because the interaction cross section increases as the charged ...
2
votes
1answer
38 views

Neutron to proton transition matrix element

I am reading the book Advances on Nuclear Physics vol 13 by J. w. Negele and Erich Vogt. On page 33, one is going to calculate a matrix element corresponding to a transition of a neutron to a proton. ...
1
vote
1answer
65 views

Why can the neutron not be measured in this fixed-target experiment?

Consider a fixed-target-experiment, where negatively charged pions are shot at protons (the latter being at rest). The kinetic energy of the pions shall be known. One possible reaction is $$ \pi^- + p ...
1
vote
1answer
34 views

The speed of a particle when instead of pure circular motion it is forced to do a helicoidal-circular motion [closed]

Is it right that if a proton is trapped in a magnetic field it is forced to do a circular motion of a distinct radius.Now, if a quark inside that proton does a rotation inside the proton volume can ...
0
votes
0answers
30 views

Why don't electrons and protons collide inside Atom? [duplicate]

I was thinking of atoms. Usually atoms have same amount of electrons and protons. While electrons are negatively charged and Protons are positively charged. As we know from coulomb's law that positive ...
7
votes
2answers
433 views

Is it possible to create protons from photons?

I've read a few pages on related topics (e.g., here) but not found this question. Is this type of reaction theoretically possible that we know of? I know pair production creates electron and positrons,...
1
vote
0answers
41 views

What is the shape of the quark structure in a proton or neutron? [duplicate]

I know the pictures we see are just a representation to help people understand what is going on while in reality the quark is likely a wave vs a particle. That being said it is always depicted as a ...
1
vote
1answer
95 views

Is it theoretically possible for a proton to travel fast enough to destroy the sun by virtue of its relativistic mass?

I realise this is a (slightly) nihilistic question but lock down and all... Is it possible to destroy the solar system by launching a proton at the sun at a speed approaching c (as seen in cern 0....
0
votes
4answers
89 views

Why aren't protons constrained in the same way electrons are?

I am fairly new to quantum physics, and I have been told that electrons, when inside an atom, only fit in discrete orbitals/wavelengths. I understand why this happens. My question is, protons also ...
2
votes
2answers
344 views

How does protium-protium fusion work?

How does protium-protium fusion work? As far as I know, a proton turns into a neutron by emitting a positron. How does that work? Shouldn't a proton be slightly lighter than a neutron? This seems to ...
0
votes
0answers
41 views

Crossing symmetry violation by passing from proton-proton scattering to proton-antiproton scattering?

The elastic proton-antiproton $(p \bar p)$ scattering is a crossing symmetric process of elastic proton-proton $(pp)$ scattering. It is known from Regge theory that the elastic $pp$ and $p\bar p$ ...
1
vote
1answer
50 views

Is the motion of proton in EM described by the Schroedinger equation?

Does the usual Schroedinger equation describing the non-relativistic motion of electron in electromagnetic field also describes non-relativistic motion of proton? (Of course the values of charge and ...
19
votes
11answers
5k views

Why the charge of the proton does not transfer to the neutron in the nuclei?

For example, when we put two objects of +10C and +20C together and then take them apart, each of them acquires a charge of +15C. In a nucleus, the protons and neutrons are stuck together. Why is it ...
1
vote
0answers
30 views

Why does changing the number of protons cause such a fundamental change in an element? [duplicate]

When we change the number of electrons in an atom of an element, it constitutes an ion. When we change the number of neutrons of an element it constitutes an isotope. But when we change the number of ...
2
votes
1answer
40 views

Stable number of neutrons for a given nucleus with $Z$ protons [closed]

I have been trying to derive an expression for the stable number of neutrons using the semi-empirical mass formula. I tried to derive it by dividing the Ma by total number of nucleons and then ...
1
vote
0answers
58 views

Where does the mass of a proton come from? [duplicate]

I just read that the mass of a proton is one hundred times more than the sum of the masses of the quarks composing it. Now, I know that these numbers (the mass of the proton and the sum of the masses ...
2
votes
3answers
54 views

Can protons have orbital if they gain more energy? [closed]

I read that because a proton is much more massive than electron but an electron has slightly more energy so it doesn't fall into the nucleus and orbital is due to the constructive interference of ...
4
votes
2answers
143 views

Can we be sure that leptons and baryons gravitationally attract each other?

Covid has renewed my interest in fundamental physics. But I notice that my knowledge has rusted a little bit over the years. So please bear with me. Since unification of gravitation and quantum field ...
3
votes
2answers
75 views

What is diffractive dissociation in collisions?

Correct me if I am wrong: If we collide protons with protons then we can have elastic scattering, inelastic scattering (large momentum transfer between partons), and diffractive dissociation. I am ...
1
vote
1answer
39 views

What is the contribution of sea quarks to proton mass?

I've read in this article that the 3 valence quarks make up only 0.2% of the mass of a proton (or neutron) and the remaining 99.8% comes from gluons. From other sources we know that there are an ...
1
vote
2answers
64 views

Probability of forming a proton or neutron with loose quarks?

If I had two unbound up quarks and a down quark or two unbound down quarks and an up quark, what is the probability, if I bring them close together, they stick and form a proton and a neutron, ...
1
vote
2answers
76 views

What happens to the rest of the 95 percent in quarks? [duplicate]

Quarks are bound by gluons. Gluons have a mass of 0, while mass of quarks is only 5%. Where is the missing 95%?
20
votes
4answers
4k views

Can an electron and a proton be artificially or naturally merged to form a neutron?

My sense is that even though neutrons decay into a proton and an electron they are made up of quarks, it is not just some "merged" particle where, for example, the electron is orbiting the ...
0
votes
1answer
96 views

Significance of minimum energy of a proton [closed]

I have been presented with the following problem. A neutron is confined in a nucleus of size $4 × 10^{−15}$ m. Using the Heisenberg Uncertainty Principle, estimate its minimum kinetic energy. Comment ...
2
votes
1answer
200 views

Filling order in the Shell Model of the nucleus

I have read that, in the nuclear shell model, nucleons are distributed filling energy levels following the Pauli exclusion principle. These energy levels can be designed with the $nl_j$ notation: $1s_{...
4
votes
3answers
1k views

Proton Antiproton collision

Can it be possible to form an electron-positron pair from a proton-antiproton collision through the following interaction? $$p+\bar{p}\rightarrow[X]\rightarrow e^-+e^+$$ Where [X] is a particular ...
2
votes
1answer
71 views

Pauli exclusion principle: why does it imply that $Z\approx N$ in stable nuclides with $A<40$?

I have read that when representing the possible nuclides in the $(Z,N)$ plot, the stable nuclei located on the line $N=Z$ for $A<40$, and that this is due to the Pauli exclusion principle. I have ...
0
votes
2answers
75 views

Why is the charge of electron not taken as negative when calculating the electrostatic force between the nucleus and electron in Bohr's model of atom?

In one of the postulates of Bohr's model of hydrogen atom it is said that "While the electron revolves, the electrostatic force between the electron and nucleus provides centripetal force. The ...
2
votes
1answer
68 views

Is proton easier to remove from a nucleus than a neutron?

Which factors will we consider for deciding whether a proton is easier to remove or a neutron? Considering Coulombic forces, proton experiences repulsive force and hence easier to remove. But why will ...
13
votes
3answers
3k views

Is the nucleus smaller than the electron?

In the classical incorrect 'billiard ball' model of the atom, electrons are often drawn as smaller balls than the protons and neutrons in the nucleus. However from quantum mechanics we know the ...
0
votes
0answers
18 views

Why low energy electron-proton colision cannot simply produce neutrons?

Can low energy electron-proton collision produce neutrons (and neutrinos)? I asked many of my physics teachers but they said that it would produce hydrogen atoms instead. Some explained this because ...
-1
votes
3answers
268 views

How can we split a proton? [closed]

I have heard the following statements: Quarks always exist in a group of 2 or 3, and can not stand alone. Protons are made up of 2 up quarks, and 1 down quark. Quantum mechanics allows us to entangle ...
11
votes
3answers
1k views

Does the Electric Field Instantaneously vanish during an Electron Capture?

When an Electron Capture occurs a Neutron and a Neutrino are formed. Prior to this process due to the presence of the proton and electron an electric field must've existed however as soon as this ...
1
vote
0answers
29 views

Polarized proton beam

Can someone explain to me or point me towards some references about how can one obtain experimentally a polarized proton beam. I find many talks about using siberian snakes to preserve the ...
0
votes
1answer
66 views

Deep inelastic and Bjorken limit

In DIS the Bjorken limit is given by the conditions: $Q^2 \rightarrow \infty$, $\nu \rightarrow \infty$ and $x=Q^2/(2M\nu)$ is finite, where $Q^2$ is the opposite of the transferred momentum, $M$ is ...
25
votes
5answers
6k views

Are protons bigger than electrons?

In every text/ physics book that I've read, Protons are mentioned as particles that are bigger, way bigger 2000 times to be precise, than electrons...I believed that until a few minutes ago when I ...
1
vote
1answer
47 views

Proton as viewed from an orbiting electron's perspective

When I see depictions of the electron orbital of a hydrogen atom, I see a static proton in the center surrounded by an electron cloud. What would it look like if we shifted the reference frame to the ...
0
votes
1answer
34 views

How do I reduce proton number of an atomic nucleus?

I know that one can increase proton number of an atomic nucleus by proton bombardment as Cockroft and Walton bombarded elements with protons and managed to increase the atomic number. However, how can ...
0
votes
1answer
47 views

Help in recovering the Rutherford formula for $ep\to ep$ scattering in the nonrelativistic limit

If the proton were a point charge like the muon, then $ep\to ep$ scattering, the differential scattering crossection is $$\frac{d\sigma}{d\Omega}\Bigg|_{\rm lab}=\Bigg(\frac{\alpha^2}{4E^2\sin^4(\...
13
votes
5answers
3k views

Why is the mass of the proton such a precise value?

Why is the mass of the proton such a precise value? A proton is composed of 3 net valence quarks and what is often described as "binding energy" or "a zillion gluons and quarks and anti-...
0
votes
1answer
80 views

Why are atomic nuclei protons and neutrons, and not electrons and neutrons or protons and neutrons

Wouldn't proton-electron nuclei be more stable since they attract each other and aren't just neutral to each other? What is the reason for this? I tried searching for an answer but couldn't find ...
-2
votes
2answers
69 views

Beta ray maximum energy

I recently participated in a classical experiment that can calculate the maximum energy of a beta radiation emission (for Tl-204). When I searched the internet for other results for comparison, I ...
-3
votes
2answers
77 views

Is there any reaction where electrons or protons get directly converted to energy, and are destroyed as a consequence?

This question is not about fission or fusion reactions, or changes in mass/energy as the speed of a particle changes. The number of protons (including protons within neutrons) and electrons pre- and ...
26
votes
3answers
2k views

Why no proton microscopes? Proton diffraction; or proton scattering experiments? Proton crystallography?

I am asking a (relatively) 'low-energy' question here, not about things like the Large Hadron Collider... There are tons of articles everywhere, including such places as Wikipedia and ScienceDirect, ...
2
votes
1answer
35 views

Which properties of individual nucleons change depending on the nuclear environment?

Free neutrons are unstable (half-life $\sim 10$ min), but bound neutrons are (for many nuclei, including those which are stable) stable. Question 1: Are there other properties of the neutron / proton ...
1
vote
2answers
37 views

Doesn't the neutron's lack of an electric dipole moment conflict with the concept of baryons having a radius?

The proton radius puzzle appears to one of the more widely known unsolved problems in physics, but doesn't it point to a much deeper issue? Nearly all of a baryon's observed mass can be attributed to ...

1
2 3 4 5
8