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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What is the cause of the minor mass difference between the proton and the neutron?

As known, the proton is from two up and a single down quark, while the neutron is from a single up and two down quarks. The down quark is a little bit more massive and the up, and so the neutron is ...
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Quark intrinsic angular momentum and the Proton Spin Crisis

According to recent results regarding the "Proton Spin Crisis", apparently only about 30% of the total angular momentum of the proton comes from the intrinsic angular momentum of its constituent ...
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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-...
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Angle between velocities: Elastic collision question in 3D

I have been given a scenario of a proton (particle 1) travelling with u1 = 3î+ 4j–6k and a Helium-3 nucleus (particle 2) travelling with u2= 3î+ 4j–2k. The two particles collide and the proton (...
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Magnetic moments of nucleons

I was comparing my notes of the nuclear physics class (undergraduate level) on magnetic moments of nucleons with the Krane's explanation. In my notes I wrote that there are two types of magnetic ...
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Proton structure: are there photons, electrons and neutrinos in there too?

I've read that the proton is not simply made up of three (valence) quarks; rather, there is a continuous exchange of gluons between the three quarks, and these gluons can produce quark-antiquark pairs ...
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159 views

Why is the GZK cutoff at such high energies?

Why is theGZK cutoff at such high energies? The threshold energy for Compton scattering is 0.511 MeV. But the inverse Compton scattering has a very high energy threshold. For example in ...
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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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In the case you entangle two free protons, how are the quarks in one proton entangled to the quarks in the other proton?

The three quarks (uud) in a proton are held together by the strong force, and the overall e.m. force between the quarks is repulsive but much weaker, so the quarks stay together. Now two free ...
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85 views

How many different experimental configurations does the Large Hadron Collider have?

I understand that the LHC can collide protons with protons, heavy ions with heavy ions, or protons with heavy ions, giving three main configurations. But, I'm wondering: is that the only property that ...
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If the measurement of the proton size is correct and it is lower that it was expected than what are the theoretical implications?

In the press release of the recent measurement of the proton structure, they barely mention various theoretical explanations for the effect. What is the most likely (not assuming now that the ...
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326 views

How are the spins of three quarks in a nucleon aligned?

A proton is composed of uud. Are the two up quarks paired up to cancel each other's spin or are one up quark and one down quark paired up? I know the three quarks may only carry a small proportion of ...
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41 views

Modelling ions hitting a grid

I want to model the capture of ions by a negatively charged grid made of some proton conductor material like graphene oxide. Are ions captured as soon as they cross the surface, or do they have some ...
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Why choose frozen hydrogen for proton spin polarization testing?

Is frozen hydrogen particularly good for polarizing proton spin? Or are other elements particularly bad? It takes quite an effort to reach the near absolute zero necessary to freeze hydrogen. See ...
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Is there any meaningful notion of a probability distribution for the number of quark-antiquark pairs in a hadron?

A hadron (such a proton) can be thought of as being composed of a large (but fluctuating) number of quark-antiquark pairs. As far as I understand it, the situation (say for a proton, for definiteness) ...
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97 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....
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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 ...
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Is proton diffraction more difficult to obtain experimentally?

I was studying the phenomena of particle diffraction and saw that any particle can be associated to a de Broglie wavelength, given by $$λ=\dfrac{h}{p}$$ Experimentally, we commonly talk about the ...
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Upper bound proton/electron excess in the universe?

There are presumably very nearly equal numbers of protons and electrons. But is there any bound on their ratio ?
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How do I estimate the endpoint energy for the proton?

How can I estimate the endpoint energy for the proton in the neutron beta decay? Following this answer, I can write the system of equation as: $$p_e+p_p+p_\nu=0$$ $$m_n=E_p+E_e+E_\nu$$ Assuming ...
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What percent of the mass the proton comes from its electric field energy density?

How much heavier would the proton be with respect to the neutron if the up quark and the down quark had the same mass? How much does the electric field energy density of the proton contribute to its ...
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660 views

Total positive charge in the Universe

In their last homework, some of my students miscalculated a charge to be $10^{20}$ C over a squared meter and I was wondering if there was as much positive charges in the entire Universe. It would do ...
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Are the arrangements of quarks in hadron ground-state wavefunctions rotationally symmetric?

The Hamiltonian of quantum chromodynamics (like the rest of the Standard Model) is rotationally symmetric. My question is whether these space symmetries are spontaneously broken in the ground state of ...
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Structure function of the proton

I am trying to visually (sketch) understand how the structure function of i.e proton changes when we consider it like a sphere or as a constitute of interacting or non interacting quarks. ...
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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 ...
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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 ...
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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 $p\bar p$ ...
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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 ...
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Nuclear force and binding energy

What i read about binding energy is that it is the energy released when nucleus is formed due to the attraction of the strong nuclear force between nucleons. But even after the nucleus is formed, the ...
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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 ...
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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. ...
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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 ...
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What is the theoretical charge radius of a proton?

Today I read this news article and this Wikipedia page that talk about the 'Proton radius puzzle', where discrepancies have been observed between values of the proton charge radius, when measured ...
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Synchrotron radiation for protons

I know that due to the huge mass difference and dependence of radiated energy on mass, protons lose much less energy in synchrotrons than electrons. Can someone tell me how to calculate the energy ...
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How do I calculate how strong of a field I need to repel a proton in a span of time

How do I calculate how strong of a field I need to repel a single proton in a given span of time, given that I know it's velocity.
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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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56 views

Minimum energy of proton converting into a neutron

I'm given the isotope sodium 22 (which is positron emitter) and I'm stuck with calculating the minimum energy that a proton needs to convert into a neutron and a positron. It got to do with $E=MC^2$ ...
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Is there a mass spectrometer software that can measure the mass of a proton

I spent a lot of hours looking for mass spectrometer software (or Cathode-ray simulator) that can measure the mass of a proton or any sub atomic particle. Until now I only found software that work on ...
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Seperating Charges in a Cell

Sorry for not being detailed for my question here but how do charges seperate in a cell and when the electrons are pumped out of the battery does it return and become positive ? Yet again sorry if I ...
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Why charged particle interaction cross section increases as the particle's energy decreases?

I'm tying to gain a little more understanding of the dose deposition profile of high energy (~100MV) protons in matter (depth dose curve - medical physics). I understand that the Bragg peak occurs ...
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Protonic emissions

In a beta emission a neutron decays,into a proton and an electron, and an electron randomly gets ejected from the nucleus due to the phenomenon of barrier tunnelling(correct me if am wrong).But why is ...
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What is the kinetic energy of a proton as it is falling towards the core of the star?

Given: Star's mass = $1.99e10^{30}kg$ Type II supernova occurs (in a simple form: the outer layers of the star fall into the now inactive core at speeds of 126000km/s) $10^{44}$ joules of energy is ...
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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 ...
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306 views

Electrostatic force between two grains of sand with unbalanced charge placed 30 meters apart

Quote from The Feynman Lectures on Physics Volume I: To give an idea of how much stronger electricity is than gravitation, consider two grains of sand, a millimeter across, thirty meters apart. ...
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Where is the mass of a proton coming from? From empty space or gluonfields?

Protons are made quarks and bosons. I think most physicists would agree that the mass of a proton is not coming from the quarks itself. About 90% is coming from something else, but what is that. I ...