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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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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 ...
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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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How much of the proton's mass is due to the Higgs field?

The proton mass is 938 MeV. People often claim that (A) The proton is a bound state of two up quarks and one down quark, with the three quarks contributing a total rest mass of $2 \times (2.2 \text{...
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Measurement of spin asymmetries in semi-inclusive deeply inelastic scattering (SIDIS)

I have been reading several papers regarding the spin asymmetries for SIDIS. One thing I was trying to understand is the method of extraction of symmetries. When I read the single spin asymmetries, ...
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What happens to the electron when a neutron knocks off a proton from hydrogen atom?

In recoil proton scintillators, the hydrogen acts as a neutron converter to produce protons when a neutron strikes a H atom. But what happens to the electron in H atom? Where does it go? Does it ...
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Why does the nucleus not repel itself? [duplicate]

If the nucleus is densely positively charged, why don’t the protons in the nucleus repel from each other and move towards the orbiting electrons? Because each proton is not only being repelled by the ...
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How would the structure function of protons be different if quarks had spin 0?

I saw this question in a practice exam. I know that the structure functions are not linearly independent but that $F_2(x)=2xF_1(x)$ when the energy is in the order of GeV. The question asks what ...
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Why does the conclusion that protons are monopoles has led us to believe that they specifically may have a half-life? [closed]

from Zeldovich, Ya. B.; Khlopov, M. Yu. (1978). "On the concentration of relic monopoles in the universe": "The majority of particles appearing in any quantum field theory are unstable, and they ...
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What devices are used in a proton accelerator to separate the protons from their electrons and send the protons into the vacuum chamber? [duplicate]

I understand the general idea of how they accelerate the protons once they get them isolated in the chamber, but what's the device they use to isolate them to begin with even called?
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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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Why protons and electrons attract each other? [duplicate]

This YouTube video states that electrons and protons are bonded together by emitting electromagnetic waves and absorbing each other's electromagnetic waves. But isn't because it due to potential ...
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Energy budget of of proton-proton fusion (p-p chain)

How much energy is released in the first nuclear reaction of the p-p chain which produces energy in lower-mass stars like the Sun? The value of 1.44 MeV is given in many sources, but I don't ...
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Why does this quiz question say that protons and electrons do not combine to form neutrons?

I read this somewhere: Where are the protons and electrons in a neutron star? When the neutron star forms, most of the protons and electrons combine together to form neutrons. But on a true/false ...
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What is the effect of isospin on the proton or neutron alone, i.e. not in a doublet?

So I start with a proton $p$. I extend my "physical" space by means of the internal degree of freedom of isospin, so that I know write $p$ in a higher dimensional space: $$ p = \left( \begin{array}{...
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How would a difference in electron and proton charge be detectable in astronomy?

How would a deviation in neutrality of matter affect astronomy? Obviously this would introduce a lot of repulsive force but how, exactly, would that affect the universe? If the repulsive force was ...
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Do electron really experience any repulsive force while attracted by proton compared to positron?

I read up that the reason 2 electrons with same energy states can be binded to the first orbital of a necleus is due to one electron having positive spin half and another having negative spin half ...
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Can you fake protons with light?

I have been reading similar discussions on how protons and electrons interact, using virtual photons and such. Yet, I can find little information regarding the subject in question. Can a beam of ...
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What is the upper limit for the size of an atom? [duplicate]

I read an article saying an Israeli scientist had discovered the heaviest nucleus with 122 protons and 170 neutrons, and found it in a sample of purified thorium, and I would like to know if there are ...
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Stability in Nuclear Shell Model

As far as I understand , a particular sub-shell is filled with either protons or neutrons, $2*(2l+1)$ number of them, and never both together since protons and neutrons fill up levels separately in ...
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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 ...
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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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Why is neutron slightly heavier than the proton? [duplicate]

With latest knowledge of QCD, is there any explanation for why the neutron is slightly heavier than the proton? Can it be boiled down to a simple formula?
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Does a proton bend spacetime?

Protons have mass and as a result of einstein's field equation dictate that the spacetime is no longer flat. But yet I find in most Quantum Field Theory books the Minkowski flat spacetime metric is ...
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Is a nucleus a collection of quarks or a collection of neutrons and protons? [duplicate]

I do not much about particle physics. But people say that neutron and proton are composed of quarks, and in turn a nucleus is composed of neutrons and protons. Therefore, the question is, is this ...
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Collision of a photon with a quasi-free particle

What is a quasi-free proton? How does the wavelength of a photon change when it collides with a quasi-free particle, e.g. a quasi-free proton?
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Nuclear Fusion Proton-Proton Chain

When hydrogen nuclei are able to overcome the coulomb forces, two protons collide. As a result, one of them decays into a neutron and a positron and electron neutrino are emitted. However, isn't mass ...
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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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In a quantum state, Maximum how many protons & neutrons can exist?

This is in reference to the statement I have read in a book i.e., " each quantum state can contain at the most two protons (with opposite spin) & two neutrons (again with opposite spin)". So what ...
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What is the experimental evidence that the nucleons are made up of three quarks?

What is the experimental evidence that the nucleons are made up of three quarks? What is the point of saying that nucleons are made of quarks when there are also gluons inside it?
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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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High spin for $Δ^{++}$ resulting from angular momentum of pion in relation to proton

When a pion (Spin 0) collides with a proton (Spin 1/2) the result can be a Δ++ (Spin 3/2). When I tried to look up how the resulting Spin is possible, I came about an answer I do not understand. It ...
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Unstable vs. stable nuclei plotted on a graph

The enclosed graph shows the number of Protons on the x-axis (Z), and the number of Neutrons on the y-axis for all elements (N). Stable combinations are marked by black squares, whereas unstable ones ...
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Calculating the velocity of a proton through Relativity Theory

I was asked to calculate the velocity of a proton through Relativity Theory, with the following information given: -the Total Energy of the proton is 1,500 MeV -the resting mass ($m_0$) of the ...
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How to “build” a proton

Sabine Hossenfelder in her column The End of Theoretical Physics As We Know It made the following statement: For example, we have a perfectly fine theory that describes the elementary particles ...
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How are exchange terms in phenomenological nuclear potentials related to the exchange of nuclear force carrirer particles?

Consider a proton-neutron system. Phenomenlogical nucleon-nucleon potentials contain exchange forces terms (Majorana, Bartlett and Heisenberg terms), which are linked to the symmetry of the state w.r....
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How the Heisenberg principle holds for protons?

Does this principle holds for protons since their position is, in a manner of speaking, known and they are also assumed to be stationary at every popular physics book that I have read, including the ...
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In which experiment did protons seem to consist of infinite amount of quarks?

In this video Richard Feynman is telling that in some experiment it seems that the proton should consist of infinite amount of quarks. What is this case he's mentioning? Is it solved now?
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A proton's weak charge is .0719. Is this dimensionless? A ratio?

A recent piece of major news in the physics world is that the proton's weak-force charge was measured to be .0719. Is that a ratio? A dimensionless number, with no units? The articles I read ...
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Direction of Electron Field for Moving Proton

I had the following problem: A proton is moving to the right at constant speed v and enters a region with uniform magnetic and electric fields. It continues to move in a straight line. The ...
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Where is the proton mass coming from?

I always thought that the mass of a proton would simply be the mass of the three separated quarks plus their binding energies. Nevertheless, I was once discussing with one of the developers of RICH ...
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Creating isotopes by shooting neutrons into an unstable nucleus [closed]

I've been doing a lot of amateur research lately (youtube videos) on particle physics and find it all really interesting. I'm also a crazy alien conspiracy theorist who believes in the whole "Bob ...
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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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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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What is the reason for the shift in balance between neutrons and protons in the early universe?

In the book of The First Three Minutes by Weinberg, on pages 106-107, it is stated that SECOND FRAME. The temperature of the universe is 30,000 million degrees Kelvin [...] The nuclear particle ...
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How do we know that electrons are moving in an electric current?

We are learning about the Hall Effect in high school, but what confused us was that hypothetically if both protons and electrons were moving, but electrons moved much faster, then wouldn't there still ...
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Why is the proton anti-proton annihilation and pair production asymmetric?

This is a follow up question to this question. The process of annihilation is very well explained. However while the annihilation is a step-by-step process the pair production does not seem to follow ...