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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Isospin vs. proton neutron formalism?

The isospin formalism is that we consider proton and neutron as the same particle with different isospins. If we have a two body problem with proton and neutron (deuteron), we can treat this with the ...
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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-...
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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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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What is a structure function (or proton structure function)?

Can someone explain structure functions (proton structure functions)? I know they are used to study or understand the structure of protons , but does there exist a particular formula to calculate ...
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Symmetries of proton-neutron interaction

I am following Sidney Coleman's lectures of Quantum field theory, where in ch 24 (page 509) he wrote down the non-derivative pseudoscalar type interaction Lagrangian between the proton $p$ and neutron ...
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How can we knock out a proton specially to change one element to another?

I know one can simply excite a nucleon from a nucleus by radiating gamma rays on that nucleus, or knock the nucleus with neutrons or protons. But how can we knock out a proton specially to change one ...
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Why do we ignore the proton when computing relativistic correction in the Hydrogen atom?

I have read a number of textbooks (e.g. Sakurai), and they all seem to say that the unperturbed Hamiltonian of hydrogen is: $$ H_0 = \frac{p^2 }{2m_e} - \frac{e^2}{r} \tag{1} $$ and the relativistic ...
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At what radius from nucleus does an electron reach the speed of light?

Let's forget about the quantum knowledge here. Lets say that we just want to know what speed an electron can get, when falling straight on to a nucleus. It does not miss the nucleus and start ...
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Energy dependence on bragg peak width

If you look at this plot of proton Bragg peak at different energies. You can see that the Bragg peak shifts right (which makes sense) but also the height and I think the width of the brag peak is ...
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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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What enters in the structure of neutrons and protons in the nucleus of an atom? [closed]

What is the smallest substance in the universe discovered, and it enters in the structure of neutrons and protons in the nucleus of an atom?
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Infer position of proton from that of another?

I'm a computer science student, so please be patient with my simple understanding of physics. I heard that if we have a proton, then it does not have a definite position until we measure it. Suppose ...
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How much energy is required to fuse two protons? [closed]

What is the kinetic temperature required to fuse two protons in a plasma? How much energy does it release? What are the products of the fusion reaction?
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Lithium Proton Fission [closed]

What will happen if I fire a proton beam at a Lithium-6 nucleus? What products will it produce? Is it exothermic and if so, how much energy is released? How would you calculate it?
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Protons and electrons near each other

For context: I am an electrical engineer planning to do a masters in photonics. So I've been studying electromagnetics and trying to understand it with a little more depth than what undergrad ...
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Why the Binding Energies of Neutron and Proton are different?

In my textbook, Problems in General Physics by I E Irodov there is following problem: I am able to solve the problem. I am able to do all the maths, to the right answer, but I have a conceptual doubt....
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Is proton + antiproton $\rightarrow$ $\pi^0$ meson allowed?

I’ve checked baryon no., lepton no., charge, strangeness and isospin, everything seems to be conserved which would suggest it’s an allowed strong interaction, but I feel like it’s wrong. I tried to ...
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Proton Structure and Parton Distribution Function

I recently read a question about whether photons, electrons, neutrinos... are a part of the proton since there are these sea-quarks he learned about. And the answers were confusing to me because the ...
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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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Why protons are stable but Neutrons not?

just read something about standard model and find it very interesting, proton is made of there subatomic particle U,U,D and neutron have U,D,D . electromagnetic force between U,U,D wants to rip apart ...
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When exactly are protons attracted to other protons and neutrons?

When proton and proton neutron and neutron proton and neutron are attracted to each other or repelled from each other in terms of strong interaction (ignoring electromagnetic interaction)? I read ...
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What is the total number of protons in the observable universe?

What's the total number of protons, is it equal to the number of electrons? What is the Eddington number and how is it found?
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1answer
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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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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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Pressing questions about the annihilation of a particle & an antiparticle

A charged particle (e.g. proton) meeting with its own charged antiparticle (e.g., antiproton) annihilates and energy is given off in the form of radiation. Do we have any clue why this happens? Does ...
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Can neutrons and protons have excited states?

Anything with a substructure has excited states. Molecules, atoms, nuclei all can absorb photons which causes them to make a transition to an excited state. Conversely, when they jump from an excited ...
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Why will the number of neutron higher than the number of proton in the most of atom? [duplicate]

The chinese website said : In the most of atom,the number of neutron higher than the number of proton Does anyone know the reason?just explain it in easier way, Or does anyone know if the number ...
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How would we know that Dirac equation does not describe composite spin-1/2 fermions?

How do we know that the quanta of a quantized Dirac field describe elementary spin-1/2 fermions (or point particles of spin-1/2) and not composite spin-1/2 fermions (or extended structure of spin-1/2) ...
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If quarks change colours constantly how are proton and neutron stable relatively?

Say for example a proton is composed of Up, Up and Down (valance) quarks and suppose the Down quark absorbs a gluon, Down quark must change colour in order to conserve colour charges but so must the ...
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What is the relationship between charge and mass of electrons and protons? [closed]

Proton and electron have equal and opposite charge but they have a different mass how is this possible
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Why don't we have 'inverted' atoms with electrons in the nucleus and protons orbiting around? [closed]

I just wanted to ask: What if the structure of an atom was inverted at the level of the charges? I mean that instead of the protons being in the nucleus it is an the electrons that constitute the ...
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Measuring the size of the proton from the hydrogen atom spectrum?

I was reading that besides measuring the angle of ricocheted electrons bouncing off the proton to pin down its size, it is also possible to excite the electron and then measure the frequency of the ...
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Can string theory explain why the charge of the positron and of the proton are equal? [duplicate]

There is not much more to elaborate. Can string theory say why electrons and protons have exactly opposite charge? And thus why hydrogen atoms are neutral? I guess that the answer is no, because ...
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Is it possible to create an atom, proton, neutron and electron?

I know that it is not possible, however, this thought keeps me awake and make me thinks a lot. Is it possible to create an atom artificially from free protons, electrons and the neutrons??
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Transverse momentum in the parton model

Why is it so important that the partons in the parton model have low transverse momenta? And transverse to what anyway? I mean, basically one looks to justify breaking the hadronic subgraph in hadron-...
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1answer
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How do we know that the charges in an electron and a proton are equal? [duplicate]

An electron and a proton have opposite charges. But how can we be so sure that they have equal amount of charge but opposite? Can't there be a slight difference?
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Why does the formation of deuterium involve the release of an antielectron rather than electron capture

In chapter 2 of Particle Physics Brick by Brick, Still describes the proton-proton chain which involves a proton changing to a neutron at 2 different stages, once through decay and once by electron ...
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Why aren't Delta and Omega particles stable?

Not only are they not stable their half-life is in the nanoseconds. Why are they so different from protons?
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Two protons inside a negative sphere [closed]

Problem: Imagine a sphere of radius a filled with a negative charge density equal of two electron charge. Embedded in this is two protons, assume that the negative charge distribution remains uniform ...
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Matrix element involving virtual external state?

When using the QCD-improved parton model, we often calculate matrix elements for the scattering of a virtual photon off a quark. $$\gamma^\ast q\rightarrow q$$ In general, we consider the deep ...
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How do electron on electron collisions affect the protons attached to each electron?

If an electron collides with another electron would the force exerted on the electrons pass a force onto their opposing protons and make the neutrons jiggle about a bit while equilibrium is re-...
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Is charge quantization correctly interpreted in classical electrodynamics?

As I tried to answer the SE question Electric fields in continuous charge distribution, I faced many ambiguities regarding this matter. In classical electrodynamics, it is claimed that the electric ...
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The importance between of the difference of the proton and neutron electromagnetic structure functions $𝑆_𝐺$

There is a famous momentum sum rule given by Gottfried, where the sum rule can be violated considering the flavor of $\bar u$ and $\bar d$ are not symmetric. The violation was proved by one experiment ...
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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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