What is Nucleon: Definition and 72 Discussions

In chemistry and physics, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines an isotope's mass number (nucleon number).
Until the 1960s, nucleons were thought to be elementary particles, not made up of smaller parts. Now they are known to be composite particles, made of three quarks bound together by the strong interaction. The interaction between two or more nucleons is called internucleon interaction or nuclear force, which is also ultimately caused by the strong interaction. (Before the discovery of quarks, the term "strong interaction" referred to just internucleon interactions.)
Nucleons sit at the boundary where particle physics and nuclear physics overlap. Particle physics, particularly quantum chromodynamics, provides the fundamental equations that describe the properties of quarks and of the strong interaction. These equations describe quantitatively how quarks can bind together into protons and neutrons (and all the other hadrons). However, when multiple nucleons are assembled into an atomic nucleus (nuclide), these fundamental equations become too difficult to solve directly (see lattice QCD). Instead, nuclides are studied within nuclear physics, which studies nucleons and their interactions by approximations and models, such as the nuclear shell model. These models can successfully describe nuclide properties, as for example, whether or not a particular nuclide undergoes radioactive decay.
The proton and neutron are in a scheme of categories being at once fermions, hadrons and baryons. The proton carries a positive net charge, and the neutron carries a zero net charge; the proton's mass is only about 0.13% less than the neutron's. Thus, they can be viewed as two states of the same nucleon, and together form an isospin doublet (I = 1/2). In isospin space, neutrons can be transformed into protons and conversely by SU(2) symmetries. These nucleons are acted upon equally by the strong interaction, which is invariant under rotation in isospin space. According to the Noether theorem, isospin is conserved with respect to the strong interaction.

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  1. hongseok

    I Why the binding energy per nucleon has specific pattern?

    The binding energy per nucleon for each element has a specific pattern. It increases from hydrogen to iron and then decreases again. What is the fundamental reason why the binding energy per nucleon has this pattern? According to my investigation, the range of action of the strong force is...
  2. Y

    A Experimental nucleon form factors from electron-nucleus scattering

    I am looking for experimental nucleon form factors from electron-nucleus scattering. Is there any compliations or tables? In 'The proton charge radius ', H. Gao and M. Vanderhaeghen, Rev. Mod. Phys. 94, 015002 (2022), p. 24, there is 'world data on the proton and also the neutron'. In 'Form...
  3. R

    The binding energy per nucleon of tritium

    Hi, I know from conservation of energy that ##E_i = E_f## Thus, ## M_h c^2 + binding energy = M_{he}c^2+ M_e c^2 + K = M_{he}c^2 + 0.5 MeV + 0.0186 MeV## If I'm right I have to find ##M_{he}c^2##, but something is missing in my understanding, since I don't see how to find that mass energy...
  4. S

    I Upper end of nucleon overtones

    The spectrum of first generation resonances, counting Δ but including only 4 and 3 star particles (the latter in italics) goes: p(938)1/2+ n(940)1/2+ Δ(1230)3/2+ N(1440)1/2+ N(1520)1/2- N(1535)1/2- Δ(1600)3/2+ Δ(1620)1/2- N(1650)1/2- N(1675)5/2- N(1680)5/2+ Δ(1700)3/2- N(1700)3/2- N(1710)1/2+...
  5. leminn

    Binding energy per nucleon of the nucleus

    How exactly would it then be calculated? Here's what I have tried: proton mass: 1.007276 amu Neutron mass: 1.008665 amu Sulphur-34 mass: 33.9678668 amu Calculation: 1.##(16\cdot1.007276)+(18\cdot1.008665)+(16 \cdot0.000549)=34.28117## 2.##34.28117-33.9678668=0.3133032## 3. 1 atomic mass...
  6. M

    I X bjorken for binding nucleon

    Hello, I have been looking into x bjorken variable, which is definied as $$x = \frac {Q^2} {Q^2 + W^2 - M}$$ But this expression is only validate on free nucleon, I would like to know what is the expression for binding nucleon. Thanks.
  7. A

    I Question about gluons and nucleon binding

    The strong force is mediated by gluons which bind quarks together to make protons and neutrons but extends some distance outside the proton, neutron particle boundary and is said to hold nucleons together to form the nucleus. proton electrostatic charge and the electrostatic force tries to push...
  8. S

    Correct statement regarding the graph of binding energy per nucleon

    Option A is correct because the graph increases sharply at lower nucleon number Option B is correct because higher binding energy per nucleon means more stable Option C is correct because either fusion or fission will bring the product to Q So my guess the answer is D but I do not understand...
  9. A

    B The difference in the binding energy per nucleon

    if binding energy per nucleon is proportional to the number of nucleons in the range of the nuclear force. then why is the binding energy for carbon 12 higher than nitrogen 14
  10. S

    Total Angular Momentum of an odd-parity shell-model state

    Homework Statement A certain odd-parity shell-model state can hold up to a maximum of 4 nucleons. What are its values of J and L? What about an odd-parity shell-model state with a maximum of 6 nucleons? Homework Equations Parity = (-1)L J = L+S Total angular momentum, J, is equal to orbital...
  11. S

    I Difference between parallel and antiparallel spins?

    What is the difference between parallel and antiparallel spins for a pair of nucleons? My understanding is that nucleons have a strong tendency to pair - proton with proton, neutron with neutron, proton with neutron. When they pair their spins either: cancel (spins pair antiparallel) pairing...
  12. S

    I Values for the spin of a nucleon

    Protons and neutrons are nucleons. The spin of a nucleon is it’s intrinsic angular momentum. Spin has no classic analogue and does not mean the particle is spinning on its axis. It’s an intrinsic property of the nucleon. Protons and neutrons are fermions and have spin quantum numbers of 1/2...
  13. Phi6er

    A What is the value of the pion-nucleon coupling constant?

    Links for context: 1. https://en.wikipedia.org/wiki/Yukawa_potential 2. https://en.wikipedia.org/wiki/Yukawa_interaction#Classical_potential I'm working on my BSc right now and I'm solving the energies of 2 nucleon systems (so basically just deuteron) by treating them as non-relativistic two...
  14. N

    Variation of mean momentum of a nucleon with the mass number....

    Homework Statement How to determine variation of mean momentum of a nucleon with the mass number A of nucleus? Homework Equations R=R_0A^(1/3) The Attempt at a Solution Can't find a solution with elementary approach.
  15. B

    I Neutron/proton nucleon destruction by acceleration

    A nucleon that consists entirely of two or more protons, would be accelerated evenly, as each proton would see the same force (barring any collisions or other extraneous events.) Each should experience the same force of repulsion or attraction that is causing them to accelerate, so they should...
  16. Ken Gallock

    I Wick's theorem and Nucleon scattering

    Hi. My question is about nucleon-nucleon scattering. In David Tong's lecture note, he discusses Wick's theorem and nucleon scattering (page 58-60). My problem is that I don't know how to calculate the second line of eq(3.48): \begin{equation} <p'_1, p'_2|:\psi^\dagger (x_1) \psi (x_1)...
  17. A

    B Split an atom into each and every nucleon

    Has anyone ever tried to split an atom up into each of its individual nucleon? If not, what's the closest anyone has come to? For example, if Uranium has 238 nucleons, has anyone ever tried to split it up into each and every last proton and neutron? Can anyone even do it for a light element like...
  18. victorhugo

    I Q: Binding energy per nucleon & energy released in reaction

    EDIT: I figured out what I'm stuck on is WHY do nuclear reactions favor the a reaction such that the product has a HIGHER binding energy per nucleon? Also how is energy released in a fusion reaction if the product requires more binding energy per nucleon? I need an explanation... "The graph...
  19. carllacan

    I Diagrams for nucleon scattering

    According to Tong there are two Feynman diagrams for nucleon-nucleon scattering in the interaction of the complex and real scalar fields, but I can draw another diagram where the p1 and p2 particles enter a vertex and the p1' and p2' particles go out of another vertex (linked to the first one by...
  20. J

    A Form factor and new EFT operators for a WIMP on a nucleon

    Hi, On the third paragraph(right column) of page 1 of the paper, http://journals.aps.org/prc/pdf/10.1103/PhysRevC.89.065501 , It says on form factor, "Because the momentum transfer in the scattering is large compared to the inverse nuclear size, form factors are generally included ". I...
  21. Clever Penguin

    B Atom Emission: Neutron or Proton?

    Is it possible for an atom to emit a neutron or a proton?
  22. G

    B Binding Energy per Nucleon trend for fusion vs fission

    Hello all! In my Nuclear Power assignment I decided to analyse this graph: I mention that "The difference in atomic mass and binding energy per nucleon for deuterium and helium (fusion elements) is ≈3u and 5.96 MeV respectively. However, for all elements past Iron (fission elements) the...
  23. H

    Binding energy per nucleon and fission/fusion

    Homework Statement Ok so i know that the binding energy per nucleon inceases after fission and fusion and the difference in the binding energy is given out as energy. But if the binding enrgy increases shouldn't there be energy taken in(rather than given out)? Also why is the net loss in my =...
  24. D

    Binding energy & energy required to remove a nucleon

    Homework Statement lets's say the binding energy of 2_1 deuterium atom is 2.00MeV .. what's the energy required to remove a nucleon from the 2_1 deuterium atom Homework EquationsThe Attempt at a Solution the ans is 2.00MeV... why not 1.00MeV ?? because eneryg required to remove a nucleon is...
  25. D

    Energy Req'd to Remove Nucleon from 12_6 C Atom

    Homework Statement lets's say the binding energy of 12_6 C atom is 2.00MeV .. what's the energy required to remove a nucleon form the 12_6 C atom Homework EquationsThe Attempt at a Solution is it 2.00MeV or 2.00MeV / 12 ? binding energy is defined as the energy required to separate all the...
  26. A

    The finite size of the nucleon

    Hi, I read in article: to incorporate the effects of the finite size of the nucleon, we considered an exponential form factor. I want to know what does "the finite size" mean? thank you
  27. G

    What is the average transition time for a nucleon between protons and neutrons?

    I know that the nucleus can be considered a bunch of particles that constantly transition between protons and neutrons due to exchange. Given that, is it meaningful to talk about the "average" time that a nucleon spends as either a proton or a neutron before switching to the other? Or is that a...
  28. tom.stoer

    Hamiltonian formulation of QCD and nucleon mass

    Hello, there are several papers on QCD in Hamiltonian formulation, especially in Coulomb gauge. Unfortunately the Hamiltonian H is rather formel and highly complex. Question: is there a paper discussing the contribution of individual terms of H to the nucleon mass?
  29. E

    Quantum Mechanics: Nucleon Bound Energies

    I was reading my quantum mechanics text and I have a doubt. I have the energy levels well defined for the finite square well and the author suddenly compares (I believe) those levels with the levels of the nucleon with the following phrase: "is the spacing between levels on the order of MeV for...
  30. A

    Electron scattering: nuclear radius to nucleon number relationship

    Hi! I am extremely confused on what seems to be quite a simple question. The question contains a graph of root mean square radius <r^{2}> plotted against A^{1/3} where A is the nucleon number. In the lecture notes he specifies that <r^{2}> is not the same as R but does not really say...
  31. A

    Average Binding energy per Nucleon

    What is the Average/mean binding energy per nucleon of the whole periodic table/of all the elements, considering the most naturally abundant isotopes of each element? I tried googling it a couple of times but i could not arrive at a satisfactory answer.
  32. M

    Nucleon Constituents: Virtual Quark Types

    I understand that nucleons (protons and neutrons) consist of 3 valence quarks and a sea of other stuff, virtual quark-antiquark pairs and gluons. Question: are the virtual quarks only up and down or may there be heavier quarks?
  33. F

    What is the Binding Energy per Nucleon of 238U in MeV?

    Homework Statement Find the binding energy per nucleon of 238 92 U in MeV Homework Equations ΔM= ideal mass - atomic mass Ebind= ΔM * 931.5 The Attempt at a Solution first i found the diference in mass from ideal weight and atomich weight which is 1.98499. then i multiplied...
  34. F

    Nucleon, Mass, and Atomic number

    What is differences between the definition of.. Nucleon number, atomic number, and mass number. Is there any differences as i knew that those three symbol is A. am I right?
  35. F

    How are Pions Produced in Nuclei?

    How are Pions produced inside a nucleus? I've heard it was through gluons exchange but found nothing about it.
  36. A

    Nucleon in Inifinte Square Well

    Homework Statement Assuming an infinite square well of radius 2.8E-13cm, find the normalized wave functions and the energies of the four lowest states for a nucleon. 2. The attempt at a solution I want to say that the wave function is \psi (x) = \sqrt{\frac{2}{a}} sin(\frac{n \pi}{a} x)...
  37. L

    Why is the binding energy per nucleon lower for lighter nuclei?

    From the graph plotted between Mass Number and Binding Energy per Nucleon, we infer the BE/A is stable for mass numbers between 20 and 60 (approximately) and decreases for A>60. Similarly the BE/A is very less for lighter nuclei, say, Helium. Nuclear forces are short range forces. So it is...
  38. E

    Why does the magnetic moment of a nucleon line up with a uniform magnetic field?

    I thought the external magnetic field had to vary within an object in order for that object's magnetic moment to line up with the field.
  39. A

    DeBroglie wavelength and nucleon velocity

    Homework Statement Atomic nucleus consists of nucleons. What velocity (order of magnitude estimate) will a nucleon have inside a nucleus? Homework Equations \lambda = h/mv v = h/m\lambda The Attempt at a Solution The wavelength of a nucleus is on the order of 10^-15/m...
  40. K

    Why Are There No 3 Up Quark Nucleons?

    There are four Delta particles made up of down and up quarks and having spin 3/2, but there are only two nucleons, the proton and the neutron. Why are there no particles made up of three up (or down) quarks and having spin 1/2??
  41. D

    Calculating Average Binding Energy per Nucleon in Deuterium

    Homework Statement Calculate the average binding energy per nucleon in the deuterium nucleus. Homework Equations Average binding energy= total binding energy/mass number The Attempt at a Solution Would i first have to find the mass of the nucleus and then the difference in mass? My...
  42. M

    Physical origin of nucleon pair-breaking energy?

    I have to give a brief presentation on the evidence for pairing in atomic nuclei. One of the items of evidence I will talk about is the difference in binding energy between even-even and odd-odd isobars. For instance, here I have plotted the atomic masses of a range of even-A isobars A = 40...
  43. P

    Any application of AdS/CFT to nucleon structure?

    AdS/CFT has primarily focused on quark-gluon plasma, but I notice some people are trying to apply the idea to bound states such as baryons. How much progress has been made in this field? Is it possible for AdS/CFT to shed light on problems such as parton distribution functions and proton spin...
  44. C

    How Do Binding Energies Compare Between Nucleons and Electrons in Deuterium?

    Homework Statement a) Calculate the average binding energy per nucleon in the deuterium nucleus. b) The energy that binds an orbiting electron to the hydrogen nucleus is 13.4eV. Calculate the ratio of the binding energy per nucleon to the binding energy per electron in deuterium. Which...
  45. J

    What is the formula for calculating Kmin of a nucleon and how can it be proven?

    Homework Statement Kmin of a nucleon is given by the expression K_{min}\approx 3(hbar)\pi ^{2}/2ma^{2} if a\approx 2R_{0}A^{1/3} and R_{0}=1.07 fm prove that K_{min}= 133Mev/A^{2/3}Homework Equations I used hbar=h/2\pi The Attempt at a Solution after plugging it all in I get...
  46. H

    Do electrons lose mass due to revolving around nucleon?

    Does the nucleon and electron lose mass as a result of the energies they exert in a static state. The electron constantly uses the electromagnetic force to keep it attracted to the nucleon causing it to revolve around the nucleon. So does it lose mass? Similarly, does the nucleon lose mass...
  47. S

    Proving 8Be Ground State Stability vs Nucleon Emission

    Homework Statement The question is longer than this but the part I'm stuck on is this - Show that the ground state of 8Be is stable against nucleon emission. Homework Equations I'm not sure which ones to use... I used the binding energy formula. The Attempt at a Solution what I'm...
  48. K

    Exploring Decrease in Binding Energy per Nucleon in Heavy Nuclei Like U-235

    Homework Statement . Why does the binding energy per nucleon decrease with increase in mass number for heavy nuclei like 235 U? Homework Equations The loss in energy of the nucleons when they move from an unbound state to a bound state is the binding...
  49. K

    Binding energy per nucleon for atoms of low mass number

    Could someone please explain to me as to why the binding energy per nucleon is lower for atoms of low mass number as compared to the atoms in the middle zone of the binding energy per nucleon versus mass number graph? My conceptual issue lies in the fact that when the mass number is low the...
  50. E

    Gravitational force of one nucleon

    It is supposed that the smallest posible black hole has mass of Planck's mass. But obviously one nucleon (or an electron) also acts with gravitational force. If we assume that the smallest possible black hole has really Planck's mass, is here any contradiction that nucleon acts with...