Questions tagged [neutrons]

The neutron is a subatomic particle, with no net electric charge and a mass slightly larger than that of a proton. It is a fermion of spin $\frac 1 2$; a hadron, that is it interacts strongly; and a nucleon, that is a crucial component of atomic nuclei.

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Understanding inelastic neutron scattering intensities

Inelastic neutron scattering (INS) is commonly used to probe the magnetic structure of materials and to probe magnetic excitations (magnons) in a system. Unpolarized INS measures the spin-spin ...
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Model of a neutron composed of a proton and an electron

Is it possible to establish a model to describe neutrons as electrons and protons bound by the coulomb force? what disadvantages would it have?
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How Chadwick concluded that the particles are neutrons but not photons?

James Chadwick conducted an experiment in which he bombarded Beryllium with alpha particles from the natural radioactive decay of Polonium. How he concluded that the radiation was made up of neutrons ...
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What exactly is energy self-shielding in nuclear physics?

I have recently been trying to understand self-shielding, both energy and spatial self-shielding. I am having a particularly hard time understanding energy self shielding. Thus far, everything I’ve ...
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Why doesn't a nucleus-like body made up of just neutrons exist?

We know that neutrons exert short ranged nuclear forces over other nucleons in a nucleus, and these forces are only attractive in nature. Also this force is universal and doesn't differentiate between ...
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How are we sure that the measured proton spin puzzle will be also observed similarly in the neutron thus a neutron spin puzzle?

The EMC experiment in 1988 using muons' deep inelastic scattering, has reported that the contribution of the valence quarks triplet (i.e. up-up-down) in the proton was measured to contribute as little ...
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What would happen if someone takes a sample away from a neutron star? [duplicate]

What would happen if someone takes a sample slowly away from a neutron star? Will it gradually change to some "normal" matter with regular atoms? If so, what atomic number will they have?
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Puzzle with the precession of the neutron spin?

More perplexing news about the neutron spin in this recent Nature Physics publication: arxiv.org/abs/2103.03333 The authors collaboration (more than 100 authors) report a newly experimentally found ...
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How is Alpha Radiation possible?

Alpha radiation would seem to occur when a pair of protons and neutrons are magically plucked from the amorphous (i.e. having no particular structure) nucleus of a heavier atom. Some of the problems ...
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Can neutron magnetic moment be used to slightly deflect the neutrons to not hit the tocamac lattice at a really small angle?

Can neutron magnetic moment be used to slightly deflect the neutrons to not hit the tocamac lattice at a small angle? So part of the moment is spent to change its velocity vector orientation?
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Do neutrons fall to the center of the earth?

Neutrons have no electric charge so they don't interact with the electric and magnetic fields, have mass so they do interact with gravity and are smaller than nuclei so they pass through most atoms, ...
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Do cold neutrons produce radioactive elements?

As far as I have understood neutron nuclear reactions, if a fast neutron gets captured by a nucleus, since the kinetic energy has to go somewhere, the newly formed nucleus is radioactive and must ...
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Neutron Spin and external magnetic field

I know as a fact that neutrons have spin 1/2, as spin is an angular momentum it should couple with an external magnetic field, so that means that the neutron is interacting with B and has q=0, so iḿ ...
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Why is the neutron electric dipole term CP violating?

I have heard that a term of the form $\bar{q}\sigma^{\mu\nu}q F_{\mu\nu}$ is CP violating but looking at any Textbook (e.g. Peskin Schröder) one can see that the CP transformations are the following: $...
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Why neutron degeneracy pressure is much stronger than electron degeneracy pressure?

I am asking about Pauli Exclusion Principle stating that no two fermions can have the same 4 quantum numbers which is why we have periodic table of elements, but straight to my question: despite Pauli ...
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Selection rules in neutron scattering

Why doesn't neutron scattering have selection rules? According to Wikipedia, it seems that the value of the transition moment integral will be non-zero, but I guess another way of phrasing my question ...
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Why do neutrons begin to be emitted?

If I have a handful of 95% U235 it will be emitting alpha and beta particles and gamma radiation depending on what decay daughters are present. No neutrons will be emitted. If I pour that handful into ...
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Are "resonances" we are finding all in ground states or not?

Sometimes scientists are finding new compound particles as "resonances", i.e. short living complexes of constituent particles. For example dineutron was found as resonance with lifetime of $...
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How much energy is released during the decay of 1 kg of neutronium?

i'm trying to find out what the decay energy is for neutronium. i'd like to find out if it would be a suitable fuel source for our civilization's needs (if we ignore the problem of extracting it from ...
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Differential Decay Rate - What is wrong with my result?

I am trying to calculate the decay rate of pion in a certain BSM model. In this model the pion decays to a photon, and a pair of BSM particles $\chi_1$ and $ \chi_2$; the diagram is a pion decaying to ...
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Is there a way to calculate the so-called 'diffusion velocity' of neutrons?

I am conducting some deterministic multigroup pulsed-neutron die away simulations where the neutron diffusion equation is being solved via finite difference methods and would like a way of verifying ...
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How can we detect neutrons?

If I am asked to design a simple experiment to detect neutrons, how can I do that? The problem is, neutron is a neutral particle. So, application of electric and magnetic fields won't help. Can I ...
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Does the collision of a neutron and anti-neutron produce energy?

Following up on this post: Anti-Particle of Neutron, one very important part of it is unanswered. If a neutron collides with an anti-neutron, will it violently explode in a flash of energy? The ...
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What does the term "half life" mean for a single radioactive particle? [duplicate]

I was introduced to the term half life as the time it takes for the number of radioactive nuclei to become half of its initial value in a radioactive sample. But there is a question in "Concept ...
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Can a single nucleon undergo beta decay an infinite number of times?

Can a single nucleon (i.e., neutron or proton) undergo beta decay (+ or -)an infinite number of times? If so, how does this square vs. the principle of conservation of mass/energy? If not, what are ...
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Why is there a discrepancy between $m_n-m_p$ and $m_d-m_u$?

The difference in mass between a neutron and a proton is $1.3\space {\rm MeV}/c^2$, but the mass difference between an up quark and a down quark is $2.5\space{\rm MeV}/c^2$. How come the mass ...
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Is the nuclear binding energy of a free neutron 0?

This might be a silly question. I've always assumed that the neutron had a binding energy of 0 because it's only one nucleon that isn't interacting with any others most of the time, just like a proton....
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$n+n \rightarrow n+n$ scattering through photon interaction (QED Process)

If I think about the quark level process then, two u quarks can scatter through photon exchange via QED interaction by following tree-level process . This is happening because u quark is electrically ...
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What is the difference between the X-ray diffraction and neutron diffraction?

In the Kittel book, I have read that the ionic form of $\text{KCl}$ contains $\text{K}^+$ and $\text{Cl}^-$, having equal number of electrons. Looking at the statement in figure that while doing the ...
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Is it possible that two neutrons can merge?

At the center of neutron stars are tightly packed neutrons with almost no space between them. Also, proton and electron have all merged (electron capture) forming as much neutrons as possible. When ...
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Number of neutrons per same weight samples

I've stumbled on this question that I can't seem to figure the answer of: Which of the following 4 samples contains the least number of neutrons, considering that they all have the same mass. ...
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How do nuclear fuel rods get "spent"? Why can't you just throw neutrons at them?

The idea of fuel rods being both "spent" and dangerously radioactive has always seemed to me to be self-contradictory. The typical explanation given is that the human body and environment ...
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What is cross section?

I am learning about unit Barn, its unit of cross section. I know it means how likely a particle is to interact with material, its like opacity or transparency in optics. What I dont understand is what ...
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Can neutronium, (as in the exotic -onium atom composed of $n\bar n$ and not the degenerate matter kind) exist?

First off I'd like to say yeas I know what neutron-degenerate matter aka neutronium is and how it's likely what's inside neutron starts, this isn't what the wuestion is abount. I am referring to an -...
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How, exactly, does an electron scatter off of a neutron?

I thought about this recently because of news articles discussing the measurements of the 'neutron skin' of large nuclei.... Is it due to the fact that both have a negative magnetic moment? Or to ...
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How does a Poyinting vector act on a neutron?

How does a Poyinting vector act on a neutron? As I understood a photon action on a charged particle this action is purely electromagnetic where the electric component shake the particle perpendicular ...
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How to interpret the momentum structure figure of the inelastic neutron scattering data?

I am recently reading inelastic neutron scattering papers and I can always see figures like the one above (https://science.sciencemag.org/content/356/6342/1055). However, I couldn't understand what it ...
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Proving that neutron and antineutron are not the same particles [closed]

How can you prove that the neutron and antineutron are not the same particles knowing that neutron is not a stable particle?
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Does the electron capture process ever occur in hydrogen?

I know that electron capture occurs more readily in heavier, often unstable atoms, but does it ever happen at all in a lighter atom? I suppose, in ordinary hydrogen, a free neutron would then be ...
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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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Neutron and mass-energy

Neutrons and protons are particles and they have mass. If mass and energy is interconvertible, then, why does nucleon number have to be conserved?
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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 ...
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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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Why free neutrons are usually produced in a Nuclear Fission?

The production of neutrons is a feature of fission reaction. Usually 2-3 free neutrons are produced in the fission. Why is that so?
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What defines Fusion-Evaporation Reactions in Nuclear Physics?

A bit of a general question I know; but I would like to understand a bit more about the topic. The situation is an alpha beam is incident on an Aluminium-27 target, which ejects a neutron and leaves a ...
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What exactly is neutron radiation?

Well, I'll be honest my physics is not good. But I really wonder about radiation and other physical stuff. When I search about it I see three types of ionizing radiation: Alpha, Beta and Gamma. But ...
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Is there any conversion mechanism of neutron radiation into electromagnetic radiation?

Charged radiation such as beta, alpha or even stray protons and nuclei as they are charged can loose their energy as photons. Can neutrons do this as well, even if they do not have any electric charge ...
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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. ...
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What is the significant of Neutron in an Atom? [closed]

I'm interested to know about Neutron in an atom.This question is very difficult for me.I tried to know the answer of the question many time but I didn't find.
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Can we uniquely determine the particles emitted in a neutron induced binary fission of a radioactive element?

Can we uniquely determine the particles emitted in a neutron induced binary fission of a radioactive element? For example, if we have $ \newcommand{\U}{\mathrm U} \newcommand{\Mo}{\mathrm{Mo}} \...
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