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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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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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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Why there are “missy” areas in ENDF neutron cross section (barn)/neutron energy plots for different elements?

I was looking in ENDF for neutron cross section (barn)/neutron energy plots in different elements. As i looked throw many elements, i realized that there is always an area at specific energies where ...
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Thermal or fast neutrons are used for adding neutrons to atomic nuclei?

I understand that there is difference between thermal and fast neutrons according to their energy. Now, if one wishes to add neutrons into atomic nuclei, it should be easy as neutrons are neutral, so ...
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What is difference between fast neutrons and thermal neutrons?

Recently i was reading about neutron absorption by metals. But there are always two different categorizes for thermal neutrons and fast neutrons. I don't understand what difference between them! Most ...
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Crystals thermal neutrons can pass throw without significant change in their energy

I looked online for a really long time already for crystals which thermal neutrons can pass throw without significant change in their energy. Does anyone here know which crystals have the minimum ...
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If neutronium existed out there, are we capable of observing it? [duplicate]

I know that theoretically, neutronium cannot exist. However, no work was done until now even looking for neutronim around us. So my question is that, if neutronium actually existed with some minimum ...
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Measuring the phonon dispersion at edge of Brillouin Zone?

When it comes to measuring the phonon dispersion at the edge of a Brillouin zone, why are neutrons chosen and not photons?
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Reaction of radiation with Nitrogen-14

When solar wind brings high energy neutrons into contact with Nitrogen-14, a well known process occurs yielding Carbon-14 + a proton. N14 is assumed to exist in upper atmosphere as N2 gas, but the ...
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Gluon radiation from a nucleon?

Due to the fact that neutrons and protons consist of quarks (i.e. are not really Dirac particles), their magnetic moments differ from the so-called "nuclear magneton" (i.e. the natural unit ...
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Is there any way to know how an uranium atom will get split in a fission reaction?

I have learned that uranium atom can be split in two different ways in a fission reaction. In one case it produces two neutron while in the other it produces three. \begin{align} ^1n + {}^{235}\mathrm{...
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Are there specific containers for ultracold neutrons?

Let assume i have a cup of ultracold neutrons. As ultracold neutrons have no charge or electrons, they would not feel electrostatic forces, so they would diffuse into the walls of containers made from ...
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Neutrons generator

How free neutrons with a certain kinetic energy are produced in laboratory? For example in nuclear fission $n$ free neutrons are produced, are there other methods?
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Thermal neutrons and fission

In an answer here I read: You need slow neutrons because if the neutrons are too "quick" then they scatter of the atoms instead of being captured by them. You can imagine a big lump of playdoh and ...
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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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If a neutron decays to proton + electron, and a proton can decay into neutron + positron, doesn't this mean neutron = neutron + electron + positron?

I was just watching some videos and came across beta+ radiation (when a positron is emitted). It then occurred to me, how can the following be true, given that a positron and an electron have the same ...
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Thermal neutrons in fission

I read this: These so-called fast neutrons do not cause fission as efficiently as slower-moving ones so they are slowed down in most reactors by the process of moderation. Why slowly neutrons "...
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Feynman diagram for neutron capture

I am studying experimental methods for detecting neutrons. Having recently studied QFT, I wondered if there was a way to describe this type of process through a Feynman diagram. For example for the ...
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What is Binding energy, actually?

I have read from my textbook about binding energy but it indicates two completely different ideas.I am listing them below: Definition (1): "Binding Energy : An atomic nucleus is a stable ...
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$W^-$ behavior in Neutron decay

Why does $W^-$ always decay into electron and anti-neutrino in neutron decay? Why doesn't the $W^-$ particle decay into quark-antiquark pair?
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Why does Gadolinium have the highest neutron cross section?

Gadolinium-157 has the highest thermal-neutron capture cross-section among any stable nuclide. Based on my layman's understanding of neutron capture – particularly the fact that (I assume) neutrons ...
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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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Are neutrons gauge neutral to all gauge forces?

Are neutrons gauge neutral to all gauge interactions? Neutron has mass, so it does couple to gravity. However, if we focus on the strong, electromagnetic EM, and weak forces, are there gauge ...
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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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Quantum mechanics. Scattering from step potential barrier of magnetic field

I am having trouble to think how to solve the following problem: The plane $x=0$ separates two parts of space: when $x>0$ there is homogeneous magnetic field, which induction vector $B_x=B_y=0$, ...
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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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enriched fuel in reactors

Why is it not possible to use hot neutrons and enriched fuel in reactors? It works in fast reactors where the enriched fuel is necessary. Fast hot neutrons wouldn't give energy to non-enriched fuel. ...
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How does neutron radiation affects a body? [closed]

My question involves two aspects of the same thing: how does neutron radiation affect the particles in our body. • First of all: How does the effects happen, from a quantum perspective? • Second, ...
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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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As neutrons are more massive than protons, does the Sun increase its mass while fusioning elements?

Where is the mass coming from when neutrons are produced from protons in the Sun? If a positron is made, will it possibly annihilate with an nearby electron?
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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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Matrix element for the neutron decay using the exact $SU(3)$-symmetric limit

I want to calculate the electron spectrum in the decay process $n\rightarrow p~e^-~\bar\nu_e$. The matrix element should be written in the exact $SU(3)$-symmetric limit. Could you recommend any ...
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Difference between Fuchs-Hansen and Fuchs-Nordheim model of reactor excursion?

I was using both models to fit experimental data of a reactivity insertion (more specifically, a power vs. time plot). Both models produce almost the same fit, with slight difference in peak power. ...
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How can a Boron-10 lined detector be used to determine the reactor power pulse in a TRIGA reactor?

I have a Boron-10 lined counter, how can it be used to plot a power vs time curve for a very short period large power excursion?
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Using a Neutron Poison In $D$-$T$ Fusion Reactors to Capture Neutrons

One of the major problems of the $D$-$T$ fusion reaction is that it releases a 14MEV neutron. In large numbers, these neutrons irradiate the chamber walls and wreak havoc on the metallic lattice, ...
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Why do neutron stars have such powerful magnetic fields?

The magnetic strength of these objects is too low based on flux conservation from the original star and yet too high for a composition of mainly neutrons. Is it actually due to some quantum effect?
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'Forces' enacted by hot neutrons in fusion bomb - Pauli exclusion

Are Pauli exclusion 'forces' on a neutron 100% electromagnetic (Lennard-Jones seems more acute relationship compared to electrostatic force) If so does that neutrons have two forces between them - '...
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Experimental proof for the antineutron

An answer to the question How detectors in particle accelerators can differentiate neutrons from antineutrons do not show that an antineutron measurement was successful. The answers are from 2014 and ...
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Exponential growth or decay of neutrons in fission

I am considering the derivation for the number of neutrons as a function of time, in a fission chain reaction. In the derivation I am following, let $\tau$ be the time interval between fission events,...
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Resource recommendation: high energy physics with low energy neutron beams

I have an intuition that high energy physics, i.e. studying strong nuclear force, should be accessible via low energy neutron beams because neutrons can interact with nuclei without being impeded by ...
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In the fuel of atomic bombs when does neutron fission activity begin?

Do scientists first initiate neutron activity within the subcritical masses of fuel in the lab, or are the masses already undergoing some kind of minor neutron detachment naturally, or finally, is ...
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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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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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Cold fusion with ionized hydrogen and neutron radiation

Would bombarding ionized hydrogen gas with neutron radiation cause cold fusion as the neutrons have no electrostatic repulsion to overcome therefore making it much easier to get within range of the ...
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Measuring neutron separation energy

In Introductory Nuclear Physics, Kenneth S. Krane describes neutron separation energy (page 65), and shows a list of measured values (Figure 5.2). What experimental setup is used to measure these on ...
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What is the minimum safe distance from a neutron source through the atmosphere?

Imagine there is a source of neutrons emanating from a point in space. Maintaining line of sight, how far away from the neutron source must you be to preclude neutron poisoning if the neutrons only ...
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Energy spectrum of photoneutrons

In "Radiation Detection and Measurement" Knoll considers the production of neutrons by a ($\gamma$, n) reaction such as \begin{align} \gamma + \ ^{2}_{1}\text{H} \rightarrow \ ^{1}_{1}\text{H} + n &...
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How can neutron be converted to proton and electron?

Since a neutron and a proton are made up of quarks and an electron is a lepton, how can a neutron yield an electron?
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Can there be an atomic nucleus where there are more protons than neutrons?

As far as I know, number of protons is less that or equal to the number of neutrons in any atomic nucleus. But is there any possibility that there exists a nucleus where the number of protons exceeds ...

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