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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Are neutrons an actual particle? [duplicate]

I'm a senior student in high school and we are learning about Particle Physics in Physics. I wanted to ask a question about neutrons. Is there a possibility that neutrons may not even be a particle, ...
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Why the charge of the proton does not transfer to the neutron in the nuclei?

For example, when we put two objects of +10C and +20C together and then take them apart, each of them acquires a charge of +15C. In a nucleus, the protons and neutrons are stuck together. Why is it ...
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What is the precise value of the lifetime of a neutron?

Free neutrons are unstable. It decays to proton, electron and an antineutrino via beta decay. Can we not do a quantum field theory calculation to predict the precise the decay width? Its inverse ...
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Why does the kinematic theory of diffraction for crystals predict the reflectivity will grow larger than 1?

Kinematic diffraction for perfect crystals is based on a few assumptions (neglecting multiple scattering, far field, etc.) some of which become less valid as the crystal thickness is increased. ...
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Stable number of neutrons for a given nucleus with $Z$ protons [closed]

I have been trying to derive an expression for the stable number of neutrons using the semi-empirical mass formula. I tried to derive it by dividing the Ma by total number of nucleons and then ...
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Probability of forming a proton or neutron with loose quarks?

If I had two unbound up quarks and a down quark or two unbound down quarks and an up quark, what is the probability, if I bring them close together, they stick and form a proton and a neutron, ...
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What does it mean that a neutron has a 'negative' magnetic moment?

Most questions about this ask why, or how, a neutron has a magnetic moment at all, or why it is negative.... But I am curious as to what it means, physically or experimentally, for a magnetic moment ...
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Can an electron and a proton be artificially or naturally merged to form a neutron?

My sense is that even though neutrons decay into a proton and an electron they are made up of quarks, it is not just some "merged" particle where, for example, the electron is orbiting the ...
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Do neutrons have any attractive forces with electrons as they have with a proton? [closed]

the strong nuclear force is an attractive force between protons and neutrons that keep the nucleus together and weak force is responsible for radioactive decay. also, neutrino is lepton and positron ...
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Why do neutrons have magnetic moments with spin?

Neutrons are neutrally charged, but apparently they have magnetic moments with spin. What is the intuition behind this?
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Why arent'the best neutron absorbers always the ones with the largest cross sections? Does the reaction product have something to do with it?

There used to be a question (and answer) here that mentioned why isotopes of cadmium, xenon, hafnium, etc. that have larger cross-sections than boron-10 weren't as good at being neutron absorbers in ...
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'Two neutrons as twins' paradox

Is this confusing for other people? Let pressume we can extract two neutrons from their atoms and do an experiment. At time t0 we leave one of them standing still and the other one circulate inside a ...
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Statistical argument for n/p ratio in relativistic neutrino environment?

Consider a system with high-energy neutrinos (higher than rest mass energies of protons & neutrons) where the energy of a neutrino is specified as $E = p + sB$, $p$ being the magnitude of the ...
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Nuclear beta decay to hydrogen

In reading about nuclear beta decay: $$n \longrightarrow p + e^{-} + \bar \nu$$ It occurred to me that two of the particles resulting from this decay are the constituents of the hydrogen atom. So why ...
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How do neutron stars emit black body radiation?

If my understanding is correct, black body radiation is emitted by a substance due to the substances coupling with the electric field. The negatively charged electrons in atoms for example can couple ...
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Filling order in the Shell Model of the nucleus

I have read that, in the nuclear shell model, nucleons are distributed filling energy levels following the Pauli exclusion principle. These energy levels can be designed with the $nl_j$ notation: $1s_{...
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Destroying Nuclear Waste with Neutrons?

is it possible to safely dispose of nuclear waste by bombarding it with neutrons, and if so, what energy/temperature of neutron is required? Are thermal neutrons sufficient or must they be fast? ...
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Pauli exclusion principle: why does it imply that $Z\approx N$ in stable nuclides with $A<40$?

I have read that when representing the possible nuclides in the $(Z,N)$ plot, the stable nuclei located on the line $N=Z$ for $A<40$, and that this is due to the Pauli exclusion principle. I have ...
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Can you represent neutron as stable superposition of decay products?

In this article (here) it says that unstable particles can be represented as a stable superposition of the decay products. It says this representation is most relevant for when resonances only appear ...
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Is proton easier to remove from a nucleus than a neutron?

Which factors will we consider for deciding whether a proton is easier to remove or a neutron? Considering Coulombic forces, proton experiences repulsive force and hence easier to remove. But why will ...
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Why do gamma-rays and neutrons produce different decay times in scintillation pulses from the same compound?

The basis of pulse shape discrimination is that gamma-rays and neutrons have different decay times of their electronic pulses. What makes gamma-rays and neutrons interact with the same compound ...
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Is the nucleus smaller than the electron?

In the classical incorrect 'billiard ball' model of the atom, electrons are often drawn as smaller balls than the protons and neutrons in the nucleus. However from quantum mechanics we know the ...
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Does the Electric Field Instantaneously vanish during an Electron Capture?

When an Electron Capture occurs a Neutron and a Neutrino are formed. Prior to this process due to the presence of the proton and electron an electric field must've existed however as soon as this ...
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Why do Xe-135 and Zr-88 have a surprisingly large thermal neutron capture cross-section?

Why do Xe-135 and Zr-88 have surprisingly large thermal neutron capture cross-sections? The probability that a nucleus will absorb a neutron—the neutron capture cross-section—is important to many ...
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What determines whether free neutron decay results in the production of a neutral hydrogen atom?

Free neutrons (outside the nucleus) are known to be highly unstable with a mean lifetime of around 14 minutes and 40 seconds. Inside the neutron, which is composed of 1 up quark and 2 down quarks, a ...
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Nuclide Chart: cross-section for unstable isotopes

Why is there no cross-section for neutron capture on a nuclide chart for unstable isotopes (e.g. beta-plus/minus decaying isotopes). Since there are half-lifes long enough to make measuring those ...
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In Al27 (alpha,n): why is a neutron ejected?

Why does a neutron get ejected when Aluminium-27 is hit with an alpha particle? It seems like: Al-27 + He-4 --> P-31 (stable) and a gamma/(s) as the nucleus re-arranges. So why eject the neutron ...
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How can you produce a spectrum with He3 thermal neutron detector?

I'm looking to understand how Bonner Sphere System works. I understand the whole idea, but I'm lost about how a single sphere can produce a whole spectrum. For instance with He3 thermal detector, the ...
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Pressure stabilisation of radionuclei

Looking at explanations of neutron stars, the neutrons towards the center of the star are stabilised by the enormous pressure, and so don't undergo nuclear decay. I am wondering if this is possible ...
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How can the neutron have any 'electric polarizability'?

If a neutron has no identifiable electric charge or polarization, as far as anybody has been able to determine, how can it have a value for 'electric polarizability'? Wikipedia has a value listed that ...
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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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What colour would neutronium be? [duplicate]

Everything we learn about colour in relation to matter is based on "normal" matter that has electrons around it. Absorption and emission of electromagnetic radiation is explained in terms of ...
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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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Do neutrons in a strong electric field show a small dipole behaviour?

As neutrons are neutral an electric field should not attract or repel them. However, as they are composed of a positive and a negative part, called one 'up' and two 'down' quarks, shouldn't those ...
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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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