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2
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0answers
29 views

How large should an optically large fusion reactor be?

This is just theoretical consideration. I expect that size of the reactor would be impractical to build on Earth, but I'm interested how much. EDIT: perhaps it could be good for some huge spacecraft ...
1
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0answers
27 views

What is the equation for the pressure at which neutrons can no longer be supported by neutron degeneracy pressure?

What is the equation for the pressure at which neutrons can no longer be supported by neutron degeneracy pressure? At which point they would collapse into each other. There seems to be one for ...
3
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2answers
510 views

What experiment(s) have or can refute the existence of an electron-particle “system” over the separate existence of a neutron within itself?

This question actually came about from a discussion of another question posed here The neutron is known to be comprised of an electron and a proton, and there are observations that the neutron can be ...
1
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3answers
97 views

Why U235 over U238?

There are 3 isotopes of uranium that can be found in nature[1]: U234, U235 and U238. For a chain reaction to last there must be a high amount of neutrons contents and by comparison, U238 contains 92 ...
-2
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0answers
33 views

Why doesn't a nuclear reactor's filament deform?

Why doesn't a nuclear reactor's filament deform? The filament in the core of a nuclear reactor is usually made of uranium rods. So in the nuclear reactions the neutrons constantly move from filament ...
5
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1answer
841 views

Can Dark Matter just be clumps of Neutrons

I was wondering about Dark matter, and it occurred to me that why could it not be just nuclei of Neutrons with no electron cloud. Is it possible for such things to exists. Can Neutrons bond to one ...
0
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1answer
68 views

Why can “slow” neutrons trigger fission?

My understanding of nuclear fission is that some massive isotopes such as uranium-235 are unstable and when split via fission there will be a "slow" neutron. This slow neutron will hit another ...
0
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1answer
23 views

Alpha particle in vacuum

Does the alpha particle travel in vacuum for ever and ever or can it undergo some transformation eg two protons get separated or the neutron decays etc.?
3
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2answers
209 views

Why are neutron absorption cross sections high at low incident energy?

For example, U-235 fission cross section looks like this: As I understand it, the resonances peaks correspond to discrete quantum states of the excited compound nucleus. As you go higher, the ...
2
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2answers
40 views

Free Neutron Decay as an Energy source

I suspect there would be enormous engineering and practical difficulties using free neutron decays as a energy source (more as a battery than a net energy supplier) but assuming those could be ...
0
votes
1answer
34 views

How long remains a boron control rod?

I was wondering today, how long boron control rods remains in a nuclear power plant? When a boron atom absorbs two neutrons, it becomes the unstable isotope boron-12 and and the boron nuclei starts ...
2
votes
2answers
58 views

Why are the neutron and proton masses nearly equal? [duplicate]

The neutron to proton mass ratio is nearly one. Is there some fundamental reason from this or this simply a coincidence?
1
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2answers
81 views

Is there a maximum number of neutrons of an isotope?

I wondered whether there is a maximum number of neutrons in an isotope. Or is there no maximum number? So, can an H-75 atom exist?
0
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1answer
42 views

Scattering of slow neutrons

I've here a spectrum which was obtained from the scattering of slow neutrons on uran. But I'm not sure what I'm actually see there. Can someone explain the "scattering of slow neutrons"? Edit: ...
1
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1answer
57 views

Is there a repulsive force between neutrons at all distances or just real close?

With particles of the same charge there is a repulsive force at all distances and physicists talk about neutrons repelling each other. Does this repulsion occur at all distances like with charges ...
2
votes
3answers
101 views

Why do neutrons decay after 6 minutes?

If I understand correctly, Beta decay only occurs when an atom (or in this case subatomic particle) is unstable. Are neutrons consider unstable? If so why? And if they are not unstable is there is ...
1
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1answer
56 views

Is it possible to calculate neutron half-life theoretically?

Is it possible to calculate neutron half-life theoretically? For example, from lattice QCD or something?
1
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0answers
25 views

Can the half-life of a free neutron be calculated or is it just empirical? [duplicate]

Everyone keeps telling me its just 10.3 minutes and no one knows how to get that number form theory. Any idea?
2
votes
2answers
272 views

Why are neutrons present in an atom? [duplicate]

I have a very stupid question perhaps, but please answer me. An atom consists of electrons, protons, neutrons. protons are positively charged and electrons are equally negatively charged. The charge ...
1
vote
1answer
181 views

Neutrino-Neutron Interaction Feynman Diagram (W Boson Direction)

I am currently studying differential cross sections for my Nuclear Physics module. I'm looking an experiment where muon-neutrinos are interacting with nucleons in a scintillator producing muons (which ...
3
votes
3answers
112 views

The role of W bosons in the weak nuclear force and beta decay

I am a beginner Physics student and I am studying the weak nuclear force and how particle interactions work. Now, from my book and the Feynman diagram, I learned that a neutron can change into a ...
1
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1answer
137 views

How to calculate scalar neutron flux

I am really confused about the difference between flux and scalar flux. I have a specific question: If we have a parallel neutron beam of strength $\phi_0$ given in neutrons/cm$^2$s, incident on a ...
3
votes
4answers
149 views

Can neutrons be synthesized purely from protons and electrons?

Can neutrons be synthesized purely from protons and electrons? Note: I'm looking for reactions that do not require neutrinos or any particles besides just protons and/or electrons as reactants.
1
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1answer
110 views

How the neutron magnetic moment was measured?

How was the neutron magnetic moment measured? Was the antineutron magnetic moment measured too?
6
votes
2answers
336 views

How detectors in particle colliders can differentiate neutrons from antineutrons?

Their mass is the same. None of them interacts with EM fields. And their decay (around 1000s) is far too slow to see their decay products yet in the detector. How is it then possible to differentiate ...
0
votes
1answer
68 views

What is a Hulten potential?

What is the Hulten potential? When is it used? How is it derived? I vaguely heard about in the context of neutron synthesis / quantum mechanics. thanks
1
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3answers
530 views

Anti-neutrons, anti-quarks, isospin: What is observed and what is derived?

I would be a little more restrained with the existence of antineutrons. First at all - if I understood right - the existence of antiquarks is hypothetical. If one not agree with this please refer to ...
31
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5answers
3k views

How is it possible to accelerate a neutron?

It is possible to accelerate a charged particle in an electric field, how is it possible to accelerate a neutron? How can we control its velocity?
0
votes
1answer
68 views

If one is talking about antineutron production, what is the charge exchange?

In this question was given the antineutron production in the way $$ p + \bar{p} \rightarrow n + \bar{n}. $$ Internet search gives one source only where the charge exchange is mentioned. They talk ...
0
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1answer
79 views

How to create antineutrons?

Creating a beam of antiprotons allows to create antineutrons by charge exchange. How does this exchange work? The question pops up after the question "Is there a strong evidence of antineutron ...
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2answers
172 views

Is there a strong evidence of antineutron existance?

Wikipedia explains: The antineutron was discovered in proton–proton collisions at the Bevatron (Lawrence Berkeley National Laboratory) by Bruce Cork in 1956, one year after the antiproton was ...
-2
votes
2answers
114 views

Is neutron decay a purely electromagnetic phenomena?

Until reading the Phys.SE post here about the neutron decay I never feel strange the fact about the antisymmetricity of this decay. But indeed why this decay is antisymmetric. The neutron is his own ...
1
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3answers
255 views

Experiment demonstrating interference patterns of neutrons

The question is about experiments (and references) that demonstrate interference patterns of neutral (chargless) particles (fermions), especially neutrons. Like double-slit experiments for neutrons ...
8
votes
1answer
64 views

What happens to Cosmic Ray Neutrons at the Earth?

When Cosmic Rays fall down from the sky, they produce lots of neutrons. They are "added" to the Earth system, so what is happening to them? Do they decay to protons? It would follow that they then ...
5
votes
1answer
215 views

What is the dominant interaction between two neighboring neutrons?

Suppose they are held 10 nm apart. What is the dominant interaction between them? The magnetic dipole interaction or something else?
2
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0answers
181 views

Why is free neutron unstable but free proton is stable?

Aren't they basically made up of the same stuffs (quarks) in almost the same configuration?
1
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1answer
62 views

Will an anti-neutron annihilate a regular neutron even though they have no charge

Since neutrons have no electric charge will an anti-neutron annihilate when it comes into contact with a regular neutron as protons and anti-protons do? if so what causes it to annihilate?
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1answer
91 views

Energy dependent cross sections for neutrons

Do you know where I can find a table with energy dependent cross sections for neutrons? Thanks!
0
votes
1answer
25 views

Can an inhomogeneous magnetic field be built to slow down and catch a neutron?

Neutrons have a measureable magnetic dipole momentum from their intrinsic spin. Is it possible to slow down and catch the neutron by imposing a force by an inhomogeneous magnetic field. I think the ...
1
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0answers
24 views

How does beta+ decay actually occur? [duplicate]

I'm having difficulty in understanding beta plus decay. How can a proton which has slightly less mass than neutron transform into a neutron, positron and neutrino? Form where does the extra mass for ...
2
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3answers
60 views

Do molecular bounded systems shield or reduce neutron cross-sections?

When talking about neutron cross-sections, literature is usually investigating isolated cases of Neutron + Atom. Here, the abundance of hydrogen is dominating neutron fluxes through material. I ...
0
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0answers
58 views

Compare Dynamics of Cosmic Ray Neutron Radiation

Examining cosmic ray neutron radiation near ground by neutron monitors for example (http://www.nmdb.eu), different stations show similar dynamics in the signal. At one station, I like to "substract" ...
4
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2answers
195 views

Catching/harvesting neutrons

This question has several parts. How does modern science catch free neutrons that are just floating around? Is there anyway to "pull" a neutron off any atom that does not involve our current ...
0
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0answers
89 views

Is that true that neutron activity on Earth in 2013 is unusual?

I have just read curious statement on this website: http://www.trinitas.ru/rus/doc/0016/001d/00162241.htm (unfortunately this is in Russian, but I will try to translate) "В заключение можно отметить, ...
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3answers
500 views

How would neutron matter appear to the naked eye?

Neutron matter is matter comprised entirely of neutrons, as it exists in neutron stars. Most optical phenomena encountered in everyday life, such as light reflection and spectral absorption (i.e. ...
1
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1answer
280 views

Will a moving neutron produce a magnetic field around it?

Will a moving neutron produce a magnetic field around it? I know that neutrons have no charge, so magnetic field should not be produced along it...but neutrons have a magnetic moment. So why can't ...
5
votes
1answer
244 views

What are the strongest sources of collimated neutrons and protons?

I am imagining an unusual experiment which will require intense beams of either protons or neutrons. The experiment would work better with neutrons, but neutron sources are much weaker messier so I ...
1
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3answers
307 views

Free neutrons pass through most materials but how do they damage materials?

Neutrons has no charge so they are hard to interact with materials. That's what I'm thinking. But they collide with atoms and it causes nuclear fission. And they can also be a dangerous radioactive ...
1
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1answer
143 views

How to solve the Fukushima incident?

I am trying to find out if it is somehow possible to take all this nuclear material, put it in some type of gamma chamber or blast it with neutrons to change the uranium isotopes into something ...
3
votes
2answers
2k views

What is the shielding in nuclear reactors mainly against?

I have a little knowledge about ionizing radiation and I have been confused over why nuclear reactors need these massive shields. So, if I am not mistaken, Alpha and Beta radiation are not that ...