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Can an excited nucleus capture a second neutron?

I am wondering if is it possible to have the following scenario: Nucleus captures neutron. Nucleus is excited but does not relax through decay but captures another neutron. Maybe it is possible if ...
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0answers
25 views

Bragg Scattering of Thermal Neutrons

I'm currently reviewing Bragg scattering. The particular problem below has me slightly confused on whether I'm thinking about it correctly. Questions Is the problem below referring to the kinetic ...
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0answers
17 views

Nucleon-meson interaction

Suppose interaction lagrangian between neutron-proton doublet and $\pi$-mesons: $$ \tag 1 L_{\pi pn} = \bar{\Psi}\pi_{a}\tau_{a}(A\gamma_{5} + B)\Psi , \quad \Psi = \begin{pmatrix} p \\ n\end{pmatrix} ...
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0answers
17 views

Gadolinium poisoning vs Holmium Poisoning [closed]

Question here on the poisoning used around neutron spallation sources (or reactors, or any neutron source). I use poisoning in the sense of absorbing neutrons to prevent their release into the outside ...
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3answers
346 views

Fission of U-235 produces Cs-137 along with…?

Question about Nuclear fission in general, here. If I have the fission of U-235 and I know that one of the products is Cs-137, is there a way of figuring out the other product? Should there be ...
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2answers
36 views

Fission producing Cs-137

This is I suppose quite a precise question about Nuclear fission. What produces, aside from U-235, via a fission process, Cs-137? Does any isotope of Actinium, for example, undergo a fission process ...
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1answer
40 views

Difference between scattering amplitude and scattering lenght

I'm studying neutron scattering theory and I noticed that one usually writes the scattered wave as a spherical wave: $$\psi \sim \frac{-b} {r}e^{ikr}$$ where $b$ is known as scattering lenght. From ...
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1answer
51 views

What makes neutron heavier than a proton? [duplicate]

The mass of proton is 1.672*10¯²7 kg while it is 1.675*10¯²7 kg. Both are made up of 3 quarks each. Then what makes proton lighter than a neutron?
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2answers
794 views

What is the exact function of neutrons $N(Z)$?

Has the number $N(Z)$ of neutrons in a nuclei as a function of the number $Z$ of protons been fully understood? Beside being ballast which makes the nucleus heavier, what determines the number of ...
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1answer
40 views

Ground state of 113Sn from shell model

The shell model predicts that the ground state of 113Sn with 63 neutrons would have J=5/2+. But the ground state is taken to be 1/2+. What is the reason behind that? Has it got something to do with ...
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1answer
48 views

How was the neutron's spin measured?

In 2012 it was asked, How to measure the spin of a neutral particle. I'm not sure that the answer "Neutron spin can be measured in a Stern Gerlach setup." was really carried out. So what for ...
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1answer
66 views

How do neutrons escape nuclei?

How do neutrons ejected from a nucleus gain kinetic energy if the they don't repel electrically and the nuclear force only attracts? Does it have something to do with the weak force?
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1answer
56 views

If both neutron stars and white dwarf stars can have the same mass, what determines what a star of that mass will become when it “dies”?

My understanding is that roughly 1.4 solar masses is the upper limit for white dwarf stars, and that the lower bound for neutron stars is around 1.1 solar masses. Is there any way to tell what a star ...
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0answers
27 views

Can natural gamma radiation be induced by cosmic rays?

When cosmic-ray particles like muons or neutrons impinge the ground, they get slowed down, thermalized and captured. This process is most effective when water/rain/moisture is present. Furthermore, ...
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1answer
67 views

Total energy of neutrons and protons

In a stable nucleus, are the total energies of neutrons and protons same?
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1answer
74 views

Free neutrons in the sun's core?

In the standard description of proton-proton fusion, the first step of the interaction proceeds through the unbound diproton $\rm^2He$: $$ \begin{aligned} \rm p + p &\to \rm {}^2He^* \\ \rm ^2He^* ...
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2answers
46 views

What do moles and moles of various subatomic particles gathered together look like?

I wonder whether it is even possible to find the answer. If it is impossible to find out, why? Do moles of neutrons basically look like a neutron star? If so, what does one look like? How about ...
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2answers
88 views

Does water absorb neutrons?

Water is used as a shielding material in nuclear reactors. What's its function as a shield? Does it absorb neutrons and is there a reaction between water and neutrons?
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1answer
34 views

When align the neutron's magnetic dipole moment, does moving neutron radiates?

Was performed an experiment in the past, where neutrons pass a magnetic field and their magnetic dipole moment get aligned? Was measured an electromagnetic radiation during the experiment?
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3answers
152 views

Why do only heavy radioactive elements perform fission or fusion?

Why do only heavy radioactive elements perform fission or fusion? I mean what's so special about heavy elements which makes them ideal for nuclear fission? Also why do only neutrons show ...
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2answers
134 views

Why doesn't Beta Decay violate the laws of physics?

In Beta decay, a neutron decays into a proton, and "throws out" an electron at high speed. However, this, to me, suggests that the law of conservation of mass is not being kept here. Neutrons have a ...
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1answer
40 views

Is it possible to create helium atoms by bombarding heavy water with neutrons?

If heavy water is bombarded by neutrons is it possible that any of the deuterium atoms can capture neutrons and transmute to helium atoms? I suspect the more probable event would be knocking protons ...
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3answers
380 views

How does the number of electrons and protons determine the melting point and hardness of a solid?

How does the number of electrons, neutrons and protons determine the melting point and hardness of a solid/metal? And is it possible to create custom elements which is very strong and have very high ...
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0answers
54 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 ...
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0answers
42 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 ...
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2answers
565 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 ...
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3answers
287 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 ...
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1answer
927 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 ...
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1answer
84 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 ...
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1answer
78 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.?
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2answers
424 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 ...
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2answers
45 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
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1answer
79 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
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2answers
73 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?
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2answers
126 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?
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1answer
52 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: ...
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1answer
69 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 ...
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3answers
115 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 ...
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1answer
66 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?
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0answers
26 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?
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2answers
480 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 ...
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1answer
269 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 ...
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3answers
139 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 ...
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1answer
180 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 ...
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4answers
188 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.
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1answer
149 views

How the neutron magnetic moment was measured?

How was the neutron magnetic moment measured? Was the antineutron magnetic moment measured too?
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2answers
378 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 ...
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1answer
75 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
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3answers
574 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 ...
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5answers
4k 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?