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 there spectra that "prove" that measured energy excesses came purely from deuterium-tritium fusion reactions at the NIF during ignition events?
More energy was produced than was supplied by ultraviolet (UV) lasers (creating x-rays in the gold chamber wall to compress the spherical hollow capsule creating a dense, high-temperature, high-...
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Where can I find accurate visual representations of atomic nucleus nucleons wave probability functions like I see for electron atomic orbitals?
Note the Wikipedia article for 'Atomic nucleus' was awkward here because first they depict the old concept with protons and neutrons as a bunch of spheres touching each other and in the sub-text ...
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How to use point-kinetics approximation to go from diffusion to point kinetics?
I understand that we get to point kinetics by neglecting spatial dependence in the diffusion equation, but I'm somewhat stuck on the details here. Robert E. Masterson's Introduction to Nuclear Reactor ...
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Does free neutron decay create a hydrogen atom?
When a free neutron decays, it is transformed into a proton, an electron, and a neutrino. Does this electron begin to "orbit" the proton, forming a hydrogen atom? Or does the electron run ...
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Sensitivity of different elements to neutron activation analysis
When I look at Ortec AN34 Experiment 17, I see that the last page shows relative sensitivity to Neutron activation by weight for different elements. For example, the analysis of Fluorine is shown as ...
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Is a neutron the mixture of a proton and an electron?
Is a neutron a combination of a proton and an electron either by mass and/or charge?
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How does QED describe the electromagnetic scattering between two neutral fermions?
Fermions with no electric charge may carry magnetic moments e.g., the neutron. Since particles with magnetic magnetic moments interact, they're expected to scatter off each other electromagnetically. ...
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What is the significance of the Strong interaction between a pair of Neutrons?
When we are introduced to the Strong Nuclear force, we are told that it prevents the nucleus from flying apart because of the electric repulsion between protons. But there is no such repulsion between ...
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Could lithium deuteride sustain a "cold" chain reaction?
When Lithium 6 absorbs a neutron (thermal or not) it reacts forming an alpha particle and a tritium. The formed tritium has an average kinetic energy of 2.5 MeV. That kinetic energy is way higher than ...
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The difference between neutron and proton separation energy of a nucleus
For a given nucleus, why does the value of the neutron separation energy $S_n$ differ from the value of the proton separation energy $S_p$? One of the reasons that is immediately obvious is that the ...
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Can the neutrons in a nuclear reactor be collimated?
N.B. I am not a physicist.
My layman's understanding of a nuclear reactor is essentially that neutrons are doing one of 4 things at any given time in the reaction chamber:
Flying freely around.
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For Fermi's CP-1 experiments, why didn't they use much smaller slugs of natural uranium?
The Chicago Pile experiments used natural uranium slugs that were ~1.5 inches in diameter. The slugs were surrounded by graphite to slow down the naturally occurring neutrons to be able to affect ...
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Why do some nuclei decay by Neutron Emission?
Alright so I am confused somewhat about Neutron Heavy Nuclei not decaying, or more specifically why it is that Neutron Heavy Nuclei sometimes decay by emitting Neutrons.
Someone has already answered ...
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Is this Why a Neutron can Decay Into a Proton, Electron and Electron Antineutrino?
A neutron is udd, then an u-anti-u starts to exist close to the neutron. Then the one d and u change places forming an uud (proton) and anti-ud which decays to an electron and electron-antineutrino. ...
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Improved estimate of density of free neutrons in solar core
In an answer to this question:
Free neutrons in the sun's core?
I made a very rough attempt to estimate the density of free neutrons in the solar core. There is some non-zero rate for production ...
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Do electrons define the element? [closed]
In a nuclear reaction, protons and neutrons are exchanged and the resulting elements have a number of different protons and neutrons that uniquely define the element that we are studying.
However, can ...
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How is the Neutron capture cross section of Xenon-135 so high?
Xenon-135 has a Neutron capture cross section of 2-3 million barns, this is equivalent in area to a disk with a radius of 8-10pm. The cross sectional area of a Uranium nucleus is roughly 1 barn. The ...
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Potential yields of Np-237 using a synchotron
U238 releases a neutron when it is exposed to photons of around 11 MeV, and the resulting U237 promptly decays into the fissile Np237.
In such a situation, what equations can I use to relate the ...
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$\beta^{+}$ and $\beta^{-}$ decay processes
We know that electron cannot exist inside the nucleus for various reasons like its energy, angular momentum violation and etc. But these $\beta^{+}$ and $\beta^{-}$ processes occurs inside the nuclei ...
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Has Anti-beta decay been observed?
I am looking for references or resources regarding the transition of an anti-neutron through weak decay, into an anti-proton, positron, and electron-neutrino.
Have such studies been conducted or ...
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Why the Fermi's energies of the proton, neutron and electron are related in this way in a neutron star?
I'm referring to this answer made by ProfRob about why neutrons are stable against beta decay in neutron stars.
I've partially understood the answer: when the Fermi's momentum of the electron $p_f = (...
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Refractive index of EM waves travelling though a gas of neutral particles
From what I have read and seen online. The explanation of why there is a net reduction in the speed of EM waves through a medium is due to the interference with the oscillating EM fields produced by ...
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In a fission reaction mass is converted to energy my students are asking where the mass is taken from - do the nucleons have less mass afterwards? [duplicate]
I am teaching year 11 Physics for the first time. In a fission reaction mass is converted to energy my students are asking where the mass is taken from - do the nucleons have less mass afterwards?
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Spallation neutron sources + wakefield particle accelerator + U-238 for generation of Pu-239 [closed]
I am looking to combine the principles of spallation neutron sources, wakefield particle accelerators, and neutron absorption to enable anybody to create large amounts of plutonium using relatively ...
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Can Neutron Activation Analysis differ isotopes?
I know to carry out an NAA analysis, the specimen is placed into a suitable irradiation facility and bombarded with neutrons. This creates artificial radioisotopes of the elements present. Following ...
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Is it possible to collide two neutrons? [closed]
If it is possible to collide two neutrons, how is it so? What particle accelerator or pre-collision processes are necessary and what results can be expected? If the products of neutron-neutron ...
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Is an electron more stable than a proton/neutron?
Is an electron more stable than a proton/neutron under extreme temperature/pressure conditions, like several 100 millions K?
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Stacking of magnetic moments in a polarised neutron beam
Neutrons are particles that have a half spin and a magnetic moment. if you polarise a beam of neutrons so that they all align with spin +1/2 will the combined neutron beam have an overall magnetic ...
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How electron, proton and neutron have mass numbers
As far as I know, the mass number of an atom means the amount of protons and neutrons it has. For example, the mass number of Sodium (Na) is 23 since it has 11 protons and 12 neutrons. Then how ...
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Why are nuclei with large numbers of neutrons only stable with correspondingly large numbers of protons? [duplicate]
Large numbers of protons need to be separated by neutrons, otherwise they repel....
But why do nuclei with large of numbers of neutrons only remain stable with a relatively, correspondingly large ...
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Fast neutron scattering in a neutron cloud
Will a 200 MeV neutron emitted into a neutron cloud undergo similar scattering interactions as one that is emitted into a water moderator with the resulting decreases in energy?
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Doppler broadening and Voigt profile
The shape of an isolated neutron resonance at incident neutron energy, $E_{R}$, can to first-order be represented by the single-level Breit-Wigner (SLBW) formalism, which is equivalent to a Lorentzian ...
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Why is water a good neutron absorber?
I've seen this question asked multiple times, and the answer is never detailed. I initially assumed that either hydrogen or oxygen had relatively large neutron absorption cross sections, however that ...
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Can sub-uranic elements produce a nuclear explosion if they are exposed to an extreme neutron flux? [closed]
I believe that the gun-type nuclear bomb dropped on Japan used a neutron flux generator to help its uranium go critical.
I also believe that while sub-uranic elements can undergo fission, they always ...
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Neutron star vs. Islands of stability
"Neutron stars" are said to be almost entirely composed of neutrons. The islands of stability principle recognizes an upper limit to the number of neutrons that can be introduced to an atom. ...
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Does this experiment put an end to Copenhagen (and all epistolar) interpretations of QM?
The article from April 2022 in PhysRev Research is about the famous double slit experiment (Mach Zehnder variant) made with single neutrons and it proves that there is definitely something in both ...
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Question on finding nuclear ground state spins using shell model
So I'm studying the shell model and I understand where the individual nucleon energy levels come from (Woods-Saxon plus spin-orbit interaction), but I'm stumped on how to find the ground state total ...
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Can Quarks and Gluons Escape from Protons and Neutrons?
An answer to a related question described protons and neutrons as made up of a "sea of quarks, anti-quarks, gluons, ...." with a net makeup to provide either a unit charge or no net charge. ...
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Nuclear fusion reactors and neutrons
The majority of energy produced by nuclear fusion is harnessed by neutrons or protons that split out from the product.
Given the dominant fusion method today is Deuterium + Tritium which produces He ...
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Conversion of Reich-Moore resonance parameters to neutron cross section?
For the Single-Level Breit-Wigner (SLBW) formula, the peak resonant neutron cross section is related to the total width, $\Gamma = \Gamma_{(n)} + \Sigma_{r}\Gamma_{(r)}$, reported as GT in ENDF. For ...
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How can there be superconducting protons and neutrons inside an incredibly hot neutron star?
It is hard enough for me to try to wrap my head around the idea of superconducting particles other than electrons (especially neutrons!), ....
Given the insanely hot temperatures inside a neutron star ...
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Do the free neutrons in a neutron star sometimes decay and immediately re-form?
Is there any way of confirming this, one way or the other? Would it affect any of the star's 'observeables', so to speak?
I know that two similar questions are up on Stack Exchange-physics, and I ...
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How hard is disabling nuke by making it go fizzle with neutron radiation?
Suppose we would turn on nuclear reactor without shielding next to missile silo. Would it be able to protect silo by making incoming warhead fizzle out at reasonable distance?
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Looks like it is ...
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Why can protons and neutrons be close together in a nucleus despite the uncertainty principle?
Vol II, Chapter 1 of the Feynman Lectures explains why negative electrons do not get closer to the positively charged nucleus despite the great attractive force:
If we try to confine our electrons in ...
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Do Neutrons Have a Charge Radius?
The radius of a proton is described as a "charge radius", about 0.84 fm. The neutron is about the same size, 0.8 fm, but has no measureable charge. Is this a contradiction? Are the two ...
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If electron fails to get into the lowest energy orbit after neutron decay does it remain bonded to the proton?
I have read this on Wikipedia:
A very small minority of neutron decays (about four per million) are so-called "two-body (neutron) decays", in which a proton, electron and antineutrino are ...
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Are neutrons and protons stable inside atomic nuclei?
Some people naturally assume that atomic nuclei are made of protons and neutrons. That is, they are basicly clumps of protons and neutrons that each maintain its separate existence, like pieces of ...
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Gravity affects neutrons
A long time ago I asked whether gravity affected subatomic particles. An experimental physicist kindly explained that it's known to affect neutrons. Get a neutron source, and send a beam of neutrons ...
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Is diamond a good neutron moderator?
The title mostly says it: Is diamond as a material a good neutron moderator for nuclear fission reactors?
Or: Could you build a nuclear fission reactor with diamond as a moderator, instead of graphite....
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Do neutrons change their wavelengths when diffracted?
Both neutrons and X-rays are used in diffraction. In XRD, the diffracted beam is of the same wavelength of the incident beam. The reason is that X-rays are EM waves which cause electrons to vibrate. ...
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