Neutron Definition and 746 Threads

First: what precisely is the shape of delayed neutron energy spectrum for each single emitter, generally? Second: what are the delayed neutron energy parameters for the common isotopes producing them? The attested list seems to be: Br-87 55,65 s 2,52 % Cs-141 24,8 s 0,035 % I-137 24,13 s 7,14 %...

In the brilliant.org website talking about quantum properties it is said that neutrons coming from a nuclear oven and passing through two permanent magnets of opposite polarity hit a surface only at the top and the bottom of it (there is no continuity) because the spin property is quantized and...

From what I read I see that for example a radioactive nucleus is a nucleus in an excited state and when it transitions back to it's stable state (changes from one element to another due to radioactive decay) one of the ways this happens is that the nucleus emits a energetic photon with a...

Hello! I am not sure I understand how neutron coherent scattering takes place. The case I am particularly talking about is neutron scattering off a hydrogen molecule. When thinking of Coulomb interaction, I would imagine this as if the incident particle (not a neutron, as the neutron doesn't...

Here is a presentation on the discovery of two colliding neutron stars and the resulting phenomena such as gravity waves, gamma ray bursts, and synthesis of high atomic number elements. The author is a theoretical physicist who is involved in the research. He says that the neutron stars most...

Does neutron decay outside of the nucleus occur faster, slower, or at the same speed when the environment it is in is near absolute zero? Do any external factors affect the speed of a neutron decaying?

Whats the minimum kinetic energy a neutron must have in order to trigger the fission of for example a lithium core ?

Since electromagnetic radiation is emitted as electrons decay from higher to lower states of excitation, I would assume that neutron stars cannot lose energy by blackbody radiation. That would leave tidal drag and evaporation as the only ways a neutron star can lose energy...True?

I'm splitting this off the proton radius thread. The first measurements of the neutron lifetime worked as follows: you get a nuclear reactor as a neutron source and open a port in it to get a beam of neutrons. You count the number of neutrons in the beam and the number of protons (from neutron...

I read that after explosions supernovas can ”transform” into a neutron start or into a black hole? And now I’m curious of therer any factors which can predict what thing we’re going to get after the supernova’s explosion.

I have a question regarding Neutron Star cores that perhaps PF could clarify for me. Given a millisecond spinning NS, and given that its gravity decreases toward the center, being a spherical body, does centrifugal force displace the core material outwards to form an empty obloid-shaped cavity...

Does one neutron or more than one make different when they interact with the nuclei? what is the result that could happen if one neutron or neutrons hit the nuclei? I'm not sure but I think the neutrons are the most confusing particles to deal with. I wish you guys can help me Thanks

For neutron inelastic interaction, the nucleus de-excites by emitting gamma-rays or charged particles. However, for neutron capture, the nucleus de-excites by emitting gamma-rays only. Why does the nucleus in the neutron capture interaction de-excite by only emitting gamma-rays? why not by...

Hello. I'm very interested to find out more about the maximum masses of white dwarf stars and of neutron stars. Please note that while my level in this forum is Basic, I am familiar with the role that the Chandrasekhar limit has played in our understanding of white dwarves. I was therefore...

Would neutron star cores be a good system to study quantum gravity? Core densities are higher than nuclear material. Is it possible cores exhibit QG effects?

Summary: Problem: nuclear physics, neutron capture In the problem one should calculate time dependence of number of nuclei. Problem statement: Neutron beam radiates sample A with initial number of atoms N0. With neutron capture nuclei (cores) of A are transitioning to nuclei B (they are just...

Summary: hypothetical experiment, how would neutron core behave in such a circumstance such as, if we teleport 1mm^3 of neutron star core from it outside. how would the 1mm^3 neutrons behave? 1. Would it be stable/no change 2. Would it decay into cosmic radiation 3. would it decay into...

In many physics fields, the neutron is considered as a separate particle? But the neutron decays into a proton and an electron. Why is it considered an independent particle? Although the fact of decay suggests that the neutron is a composite particle.

I've been trying to understand why adding neutrons to a nucleus will eventually destabilize it; I would like to know if the following explanation is correct: The neutron has a slightly higher mass than the proton. But higher mass translates into higher energy because ## E = mc^2 ##. However...

How is neutron degeneracy pressure able to support a much higher density object such as a neutron star where electron degeneracy pressure only supports a comparatively less dense object such as a white dwarf. Conceptually I would think electron degeneracy pressure to be stronger due to the...

Is it possible for white dwarf star in binary system where it is feeding off its partner star to collapse directly into a neutron star? Or is something inherent in the formation of neutron stars where they must be formed from supernova?

Does temperature apply to subatomic particles, in particular the neutron? The question is prompted by the definition of absolute zero, being specific to atomic movement.

Hi, I'm reading chapter 6-3 of Lamarsh's book "Introduction to Nuclear Reactor Theory". Here it is discussed the very idealistic case of Hydrogen being used as a Moderator (without adsorption). The moderator is: - infinte - homogeneous - with uniformly distributed source emitting at constant...

Homework Statement Show that the neutron density distribution function at any point in a monodirectional beam of monoenergetic neutrons moving along the x-axis is given by $$n(x, \mathbf \omega) = \frac n {\pi} \delta( \mu -1)$$ where ##n## is the neutron density, ##\delta( \mu -1)## is the...

I don't understand this line in iter website. How is this reaction possible? "When exposed to the intense flux of neutrons from the fusion reaction, the oxygen present in the water generates short-lived radioactive isotopes of nitrogen—one (isotope 16) emitting a highly energetic gamma ray, the...

Hi, I did an MCNP simulation to see the neutron energy deposition in water. I used 14-MeV neutrons, and big enough water body to make sure all the neutrons stay in the water and give all their energies to water. I used F6 tally. However, I got energy deposition of around 10.3 MeV, not 14 MEV...

Homework Statement Show that when a neutron is scattered from hydrogen, the angle between the laboratory velocities of the scattered neutron and the recoiling proton is always 90°. Homework Equations Conservation of momentum (Conservation of Energy) The Attempt at a Solution This isn't a...

Hi, I'm reading Lamarsh's book "Introduction to nuclear reactor theory" and in chapter two there is a brief description of neutron scattering theory. I have a few questions about it. 1) In the book the author says that it is easier to analyze the interaction process in the center of mass frame...

Hi, I have questions on the neutron decay What prevent the neutron to decay in udc or udt except mass/energy consideration ? If we do the assumption that (udc) and (udt) have the same mass than the proton (yes I know, this doesn't make sense) the three decay (p, udc, udt) woulld have the same...

First post and I am not a scientist - just a curious soul. What stops a neutron star/magnetar from collapsing further into a black hole?

Can anyone tell me, What quantum state really is? Is it applicable for all sub atomic particles? Then, Can anyone explain how two electron are never in same quantum state. And Does proton or neutron follows the same law as electron for obtaining unique quantum state.

I where looking for elements that can absorpt neutrons without generating radioactive materials, and I found that most of them in Earth are suitable. I found that could work: C, O, Si, S, N, H The most common isotopes can receive one or two neutrons being stable, but if a neutron would be...

Suppose some protons are impacted on a Lithium target to produce neutrons with energies close to the proton energy. If one considers Energy-loss due to proton-target collision (ionization of the target atoms), will this kind of energy loss influence neutron energy spectrum? I am asked by my...

Hello, I just had a little debate with my professor after taking my final exam. He had given us an additional formula sheet at the last second (hand written on the projector) which confused me. The question was a 7 MeV neutron collides with several U-238 atoms before reaching 2 MeV. How many...

Homework Statement [1] is the one-speed steady-state neutron diffusion equation, where D is the diffusion coefficient, Φ is the neutron flux, Σa is the neutron absorption cross-section, and S is an external neutron source. Solving this equation using a 'homogeneous' material allows D to be...

I am certainly not qualified to really comment on this subject, but I have been playing around with some ideas on how to confine neutrons to the interior of a nuclear reactor. I was wondering if there was a way to capture a emitted neutron from a reaction with a selected isotope that would be...

If I am observing a pinging beacon free-falling into a neutron star from a distance far enough away that I am in approximately flat spacetime, I think I observe the pings redshifting as the beacon gets deeper into the gravity well, in other words I see the clock of the beacon slowing with...

I'm working through an introductory book on special relativity (by Resnick and Halliday), and am having trouble with one of the end-of-chapter problems. Problem Statement: Sue and Jim are two experimenters at rest with respect to one another at different points in space. They “fire” neutrons...

Homework Statement Fission, the process that supplies energy in nuclear power plants, occurs when a heavy nucleus is split into two medium-sized nuclei. One such reaction occurs when a neutron colliding with a 235U (uranium) nucleus splits that nucleus into a 141Ba (barium) nucleus and a 92Kr...

I wish to draw the proton momentum spectrum by transforming the energy spectrum of recoil protons. I have calculated the energy spectrum using Nachtmann's spectrum: wp=g1[T]+a*g2[T] Where: g1[T]=(1 - x2/σ[T])2 * Sqrt[1 - σ[T]] * (4*(1 + x2/σ[T]) - (4/3*(σ[T] - x2)/σ[T])*(1 - σ[T])); g2[T]=(1 -...

Why is it that when integrating over all angles, integration is over the solid angle omega composed of theta and phi but the vector angle within flux, phi( r, E, omega), is resolved into the cartesian coordinates by cos(theta)sin(phi), sin(theta)sin(phi) and cos(phi) which is essentially the dot...

Hi, I've been wondering about this a lot and I didn't find a satisfactory answer by myself. My professor said that in order to promote a fission reaction you need to provide a certain amount of energy (like in a chemical reaction you need to overcome the activation energy) and the easiest way...

I've just watched a vid about jets of matter and neutron stars. It was stated in it that a neutron star is a star that's been compressed from say a sun sized star to the size of a city, every thing OK upto now. Then it goes on to say that it has, the neutron star, enormous gravity, this is were...

Hello everyone. I'm currently working on NS mass relations and trying to plot a curve with predicted masses-radii and observations on NS. There are some free data at this website: http://xtreme.as.arizona.edu/NeutronStars/index.php/neutron-star-radii/ . I downloaded the .tar file and tried to...

if we teleport a small amount of millimeter cube of a neutron star outside it, will it remain still as a very dense heavy neutron clump or will it revert back into its components (iron) or will the neutron destabilize and turn into cosmic radiation of neutrons which then turn back into hydrogen?

Homework Statement Calculate the velocity of the fastest neutron in a 96Mo nucleus and, based on this, explain whether or not we are safe to consider such nucleons in a non-relativistic way. Hint: first calculate the Fermi energy. Homework Equations Fermi energy from Fermi gas model...

Please forgive the awkward title. "Supermassive black hole" uses up a lot of the title character limit. Has anyone made a simulation of what would happen if a neutron star impacted a simplified (Schwarzschild) supermassive black hole? I've seen simulations of a neutron star colliding with a...

Homework Statement A certain odd-parity shell-model state can hold up to a maximum of 4 nucleons. What are its values of J and L? What about an odd-parity shell-model state with a maximum of 6 nucleons? Homework Equations Parity = (-1)L J = L+S Total angular momentum, J, is equal to orbital...

When neutron stars collide, heavy elements, such as gold, are created. Are these elements ejected from the system to be found, say, here on earth? Or do they fall back into the newly created black hole?

Proton is made of 2 up, 1 down quarks Neutron is made of 2 down, 1 up quarks The up and down quark have different masses, which account for some of the mass difference. I've also read that hadron masses depend upon the interactions/dynamics inside the particle, not just the quarks contained...