Neutron Definition and 770 Threads

Hey, I am yet to study particle physics or QM but in a few forums i have read that there is a particle called a tachyon which travels faster than the speed of light. I told my mate this and he asked "if you collide a tachyon with say a neutron which is traveling lower than the speed of light...

Homework Statement Hey all, I need a help to determine the Mass-Radius relationship for a neutron star. I've done it for a white dwarf, but for a neutron star I need to know the Neutron degeneracy pressure expression, can anyone please help me to solve it? I am thinking that if I have...

Hey all, I need a help to determine the Mass-Radius relationship for a neutron star. I've done it for a white dwarf, but for a neutron star I need to know the Neutron degeneracy pressure expression, can anyone please help me to solve it? I am thinking that if I have the n.deg.pressure...

Anybody have good values and a source for thermal neutron capture cross section for Ba-133, both ground and excited states? CRC Handbook gives 4 barns, but wanted to verify it. Thanks.

Does anybody in PF-land use neutron moisture meters - the ones with Am-241/Be sources that probe into holes in the ground? If so, do you have a regime for regular wipe testing and leak testing? I am interested to find out if there are any cases of a wipe test result that showed contamination...

I have not found a discussion open on this, and I would like to know if anybody has an opinion. My questions are triggered by the 0802.2563 arXiv paper (Meson Clouds and Nucleon Electromagnetic Form Factors by G. Miller). It has long been believed that the neutron electric charge density is...

Is there a simple-model equation for the radial density of a neutron star, from core to shell? I assume there have been models of fermionic gases, anyone have something onhand Is it a specific distribution? Linear? 1/r^2? I know its just a balancing of gravitational potential with strong...

I could not find much info on neutron degenerate matter. Only in reference to neutron stars. http://en.wikipedia.org/wiki/Degenerate_matter neutron degenerate matter Has anyone looked at the possible properties of a neuton liquid or solid to determine if it could act as dark matter? jal

Not sure where to put this post, care more about what's happening on atomic scaI le so i put it here. I am currently taking Heat transfer for engineers and we were discussing the mechanicals for heat transfer, conduction, convection, raditation. In class my professor said that conduction is...

The words neutron degeneracy pressure and electron degeneracy pressure are thrown around a lot when talk of white dwarfs, neutron stars, and black holes comes up. Despite this, I can't find a quantitative description of these critical pressures ANYWHERE. It is almost always described in terms of...

The Chandrasekhar limit (~1.4 Msolar) is an upper limit to the mass a white dwarf star. So this means we can not have a white dwarf star in nature that weighs more than this. But is it true that we can have a neutron star that weighs less than 1.4 Msolar? If so, this makes no sense to me...

Neutron Reaction? Now, I am doing a research about neutron reaction with many level of energy. With intermediate and high energy, I use optical model to calculate the total cross section of the reaction. But in the low energy, I can not do like that because I do not know about the parameters of...

Suppose the neutron decay time n was 89 sec. AND the difference in rest mass between neutron to proton, Qn, was 0.129 MeV. What would the maximum Helium fraction, Yp, be?

Homework Statement "During most of its lifetime, a star maintains an equilibrium size in which the inward force of gravity on each atom is balanced by an outward pressure force due to the heat of the nuclear reactions in the core. But after all the hydrogen "fuel" is consumed by nuclear...

Why is the nn-pair unbound? I don't seem to find the answer in any of my textbooks =/

Homework Statement Neutron stars, such as the one at the center of the Crab Nebula, have about the same mass as our sun but a much smaller diameter. If you weigh 675 N on the earth, what would be your weight on the surface of a neutron star that has the same mass as our sun and a diameter...

I'm writing a paper on Thorium utilization in nuclear reactors. In this connection I'm looking for figures which describe the neutron capture and neutron fission cross sections over a wide energy range (not only thermal). There are probably some online resources unbeknown to me, any hints?

I've looked around and not found any good sources on the gamma energies from fast neutron activation. I need to find the characteristic gamma rays for an MCNP project and currently, I'm relying on energies I get from running some simple cases I set up for the element of interest. Does anyone...

What happens to the neutron? :smile:

It never occurred to me until now why instead of using two charged protons to fuse together, rather fuse neutrons to a hydrogen nucleus. Yes, it seems like cheating the system and therefore that's why I've not heard about this before, but what is the exact mechanism that prevents this from...

It's part of my homework to find an analytical solution to a slab reactor with a reflector. The setup of the core is two slabs of equal thickness (-a to 0 and another 0 to +a) but different values for the diffusion coefficent, macroscopic absorption cross sections, and \nu \Sigma_f. There is a...

At a macroscopic level it appears that when two objects collide, they physically interact and the atoms touch. However the charges of the electrons actually repel one another and they don't physically touch. Correct? A neutron however has no charge so what happens when a neutron collides with...

Hey! I have a question, whose answer I was unable to get after reading some articles regarding neutron start. I've understood that neutron stars lose their rotational energy and emit fragments of it to earth, thus slowing down through the years. I know that this process takes billions of...

I see that in some books, Proton and Neutron charge differ a bit. Why is it? :confused: I thought them to be same. But... And I am new to this forum... Let's hope we will have a great time together studying science...

Is it possible for a beam of slow neutrons, to be deflected by a strong magnetic field? I have found something for a beta asymmetry in Wu experiments, but haven't understood much. Is it a particle physics subject?

Does anyone know what the necessary conditions are for a nucleus to undergo fission with a thermal neutron? I have found something for the chain reactions, but not very helpful. I want to find out the conditions for ONE nucleus to undergo fission with a thermal neutron.

Homework Statement 1)Neutron emission is not a possible mode of decay for K(40,19).Why? Homework Equations The Attempt at a Solution I think it is because the neutron to proton ratio for potassium(40,19) is almost unity(more precisely N/P=1.1). So, neutron emission is not a mode...

Homework Statement 1) In a sequential process, U(235,92) plus a neutron forms the compound nucleus [U(236,92)]* which then fissions; the fissions then produces decays. If the initial fission fragments are Ba(143,56) and Kr(90,36), illustrate a process leading to the final stable nuclei...

Consider a reactor being held sub-critical, Keff < 1, by control rods. The reactor has heavy water reflector and has been operatored for some time prior to the current state (we got Photo Neutrons). Keff is then bought to 1. It seems to me, for Keff = 1 the neutron population should be...

can a neutron decay into a proton? i certainly didnt think so, but i am reading hawking's new little book "breifer history of time", and he states that in there while talking about the early universe. thanks.

Hi guys, I'm not to great at physics and all but I want to learn more. I hope you guys can help me in that aspect.First of all, how do neutron stars form? I was told their electrons shrink into their nucleuses and therefore the whole star shrinks, but what causes the atoms to behave like that?

A (free) neutron has a lifetime of some 10 minutes or so, how come it is stable in a nucleus?

I have a question about current experimental findings on the status of the neutron N while contained within nuclear radius of a stable atom, say Helium-4. It is well known that the N will undergo beta(-) decay when it is free from a nucleus (takes ~ 14 minutes). But... My question...

hiii guys, what's the binding energy of a neutron and how do you arrive at the answer? durrrrrrhhhhhhhhhh :confused:

I read a sentence in my book saying, The fast neutrons released through the first nuclear fission are passed into the moderator, thus producing (becoming) thermal neutrons. What is a Thermal neutron? What is the difference between Thermal and a Fast Neutron?

Hello, I can't find :confused: where do we get the starting neutron(s) for the chain reaction in the reactor. I'm aware that then the splitted atom emits enough(in fact even too much?) neutrons to selfsustain the reaction, which are then slowed down to be able to split uranium and so on...

I am plotting the in-hour equation. For the delayed neutron fraction, I was thinking of using a weighted dnf for the particular U fuel enrichment of interest, ie combination of U235 & U238 dnfs, as I cannot look one up for this particular enrichment. Any comment on the “validity” or otherwise...

Can anyone hepl me with this?I need some web resource,to start learning from scratch.

Hello, Can someone explain to me exactly why a bound state of two identical nucleons is not possible? I have a feeling its something to do with antisymmetric wavefunction, but haven't found a satisfactory explanation in any book. Cheers.

Homework Statement Suppose the sun collapses into a neutron star. What will its radius be? The questions also gives some backround explaining that stars fuse hydrogen into helium until they collapse into a neutron star. The protons and electrons fuse into neutrons with the density of nuclear...

The question is: Suppose the sun collapses into a neutron star. What will its radius be? The question gave a brief backround explaining that stars are powered by nuclear reactions that fuse hydrogen and helium. When the hydrogen is used up the star collapses into a neutron star. The force of...

A neutron star has a mass five times that of Earth and a 10 KM radius. Find the distance from this star's surface a satellite must be at to stay in a circular orbit if the satellite is moving at 50000 km/min. First, I changed the 10 KM to meters and found the mass of this neutron star...

Neutron stars represent the final stage of life for some massive stars. Typically, they have radii of 10 km. Determine the magnitude of the centripetal acceleration for a piece of neutron star matter on the star surface at the equator (so the matter moves in a circle of radius 10km). Assume...

I was wondering if some of you could describe a couple of the applications of a neutron generator and or suggest some further reading on the types of such?

Does anyone know of a good reference regarding solving the Tolman-Oppenheimer-Volkov equations for neutron stars? Most things I find are either too elementary and others skip multiple steps. I think the EoS to use should be that of a Fermi gas model, but I am not sure.

I was intrigued by this paper, and apparent implications for Smolin's cosmic natural selection [CNS] conjecture. http://arxiv.org/abs/astro-ph/0609644 Observational constraints on quarks in neutron stars Authors: Pan Nana, Zheng Xiaoping Comments: 16 pages,6 figures We estimate the...

Does anyone know if there are descriptions of the neutron and proton configurations in atoms and why certain configurations are more stable than others. For example the average atomic mass of oxygen and flourine are the whole numbers 16 and 19 while most other elements have more variation...

hi, in neutron scattering, if the lowest kinetic energy of a neutron is increased by a factor of 2, how do you work out the number of peaks produced? I have worked out the lowest kinetic energy for a beta-brass CuZn to be 2.37meV using [tex]E=\frac{\hbar^{2}k^{2}}{2m}[\tex] where...

We were having a little chat in my physics lesson about neutron stars for our A level course, and nobody really understood why neutron stars have a magnetic field if they are consist of neutrons, which are obviously neutral charge. We thought that you needed charged particles to create a...

The situation involves a neutron in a constant gravitational field (g=9.8). I need to find the energies of photons that transition to the excited state. I solved the Schrodinger equation by doing a variable transformation using Airy functions. To fully solve, however, I need to find the roots...