Neutron Definition and 746 Threads

Most accepted theories make sense, but the energies involved in the beta decay of a neutron into a proton confuses me. How can a down quark change into an up quark by emiting an electron and an anti electron neutrino via a w boson, the figures don't add up! Using the figures of mass it goes...

Homework Statement The Gravitational binding energy of an object consisting of loose material, held together by gravity alone, is the amount of energy required to pull all of the material apart, to infinity. the gravitational binding energy Ug is roughly given by GM^2/R. how fast do you have...

Homework Statement Certain neutron stars (extremely dense stars) are believed to be rotating at about 6 rev/s. If such a star has a radius of 15 km, what must be its minimum mass so that material on its surface remains in place during the rapid rotation? G=6.67*10-11m3 kg-1 s-2 Homework...

why does fission chamber start to work from neutron fluxes more than source range in spite of being a kind of ionization chamber that is sensitive to gamma rays?

I've never really understood how a bound neutron can have a kinetic energy and potential energy associated with it. Further, I'm not sure that I quite understand what the potential energy of a free neutron means. I know that these questions might be rather elementary, but when I stopped to think...

Just over half-way down this page:- http://www.embedded.com/columns/technicalinsights/220301380?cid=RSSfeed_embedded_news it says:- "These sunspot counts show variation on a cycle of roughly 11 years. By overlaying Oulu neutron measurements with sunspot count data since 1964, we see that...

Say we slowly add mass to a neutron star till it collapses to a black hole. Just before it does has time in the neutron star almost come to a stop? Is the passage of time different for different locations in the neutron star just before it collapses? Would the strings of string theory come to a...

Gravity acceleration value depend on planet and stars mass. On the earth, the well known average value is 9.81 ms-2. On the sun, I read 1200 ms-2; is it true ? does exist a curve giving values depending on mass ?

Do Neutrons and anti-Neutrons annihilate? I can't imagine any reason why they would, I just thought I'd check.

Hi! I hope I've posted this in the right section, but it definitely deals with the nucleus, so here goes. I'm doing a presentation on Boron Neutron Capture Therapy, which, if you don't know, puts boron inside tumor cells, shines a neutron beam onto those cells, which causes the boron inside...

If a neutron star accumulate materials from its companion star ,then it's mass exceeded Tolman–Oppenheimer–Volkoff limit, it will collapse into a black hole! My question is ,in this case ,it will produce "gamma-ray burst"?

Homework Statement A neutron has an elastic collision with a stationary deuteron. Mass of neutron is 1 amu, mass of deuteron is 2 amu. the neutron is deflected through 90 degree angle. Prove that the neutron loses 2/3 of it's initial kinetic energy to the deuteron. Homework Equations...

How many neutrino emission mechanism, that causes the cooling of star, are there in neutron star? And How, what equation, to calculate the emissivity of each mechanism? thankfully, First

Hi, in a lecture I was told that the cooling of neutron stars cannot happen via the 'direct' Urca process (beta decay and inverse beta decay), because the created particles cannot go into occupied states (Pauli exclusion). The 'modified' Urca process was introduced, with an additional neutron...

I was wondering about the light emitted by one of these neutron stars. To my limited knowledge, neutron stars are among the discrete objects in the observable universe with the strongest gravitational and EM fields [black holes beat the living crap out of neutron stars, but that's besides the...

I am looking for thermal neutron scattering cross sections (0.025eV) for individual isotopes, having found non isotopic data for most elements in a textbook. The most comprehensive cross section database appears to be http://www.nndc.bnl.gov/sigma/index.jsp?as=238&lib=endfb7.0&nsub=10"...

Homework Statement Calculate the binding energy of a neutron in 14N Homework Equations E=mc^2 delta m * 1u + E The Attempt at a Solution The mass of Nitrogen (from periodic table): 14.007amu Calculated mass of N: 7 protons (7 * 1.007277amu) + 7 neutrons (7* 1.008665amu) +...

Homework Statement \ (From a past exam paper) Na-24 can be produced by irradiation of 27-Al with energetic neutrons. It decays by beta emission. An aluminium sample of mass m=0.2g was irradiated by energetic neutrons for a period of 1 hour. Two hours after the end of irradiation the total...

I was reading a blog where someone stated that the decay of a free neutron is characterized by a 'mean lifetime' but not by a half-life. They went on to indicate that the decay time is not random (in the sense that leads to a true half life) but rather most decay at the mean lifetime (said to...

Neutron Stars and Special Relativity and General Relativity Here is a question which I can't quite wrap my head around: Suppose we have a Neutron Star that is borderline on the Chandrasekhar limit in its rest frame. In another frame, the Neutron star is moving. As a result, its density...

Hey all, My year 13 physics students stumped me with this one: Why don't Neutron-Neutron (or P-P for that matter) states exist? Thanks in anticipation... Mr T

if you took plain neutrons, and put them in a bottle would a bottle full of neutrons weigh less than a bottle of bear protons with no electrons arround?

hi folks, last problem I can't get done here. I usually have a good idea of where to start, what to use. but I'm a bit flummoxed. Homework Statement A neutron, of mass m = 1.67 10-27 kg, is localized inside a carbon nucleus, of radius 7.0 fm (1 fm 10-15 m). Use the uncertainty relations...

1. Homework Statement [/b] A high energy beam of neutrons of intensity 10^6 s^-1 transverses a target of 238 U of thin foil whose density per unit area is 10^-1 kg m^-2. If the elastic and in elastic cross-sections are 1.4 and 2.0 b, respectively, calculate(a) the attenuation of the beam(b) the...

Homework Statement A high energy beam of neutrons of intensity 10^6 s^-1 transverses a target of 238 U of thin foil whose density per unit area is 10^-1 kg m^-2. If the elastic and in elastic cross-sections are 1.4 and 2.0 b, respectively, calculate(a) the attenuation of the beam(b) the rate of...

hi again folks. this week's set of problems is getting my goat. here's another I can't seem to figure out. Homework Statement In a neutron two-slit diffraction experiment, the slits are 65 µm apart. If the third diffraction maximum is detected at an angle of 2 multiplied by 10-7 rad, what...

I meant to title it "Neutrons packed together" Since neutrons can be packed together in a neutron star, would it be possible to take say five neutrons and pack them together and make a neutroium nucleus. And if not, how come?

If a person could orbit close to a neutron star what color would it appear to be? I have always imgained them to be blue, but this might be totally wrong. :rolleyes:

Since neutrons have no electric charge, how is it that a neutron star is able to produce a magnetic field? :confused:

Hi everybody When fast neutrons hit isolated protons (eg. hydrogen cores in paraffin) the neutrons kinetic energy is transferred to the proton (as they have aproximatly the same mass), which is detectable by a geiger counter, while the neutron is stoped. Thats how far I got after several...

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 650 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...

Does anyone know if an average Neutron star with a diameter of 10 miles, was headed towards Earth.. would our Nuclear weapons be able to physically destroy it? Assuming our technology can provide a direct hit, and do it in time. If so, then how many Megatons would the Nuke need to be, and how...

Homework Statement What is the rest mass energy of one mole of neutrons? Hint one mole is 6.02 x 10[SIZE="1"]23 particles (avocado's number), and the neutron has mass m=1.675 x 10 [SIZE="1"]-27 kg. Homework Equations The Attempt at a Solution I wasn't sure of the relationship...

What is the minimal mass of a neutron star, if the semi empirical mass formula is used?

I have a decent understanding of neutron-induced reactions in heavy nuclei (fission, capture), but less so when light nuclei are involved. I do know of Li6 + n --> He4 + T and the Li7 equivalent. Those reactions are more like nucleus splitting (fission). My question is: do neutron capture...

Hi there, I'm a lay person and would appreciate if anyone could point me in the direction of a good theoretical explanation of the neutron. All I can remember from high school physics is an explanation that went something like:- "Uh, well it doesn't actually do anything, it's just there do make...

Wikipedia said U-238 is better with capturing fast neutrons than slow neutrons. shouldn't it be the other way round? I thought U-238 is not fissile but is fissionble by neutrons with high enough K.E, and doens't fast neutrons have higher K.E.??

well, that's the question. They both have the same queark structure. (udd). is it only their different bound states the differentiates them?? thus giving both different masses?

As I understand it, it can be calculated that 1 minute after the big bang, when protons and neutrons freeze out and are no longer being created, that for every neutron that exists there are 7 protons. Does anyone know what equation is used to calculate this and if it is not a equation that is...

I need help with this problem where we are suppose to determine the fraction of kinetic energy lost by a neutron m=1.01u when it collides head-on and elastically with a target particle at rest which is. examples used.. Hydrogen = 1.01u heavy hydrogen = 2.01u How would you do this? Do...

Here's one for everyone to ponder.. Firstly, this question has always bugged me since I was born. It's not impossible to imagine an Alien civilization 1.5 billion years more advanced than us, using the method of 'Hurling Neutron Stars at 99% the speed of light, to destroy planets and their...

I was told that if there is a wavefunction containing a proton and a neutron that it must be anti-symmetric under exchange of a proton and a neutron. I am having trouble understanding this. The short handwavy explanation is that they are indistinguishable via the color force. What bothers...

Well I was talking to my physics teacher because were currently studying nuclear physics. And he likes tellign stories to make his examples more straight foreward. And I asked the question what types of radiations are in nucleaar bombs. Gama, Beta or alpha. He answered me with those three types...

how plausible is it to image a single molecule using low energy neutrons? I was thinking it might be possible to build something similar to an interference microscope in order to accomplish this however I'm not entirely sure. I was thinking of doing a little research project on the mechanics...

In Modern Quantum Mechanics, Sakurai say that at quantum level the gravity is no more geometrical because the schrodinger equation depend on the fraction \frac{m}{\hbar}. Can someone explain better this claim or link me some detailed paper on this argument?

I want to know if a photon can interact with a neutron? I understand that a photon will mediate the electromagnetic force between electrically charged particles (such as electron and proton). This is even manifested in the photoelectric effect. So, I presume when we "see" matter through...

Since a neutron has no charge and an electron is not involved in the strong nuclear force, does this mean that an electron has no interaction between a neutron? As in a very dense neutron star, would we expect that electrons could easily pass right though without being absorbed/deflected in any way?

Here is a beta decay related question: Masses are from Particle Data Group (http://pdg.lbl.gov/2008/listings/contents_listings.html) Neutron has udd quarks. Mass is approximately 2.5, 5, 5 MeV. Total 12.5 MeV Products are: 1. Proton. uud quarks. Mass approx 2.5, 2.5, 5 MeV 2. Electron...

Homework Statement which of the following has closed neutron shells? (the number in front should be a superscript) 36S, 50V, 50Ca, and there are more but i just want to understand why. Homework Equations The Attempt at a Solution i know the answers, i just don't know how to get...

Using electron-neutron scattering I'm trying to find out how the three quarks (udd) behave inside the neutron. S.Kopeky (Phys. Rev. 1995) found that for small Q2 the equation for the neutrons rms-radius goes towards: -6 \hbar \frac{dG_E ^n (Q^2)}{dQ^2} \right|_{Q^2=0} = -0.113 \pm 0.005...