Neutron Definition and 746 Threads

Dear PF Forum, I have a question to ask. Supernovae produce neutron star (or Black Hole). This is what I summarize from wikipedia. 1. Is P + e = N? Is it that simple? Judging by its mass, altough slightly off. 2. Is Up Quark + e = Down Quark? Thanks for any answer

Could anyone tell me or direct me to a source with an answer or way to calculate the neutron aborbtion/interaction length of lithium-6 deutride? I would have expected this answer to be readily available from the government experiments leading up to castle bravo, but I cannot seem to find it. Any...

Homework Statement Write the equations for neutron and proton fusion to form deuterium and for deuterium photodissociation. Homework EquationsThe Attempt at a Solution There is plenty on proton-proton fusion to form deuterium, but not much on proton-neutron. Is it simply p + n -> D ? Is...

As far as I understand, ##I_{3}##, the component of isospin in a certain direction is additive, but ##I## is to be treated as a vector sum, is this correct? So, ##I_{3}=1/2## for ##u## quark, ##I_{3}=-1/2 ## for ##d## quark. Adding ##I_{3}## then for a proton we find ##I_{3}=1/2## and for a...

Dear PF forum. Folks, what I have here may be an unimportant question. Still I'm curious to know the answer. When iron fusion happens in a massive star, it will undergo supernova. What I want to know is... 1. There are some binary (or perhaps ternary) neutron star systems. Neturon star is...

Homework Statement A neutron in the nucleus of an atom can move in a range which is about five femtometers long. Use Heisenberg's uncertainty principle to calculate what velocities one can expect to measure. Homework Equations \sigma_p \sigma_x \geq \frac{\hbar}{2} p = \hbar k Probably others...

I was reading about control rods in a nuclear reactor. The carbon rods slow down the neutrons so they can interact better and induce fission. Is the reason that they don't interact when raveling fast is this because the have a smaller de broglie wavelength?

which stage of the sun consists neutron star/stars

Hello everyone, Can a hadron be in an excited stage? If yes, can neutrons -the element- neutronium have a nuclear isomer in a metastable stage, making it have a longer half life?

I try to find answer to quite basic question. Let's imagine neutron star and object with mass of 1 kg located far from the neutron star. Total energy of the object is ##E = U_g + mc^2##, for case when its velocity is zero and and ##U_g## is potential energy of gravitation. The neutron star have...

I saw a thread that asked the same basic question as I'm asking, but the explanation was beyond my current knowledge. Please consider answering my question as if you were being interviewed for a Discovery Channel special and had to make it comprehensible for a general audience. Thanks! For me...

Hi All, I have a basic question. I am still new to nuclear engineering so this maybe a stupid question, but what is the typical energy efficiency of a neutron source? (I.E. power of neutrons emitted/power input for neutron generation) I recognize that the efficiency can depend on the neutron...

The arrows in a Feynman diagram represent electric current. right? If this is the case then why do neutrons and neutrinos have arrows. How do they have an electric current?

When matter is crushed in a neutron star are the atoms of molecules closer and the electrons are the same distance from the nucleus, or is the electron cloud closer to the nucleus? If the latter, how is this possible if the orbits have to have fixed orbitals due to the standing waves of the...

Hello everyone... I've been trying to make a list about moderator materials used in nuclear reactors. So far I've found some but still wondering if there exists more than I learned and also wondering if they are correct. Please see the list below and feel free to correct my mistakes or to add...

Homework Statement https://dl.dropboxusercontent.com/u/62834965/neutron_interferometer.png Consider a neutron interferometer (NI), such as the Mach-Zehnder interferometer in the figure. We send in a beam of neutrons. We assume that the flux of neutrons is so low (neutrons can be very slow)...

Neutron stars are supposed to have an upper limit in mass, beyond which they collapse into perhaps a further type of degenerate matter or a singularity. There doesn't seem to be precisely defined upper limit, but the limit is estimated to be 1.5-3 solar masses. However, a hypothetical neutron...

The fastest moving pulsars are theoretically spinning neutron stars. They probably got their velocity from a kick from a supernova like Project Orion. http://chandra.harvard.edu/photo/2012/igrj11014/ http://chandra.harvard.edu/photo/2003/b1957/closer_look.html As I understand it, neutron stars...

Show by direct calculation that Eqs. (4-134) and (4-137) in the textbook by Duderstadt and Hamilton hold, i.e.:(a) ∫ dΩΩiΩj= 4π/3 δij; i,j = x,y,z; 4π(b) ∫ dΩΩxΩyΩz = 0, if l, m, or n is odd. 4π The integrals are over 4π. This is part of the derivation of the diffusion equation...

I was reading that the ITER will take advantage of the energetic neutron flux by using them and lithium 6 to breed tritium for more fuel, and to use multiple heat exchangers to grab their energy. And just to make sure that I'm reading it right, the main problem with the neutrons will be their...

I need urgent help! we have a beam made of some neutrons and some photons. I thought about the beryllium polycrystaline but I'm not really sure it could work. The beam has an energy of 2 MeV moreless. Sorry for my spoken english.

I've gotten a bit confused about the creation of the neutron star/pulsar, so I was hoping someone could point me in the right direction :) As fusion stops, when reaching the iron phase, the outer layers (hydrogen, helium, carbon... etc.) gets pulled in-wards do to gravity. This creates a bounce...

The reaction p→n+e++νe is common inside nucleus. But it not considered when we talk about free particle and reason is simply given mass of products being larger than reactants. Now my question is if there is a high energy proton having total energy in order of 2 GeV or let it to be 100 GeV (To...

I had a question and I found a thread on PF with a nearly identical question ---Slowly add mass to a neutron star till it collapses. I learned some very interesting physics from that thread, namely the Tolman–Oppenheimer–Volkoff limit, and the significance of "9/8 of its Schwarzschild radius"...

hello I solve neutron diff eq for plane source in the vicinity of slab of water but if i substitute source term with 1 the flux in some places is greater than one! how it possible?! i am sure about my calculation so someone say me how it possible?

when we calculate the neutron flux in finite medium using sn method for steady state neutron transport equation, it gives us some numbers up to 1. I am sure its not the real flux, can someone explain how we can calculte the real flux using sn method.

Hi, I was reading about free neutron beta decay the other day and it came to me the idea of neutron stars. As I understand, neutron stars are held together by gravity instead of strong force interaction (which I think is the mechanism that gives stability to neutron in common nuclei). So one...

A recent issue of Aviation Week described a novel design for a fusion reactor from the Lockheed Skunk Works. It was smaller, simpler and lighter than the extant systems now being built and they're optimistic about it's test run in five years. I wrote a letter to the editor touting this departure...

Hi guys! Im i have to write a paper on neutron an x-ray inelastic scattering. So far I have red a bit of information on this subject. As far as i can tell the main use x-ray an neutron inelastic scattering is determining the phonon energy,wave vector,intensity and so on. The thing is that...

My first question is: is easier to reach D-D fusion than Be(alpha, neutron)C reaction??In Am-Be neutron sources or similars, the yield of neutrons is too low compared with neutron tube sources, then, these last are too much expensive. So, it could be a good idea to modify the design of...

Homework Statement A neutron strikes a Plutonium-239 (239Pu) nucleus and creates Barium-142 (142Ba). What other element is created? Homework EquationsThe Attempt at a Solution I actually have no idea...could someone just start me off? Thanks!

Homework Statement Exercise 2.6 (page 28) Consider completely ionized matter consisting of hydrogen, helium, and heavier atomic species i>2. Let X and Y denote the fractions by mass of hydrogen and helium, respectively. Show that \mu_e=\frac{2}{1+X}. Approximate m_i=A_i m_u for all i, and...

I've seen explanations that when a neutrino with a W+ Boson comes near a neutron, it affects one of the bottom quarks and changes it to a up quark which effectively turns the neutron into a proton. The neutrino then turns into an electron. Source: (2:20 onwards) I've seen other explanations...

DISCLAIMER: This thread is a repost of another thread in the Nuclear/Particle Physics forum since I cannot delete that thread but this forum is more appropriate since it is more of a question in Nuclear Engineering than in Nuclear Physical theory. So I have been reading about the operational...

Why and how does a neutron knock electrons off of atoms? Is it because a neutron is not exactly neutral? Is a neutron composed of smaller charged particles which interact with the electrons when it gets close?

Alpha particle emits when no. of neutrons in an atom are much more... My ques. Is that the no. Of protons and neutrons emitted are same so the substance formed after the reaction should still have much more neutrons than protons.. Infact mathematically the ratio increases.

Hi, I am currently working on a Sci/Fi short story where a spaceship leaving a planet will perform a gravitational assist sling through a binary neutron star system. The problem is that I have difficulty finding information about how close a planet could be to a binary neutron star system? I...

I would like to ask if any of you can comment on the thermal neutron activation of lithium in order to produce energy as a cold fusion-like process?

This relates to a feat in a classic Thor comic. Thor is blasted by a Graviton Bomb and "is instantly subject to a gravimetric attraction akin to that of a neutron star.". He is then "pulled irresistibly down by the incalculable increase in local gravity and is quickly buried from view by an ever...

How would you approximately describe matter in the core of underlying neutron star? I am asking for really fundamental properties. No strange matter, consider just n,e,p. A ratio, can we describe particles as free? Gas x fluid x superfluid? etc.

I have been told, that neutron radiation, rather than electron or proton radiation, is used to produce defects in solids. And the reason is that electron has a small mass comparing to the nucleus of an exerted atom, thus can not really displace it, and concerning protons, that most of their...

Is this established or is it dependent on the size of the black hole? http://www.space.com/22180-neutron-stars.html Neutron stars pack their mass inside a 20-kilometer (12.4 miles) diameter. They are so dense that a single teaspoon would weigh a billion tons — assuming you somehow managed to...

1. The problem statement & given/known data A neutron star is a collection of neutrons bound together by their mutual gravitation. The density of such a star is comparable to that of an atomic nucleus (10^17 kg/m^3). a) Assuming the neutron star to be spherical in shape and of uniform mass...

I am looking at the average lethargy gain of a neutron when colliding with a moderator, which is often referred to with the greek letter "xi" (see for example, Duderstadt and Hamilton page 324). There is a general equation for calculating ##\xi##, ##\xi = 1 + \frac{\alpha}{1-\alpha} \ln...

Homework Statement Good morning or afternoon. My quantum physics teacher has given me a task: Given a neutron beam of mass 1.27*10^-27 kg and known energy E impacts on a lineal chain of atoms with a known distance between two of them l. A detector intercepts the wave diffracted an angle o. I...

As the title of the thread suggests, I'm interested in estimating the velocity distribution of neutrons in neutron star cores. Putting T ~ 10^12K gives v ~ 15%c or more under Boltzmann statistics. Could someone provide more information or a second opinion on this estimate? Thanks.

1. The problem statement, all variables and given/kown data Assuming that the nuclear radius R=γ0 *A(1/3) where γ0 =1.2×10(-15) and A is the mass number, Calculate the neutron and Proton densities in a nucleus N=Z. Homework Equations A=N+Z.=2Z in this case. Mass of proton =Z*mp Mass of...

What would happen to a neutron star (on the cusp of becoming a black hole) if it were sped up to near the speed of light? Or more easily done, if I sped up to near the speed of light. Would the additional mass from the near light speed cause the neutron star to collapse in on itself and form a...

Hi, PF: I'm currently about to graduate from my Ph. D. program in Physics and I want to focus my research in theoretical physics. I feel very excited by topics such as Astrophysics and GR, but also low temperature physics, such as superconductivity, bose-einstein condensation, superfluidity...

How would one calculate the velocity of a 1MeV neutron?? I tried the following the attached formula for V/C but E is less than the rest mass which yields the square root of a negative number. Not sure what to do for this