Neutron Definition and 770 Threads

Hey all, Does anyone happen to know the value of ν∑f for natural uranium? Here ν is the average number of neutron released from fission and ∑f is the macroscopic fission cross section of uranium. Kirk

I'm just reading over some experimental notes for neutron activation analysis and I see the mention of a spacer being placed between the irradiated sample and the detector face. What does a spacer actually do? I did a quick google but couldn't really find anything.

When a target is irradiated with neutrons there a number of different nuclear reactions that can occur. In neutron capture, which neutron energy regime is most dominant? I can't seem to find any specific literature about neutron capture and neutron energy, but most of the general stuff I've read...

I was just wondering if there is anything to suggest that black holes are anything but giant neutron stars cloaked in an event horizon created by their own gravity. I mean if a neutron star is just on the cusp of having enough mass to be a black hole, and then gains that mass, what's to say it...

Title says it all. Made a few google searches and couldn't find any information. Is there a reason why it is so large, or is it just a coincidence of nature?

Do neutron stars have a minimum volume? Anything "in the way" of perhaps baseball sized neutron star? Or would something like that be an impossibility? How neat to have one in a laboratory...or not lol

Homework Statement What is the kinetic energy given to the proton in the decay of a neutron when: a) The electron has negligibly small kinetic energy b) The neutrino has negligibly small kinetic energy Homework Equations Q = (mn - mp - me - mv ) c2 = .782MeV Where T is kinetic energy, and...

Hello everyone, Today I'm asking you for help to put together these two equations of state for high densities BPS-BBP with a eos of a pure neutron gas or a non interacting n + p + e gas. I have already the data of BPS-BBP equation of state, with includes neutron drip and let a open space to...

Neutron stars are neutral by definition. How can they have magnetospheres which are polar by definition?

why neutron get so little energy in fission reaction as compare to fission fragments? according to formula Em=Ef(M)/(m+M) m=mass of small fragment M= mass of relatively big fragment Ef=fission energy by the same logic neutron should get highest share due to their lower mass. i am missing...

Homework Statement when fission occurs why neutron get less energy as compare to the daughter nuclei? i need both physical and mathematical explanation. Homework EquationsThe Attempt at a Solution i think it is due to the small mass of neutron. but i am not sure as it is not satisfactory. a...

Wikipedia(https://en.m.wikipedia.org/wiki/Photon_sphere): 'This equation entails that photon spheres can only exist in the space surrounding an extremely compact object (a black hole or possibly a neutron star)' But how can a neutron star? I have a doubt because 1. When а mass of а star...

I am wondering if anyone has determined by experiment or calculation at what rate or even better what frequency the quarks move around at inside a neutron and proton? Do neutrons or protons vibrate at a specific frequency.

Homework Statement the question details are given in the attachment Homework Equations momentum = √2mE where m is mass of neutron and E is its kinetic energy The Attempt at a Solution initially i accounted for the energy change during the path followed by the neutron but later i got...

Hi, My textbook has a multiple choice question about which stellar object has the highest surface temperature and the answer was a white dwarf. However, one of the options was a neutron star. Neutron stars are much denser and have been crushed by gravity even more plus they are rotating at...

Hi, I have been trying to get some physics behind the cause of the degeneracy pressure but have some confusion with the stuff I have found. Apparently the cause of degeneracy pressure can be explained through the uncertainty principle. If you trap electrons in a smaller and smaller space the...

Although it is definitely not simple, there are many reasons to consider that baryon number can be violated, for example: - while baryogenesis there was created more matter than antimatter, - hypothetical Hawking radiation can finally turn any matter (mainly baryons) into massless radiation...

Hello everybody, I am performing some experiments with a neutron generator. Specifically D-D reactions. I am trying to replicate the measurements with MCNP6, but I do not know how can I simulate the neutron generator with MCNP6 since the neutrons have a angular distribution. For MCNPX there was...

If a neutron star can be seen dense enough in some inertial frames of reference (due to relativistic length contraction) to form a Black-Hole, but not in others, how could the two realities coexist? Thank you in advance.

Hello everyone. I'm looking for an good equation of state for a neutron star, I'm starting with a degenerate neutron gas, but i have nothing to compare my results, I've search on the internet for it but haven't success. May you guys could have any graph of it to help me ? Thanks a lot.

how to convert MNCP F4 tally to neutron flux (n/cm2s). and how to calculate average neutron produced per fission from given nuclear fuel mixture (eg. mixture of 80.8% enriched U-235 and U-238 as fuel material).

I'm told that the MnO crystal resembles in structure that of NaCl (FCC) with lattice constant a, and am first asked to write a general expression for the position vector Rj of the ion j in the unit cell of MnO. I am then asked to find the vector K for MnO in order to use the relation...

Since gravity is stronger the closer you get to center mass, is it possible some neutron stars have a black hole inside?

I know there is theoretical possibility of making mini black holes in particle acclerators, but what about mini neutron stars, or even mini quark stars? I realize the neutron decays in 15 mins if left all alone. What is the minimum number of neutrons needed inside a nuclei for it to be stable...

Hello, I've heard that MCNP outputs delayed neutron fractions (beta) and neutron generation times (Lambda). Any ideas as to where in the output file it writes these? I've coppied and pasted the Godiva reactor code and run it, but I can't seem to find it in there. Best Regards, -TP

Hi guys, I have a question that I can't seem to wrap my head around. This is the question: A power reactor is fueled with slightly enriched uranium. At the end of core life (i.e., when it is about to be batch refueled), 30% of the power comes from the fissioning of the built up Pu-239...

The mass of a neutron is approximately 1.674927471×10−27 kg, but is this always the case? For example if a neutron undergoes negative beta decay (i.e. an electron and an electron anti-neutrino is emitted) and then positive beta decay, will this not mean that the final mass of the neutron is now...

My book says that a free neutron, unlike a free proton is unstable. It decays into proton, electron and a antineutrino, and has half life of about 1000s. I do not understand how a single particle can have something called half life. I am finding difficulty to think of a proton being reduced...

Some observed neutron stars rotate hundreds of times per second. Speeds at the surface of these stars are as much as 15% the speed of light. These huge speeds are generated because angular momentum is conserved when a large rotating pre-super nova star collapses into a neutron star. The...

In PWR, fast neutron produced from fission in fuel has been moderated into thermal neutron by the a series of collisiion with coolant,i.e. H2O. So the multi-group neutron flux in coolant and fuel pin has much diffenrce, e.g. the relative higher fast neutron in fuel pin and relative higher...

The specific information of secondary neutron source in French 1300MWe and N4 PWRs are needed, e.g.the total mass of Sb-Be in core and the thickness of Sb-Be cladding with stainless steel, but unfornately I couldn't find any useful information in google in English. I guess some informatio could...

Homework Statement So my teacher set us half term homework and one of the questions was state the relative size of a proton a neutron and an electron Homework Equations Not sure about equations The Attempt at a Solution Im a bit confused because everyone in my class got Proton: 1 Neutron: 1...

Homework Statement reactor consists of nested spheres (sorry, this is my first time posting): Sphere 1 --> Lead target with radius of R0 (Target-region) Sphere 2 --> Actinide Fuel surrounding lead target; has outer radius of R1 (A-region) Sphere 3 --> Reflector surrounding the fuel with outer...

Hi everyone, I am supposed to derive the neutron flux equation provided for region A of my reactor. Just wondering if anyone can help me out since I stuck on the derivation for [1/r - 1/R2]; S/4πD aspect is very similar to a solving the constant for a point source spherical reactor Here is my...

I was overlooking page 47 of "The Physics of the Manhattan Project" 2.2 Critical Mass: Diffusion Theory, and author Bruce Cameron Reed reported that: Can anyone explain how Bruce Cameron Reed got from (2.18) to (2.19) I tried plugging ## N(r,t) = N(r) N(t) ## into (2.18) to get (2.19), but it...

Particle accelerators use the electromagnetic field to accelerate charged particles. Would it be possible to build a particle accelerator for uncharged particles? Say we are given a narrow beam of neutrons. How could we accelerate them so that the accelerated particles were still in a...

Hi everyone Does anyone help about unit of below MCNP line for neutron? Is it "neutron*barn/cm^2" right ? fm14 (1 108 102) And also what's the unit difference between "fm14 (1 108 -6 -8)" and "fm14 (1 108 -6 )" ? Many thanks

I remember reading that in addition to the ITER, that they're also building a facility to study the intense neutron flux that is expected from the reactor in order to study how to better protect materials from the flux. Anyone remember the name of the facility? I'm having trouble finding it.

Hi, i am looking for some help on MCNP, more precisely mcnpx 2.7 for neutron simulation. I created a model of semi opened detector with a various number of 1 inch He3 (here 16) and i only obtain 6-7% efficiency. the fact is, I've others technicals notes about same "types" of detector, for...

I was wondering if a binary system of neutron stars were to collide what kind of nova or supernova would it be. Is it different if the final mass of the neutron star is sufficient enough for a black hole or if it still a neutron star?

I have heard that in neutron stars, the atoms do not repel nor do they attract. In a sense, could this mean that these atoms nucleuses could touch each other, or could the atoms touch in general?

Now I'm familiar with how nuclear fission works to produce thermal energy and alpha/ beta/gamma radiation, but how do they work in the bomb? When is the high energy neutron fired into the uranium-235, and when does the chain reaction producing the heat begin? Why is it that there's a huge...

Essentially what would it take to create a man-made neutron ballast/balloon (free neutrons under pressure contained in a vessel ) Essentially a pure neutron star on a small scale. In larger scale during a stars collapse protons and electrons essentially are forced to occupy the same space acting...

[This thread was split from https://www.physicsforums.com/threads/a-light-wave-and-a-sound-wave-travelling-together.878450/#post-5518001 as it's an interesting topic in its own right] That's actually an important point, in the core of neutron stars, the speed of sound increases with the...

Hello, For a given excitation energy, why a nucleus "choose" to evaporate preferentially a neutron or a proton? I mean, let us take for example the isotope 208Pb. Its neutron separation energy is 7367.87 keV while its proton separation energy is 8004 keV. If this isotope has an excitation energy...

When neutrons are fired at atoms, if at higher speeds they will behave as waves, wander through and scatter, (which can produce something similar to x-ray diffraction images), but if slowed to the right "thermal energy" speed, they will be captured by (say) U-235, making the U atom unstable...

I have been researching in the Forum, but I did not see anything conclusive about this: sorry if that was posted anywhere else here, I am new here :smile:. The energy loss of a neutron after an elastic scattering is a pretty straightforward calculation that can be done by hand. However, I am...

So, I'd like to calculate the dose rate to an object, say 1g of quartz (SiO2) placed into a research reactor neutron flux. The average kinetic energy of research reactor neutrons is 2 MeV but individual neutron energies vary dramatically. Say the thermal neutron flux is 1E13 n/cm2/sec and the...

i am a physicist now i am doing Ms in nuclear engineering ... i need to understand basic concepts ... neutron transport equation ? what is the transport phenomenon actually ? and pressure drop calculations in core ... please help thanks in advance

Homework Statement Homework Equations rotational kinetic energy = 0.5 I ⋅ M ⋅ ω², where I is the moment of intertia, M the mass and ω the angular speed The Attempt at a Solution T = period of revolution K = kinetic energy associated with rotational moviment Since T increases with time...