Neutron Definition and 746 Threads

I have a question about the neutron transport equation, my question is more about mathematics, from the book Duderstadt Hamilton I tried to make the calculations, it should be quite simple but still I don't understand where the 2\pi terms went... the integral over Omega in spherical...

Hello All, Firstly, I'd like to apologize if any of this comes across as wrong or off-putting, as I am a completely new user. However, this question has been troubling me for months. I'm trying to work out an experiment involving the reaction where Li-7 absorbs an incoming neutron, transforms...

As a rule, starting with He, the heavy isotopes of all elements are delayed neutron emitters: He-4 stable He-5 unbound He-6 β- only 807 ms He-7 unbound He-8 β-n 16% of 120 ms then: Li-7 stable Li-8 β- only 839 ms Li-9 β-n2α 50% of 178 ms etc... till Tl-205 stable Tl-206 (RaE) β- only 252 s...

I recently saw a short video describing some characteristics of neutron star, 4U 1820-30, in the Sagittarius constellation, i.e., in that direction. For some reason, it made the news recently, e.g., NICER X-ray Telescope Discovers Fast-Spinning Neutron Star, probably because some results were...

https://www.sciencealert.com/we-finally-know-where-to-look-for-the-universes-most-sought-after-particle

Hello, I want to ask about neutron contamination threshold. Is there a threshold for neutron contamination in tissue used LINAC that is safe and has been regulated by an international organization? thanks for your help.

Considering that when you compress a gas, the gas will heat, then when a neutron star collapses to a black hole, I would expect the neutron matter to be heated to extreme values as the collapse proceeds. I would have thought this would lead to a last gasp pulse of em radiation before gravity...

I know that it is possible to speed up the half-life of plutonium with neutrons. Who can tell me more about this? Thoughts on harnessing this power to decay plutonium so it's unusable in nuclear weapons?

In the following article it is stated: https://skyandtelescope.org/astronomy-news/measuring-neutron-stars-exactly/ "We're seeing the gas whipping around just outside the neutron star's surface," said Edward Cackett (University of Michigan), in a press release. "And since the inner part of the...

I see that the Q value for the reaction 7Li + α -> 10B + neutron is Q=-2789.909 keV, which is a negative value. I knew that Q<0 means that the reaction is not spontaneous. The "Glenn F. Knoll - Radiation detection and Measurement" says: "In particular, the 7Li (α, n) reaction with its highly...

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Hello everyone , in my mcnp coding for finding neutron spectroscopy I used F2 tally across a surface. Is it correct or I should use f4 tally? Morever I need to transform the flux data into neutron fluence. How can I do that. Here I uploaded my code. Though my data from codes is way more...

Hello everyone, currently I am doing a neutron spectroscopy experiments. I am doing it with the MCNP code. I designed my Geometry there, but facing problems in data cards, is there anyone who can help me in this sector?

not asking about neutron stars, where gravity holds neutrons together, rather would the strong force hold individual neutrons together in a solid mass, preventing their decay if one could somehow put them together in a lab?

How can i detect the thermal neutron, E = 0.025 Ev, by MCNP using CUToff Or PHYS:N cards?

The time rate of change of neutron abundance ##X_n## is given by $$\frac{dX_n}{dt} = \lambda - (\lambda + \hat\lambda)X_n$$ where ##\lambda## is neutron production rate per proton and ##\hat\lambda## is neutron destruction rate per neutron. Given the values of ##\lambda## and ##\hat\lambda## at...

I was listening to a Star Date podcast regarding the constellation Vulpecula and learned about the discovery of pulsars and neutron stars. https://stardate.org/radio/program/2023-03-19 The first neutron star was discovered in Vulpecula in 1967. https://en.wikipedia.org/wiki/PSR_B1919+21 In...

I'm trying to understand why neutrons don't just continually bind into large masses. As I understand it proton binding in a nucleus is governed mostly by the strong nuclear force which attracts at close distance and electromagnet force that repels. So for protons to bind, they must have enough...

The Neutron is the rocket that Rocket Lab intends to compete with SpaceX's Falcon9. Still in development Rocket Lab is planning to use composites for tankage and airframe. Didn't SpaceX try this for the Falcon but abandoned it in favor of proprietary stainless steel...

If a neutron star and an anti neutron star collided, would they 1) completely annihilate each other, 2) form a black hole, or 3) partially annihilate each other with the remaining stars being pushed away from each other by the energy created?

Type 1a supernovas unbind a white dwarf. Is there some theoretically possible scenario in which a neutron star could be unbound and thus turned into degenerate matter or even regular matter? For example, by a high speed glancing collision with another neutron star or by tidal disruption by a...

could this explains the 3rd peak of the CMB and dark matter cold Primordial neutron star High Energy Physics - Phenomenology [Submitted on 7 Sep 2022 (v1), last revised 12 Sep 2022 (this version, v2)] Primordial neutron star; a new candidate of dark matter M. Yoshimura Z-boson exchange...

Basically, after seeing a meteor transit our atmosphere below 30,000 feet altitude too fast for my eyes to register yet leaving what looked like a beam of plasma from hanging from 1 side of the sky to the other for 3 seconds which I realized was a trail of smashed atoms of the atmosphere that...

Probably a misguided question, but would the intense magnetic field of a magnetar increase the overall pull an object would feel at the surface of the magnetar as compared to a regular neutron star? Or would it possibly lessen the amount of gravitational pull the object would feel at the...

Hi, i would like to write my own MC code in order to simulate the transport of Neutrons in Nuclear reactors. I know the basics of MC and i have already written a code for homogeneus reactors, my problem is the generalization to more complex geometries made of different materials, such as fuel...

Hi, I'm reading Chapter 2-II of of Duderstadt & Hamilton's "Nuclear Reactor analysis". In the section "Differential scattering cross sections with upscattering" it is discussed the situation in which neutrons suffers elastic scattering collisions in a hydrogen gas at finite temperature T and the...

I read this - https://www.sciencedaily.com/releases/2018/01/180116093650.htm And I see this - "However, there are indications that a neutron star with a maximum mass would collapse to a black hole if even just a single neutron were added." And I think the maximum mass of a neutron star is...

When we read about the mass transfer between neutron star pairs in a binary system, how is it that the one receiving the matter can increase its spin rate. Adding mass to a spinning object ought to slow due to conservation of momentum. Where does the energy come from?

When a photon emitted by a distant galaxy travels across space and is detected at a later time when the universe has expanded by a factor of 2, its wavelength, frequency, energy and momentum are all changed by a factor of 2. If a neutron is emitted with energy E and momentum p and is also...

When we learn about the scattering of a particle, the context is usually a charge shooting towards a Coulomb potential. With some assumptions, we can derive the scattering cross-section pretty reasonably. Therefore, the scattering cross-section of different elements in X-ray spectroscopy is...

I read this from Nasa's website: "Within the first second after the Big Bang, the temperature had fallen considerably, but was still very hot - about 100 billion Kelvin (1011 K). At this temperature, protons, electrons and neutrons had formed, but they moved with too much energy to form atoms...

I am studying the synthesis of FDG for a job interview. The process of creating the F-18 used in FDG involves the collision of O-18 with an accelerated proton -- the proton kicks out a neutron and everything adds up. I am just wondering why a neutron is specifically knocked out, why wouldn't...

Dear Community, I am having a question. I have developed a simple code to perform iteration power algorithm and find the keff value of a system. However, it is not still totally clear in my mind if I have to normalize all my scores by the eigenvalue, i.e. multiply by the keff (fluxes, power...

Assumptions: 1) Fusion reactors are easily obtainable. Every spacecraft or hover-car has one. 2) Fusion reactors are neutron sources. 3) Neutron sources are the "difficult bit" in the enrichment of uranium and plutonium. 4) Uranium and plutonium are "freely" available in asteroids or...

How did you find PF?: duckduckGo search. My math is very weak and I don't like explanations done using math. I read books with very little math. I try to use reason based on what I've read. My understanding is time slows down in gravity and it will actually stop at the event horizon (see...

I understand that gravity causes a neutron star larger than about 10 solar masses to collapse into a black hole. I also understand that gravity is the weakest of the four forces. So I find this counterintuitive and I'm puzzled that why is it gravity that causes the collapse and NOT the strong...

Finding the neutrons per second. Uncluttering the question: ##P = 6 \times 10^{7} J/s, E_{1} = 149.7 MeV/event, A = 10^{-4} m^{2}, R = 5 m ##. Number of events per second = ##\frac{P}{E_{1}}## = escaping neutrons per second Area of ##5m## sphere around reactor = ## 4 \pi R^{2} ## Fraction of...

Hello fellow physicists, I have a homework assignment which is to make a scientific essay (10-15 pages long) on neutron scattering in solid state physics. Our teacher is kind of the worse and he hasn't specified what he wants it on. He just said what I'm telling you: "An essay on neutron...

Greetings All, Well, this is the question from my 9 y.o. son: what will happen if a famous Everest heavy spoon of neutron star matter is actually removed from the star? I am inclining to his version that it will explode rather quickly, e.g. neutrons will quickly decay into protons-electrons...

I've been reading up on neutron embrittlement lately. However I go onto the DOE's website, and they are now saying that there really is no technical limit to how long a reactor can stay operational. Eventually I believe in the next 100 years because of embrittlement, reactors will have to be...

https://www.sciencealert.com/neutron-star-collisions-may-not-be-making-much-gold-after-all

λ^2=h^2/m^2v^2 =h^2/2/(m^2v^2/2) =h^2/2/(Km) =h^2/2Km

This BBC article posts no references so I wonder if anyone has any idea how significant it is? https://www.bbc.com/news/science-environment-53151106

Hey everyone, I've got a question on converting bound protons into neutrons. a. What are some methods used to achieve the proton-to-neutron conversion in atomic nuclei? I'm familiar with particle scattering off a proton in the nucleus. I'm also aware of (n,p) reactions. Are there any other...

Hi, Which force does govern the neutron elastic scattering and capture reactions? It seems to me it is the strong nuclear force, but I am not sure about that.Thanks.

Supposing the total mass of a stationary, non rotating Neutron Star is just one Kg below the mass required to form a black hole. Based on the wiki reference below the Schwarzschild radius must be just beneath the surface of the Neutron Star sphere. Now supposing an object with a mass of one Kg...

So I am reading a book "Fundamentals of Nuclear reactor physics" by Elmer E. Lewis On page 37 it talks about neutron interactions. some sentences I feel are left a bit short so let me rephrase here and hopefully get a clear answer. We have a neutron with a given kinetic energy and bunch of...

Physically speaking, why the insides of the least massive black hole should be any different from the heaviest possible neutron star?

Neutron stars have surface temperatures of 1,000,000 degrees K. Yet they are not creating energy like a normal star. They are just cooling off. How long does it take for such a star to cool to room temperature, 300 degrees K.?

For instance let's take that a neutron star mass is so high that the gravitational force is more than the coulumb force. If this happens then then the electrons will go down and alpha particle will be left . This is not observed in the star so how will the particle stay normal By the way I am...