What is Neutron capture: Definition and 29 Discussions

Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, which are repelled electrostatically.Neutron capture plays a significant role in the cosmic nucleosynthesis of heavy elements. In stars it can proceed in two ways: as a rapid process (r-process) or a slow process (s-process). Nuclei of masses greater than 56 cannot be formed by thermonuclear reactions (i.e., by nuclear fusion) but can be formed by neutron capture.
Neutron capture on protons yields a line at 2.223 MeV predicted and commonly observed in solar flares.

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  1. S

    I Inelastic vs. neutron capture

    For neutron inelastic interaction, the nucleus de-excites by emitting gamma-rays or charged particles. However, for neutron capture, the nucleus de-excites by emitting gamma-rays only. Why does the nucleus in the neutron capture interaction de-excite by only emitting gamma-rays? why not by...
  2. S

    What are the rate equations for neutron capture on unstable nuclei B?

    Summary: Problem: nuclear physics, neutron capture In the problem one should calculate time dependence of number of nuclei. Problem statement: Neutron beam radiates sample A with initial number of atoms N0. With neutron capture nuclei (cores) of A are transitioning to nuclei B (they are just...
  3. dRic2

    Neutron capture and fission reaction

    Hi, I've been wondering about this a lot and I didn't find a satisfactory answer by myself. My professor said that in order to promote a fission reaction you need to provide a certain amount of energy (like in a chemical reaction you need to overcome the activation energy) and the easiest way...
  4. O

    I U-235 thermal neutron capture gamma ray

    Hi, When U-235 captures a neutron, it may end up with a fission reaction or an excited U-236 isotope. This U-236 emits gamma rays as it goes to its ground state. What I want to learn is that how much is the contribution of these gamma rays' energy to overall fission energy. I checked the...
  5. Kirk Truax

    What is the macroscopic cross section for natural uranium to thermal neutrons?

    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
  6. S

    I What neutron energy regime is dominant with neutron capture?

    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...
  7. M

    Exploring the Curious Case of He-3 Neutron Absorption and Fission into H-3 and H

    I'm curious, why does Helium-3 fission into H-3 and H upon neutron absorption? Surely the He-4 nucleus configuration is more stable? I get that the energy release may be what splits the nucleus, because it releases quite a lot of energy if it were to simply absorb the neutron.
  8. Phaeous

    Of Lost Neutrons Within Reactors

    How is a continuous chain reaction maintained within a moderator if it is not fissile material? Are the fissile materials mixed with the moderator or are they coalesced at the center of the surrounding moderator? If it is the latter, how would the surrounding moderator allow fissile material to...
  9. T

    Neutron Capture in Hydrogen Fusion Reactor

    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...
  10. J

    How can lithium be used for cold fusion through thermal neutron activation?

    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?
  11. M

    Boron Neutron Capture Therapy

    Hello All I'm doing my theses in BNCT(Boron neutron capture therapy).I did it with 2.5 Mev imaginary accelerator. there are many reactors to compare my data with theirs.but Unfortunately I couldn't find some Real accelerators based on BNCT to compare my MCNP-X output data with theirs. could u...
  12. R

    In-flight neutron capture by Cobalt-59

    Can anyone help me with an approximate answer to this or point me in the direction of avenues to get an answer to this? This has practical applications and is potentially worrying. Roughly how much (or how many atoms) of cobalt-59 exposed to the average neutron radiation at in-flight...
  13. M

    BNCT(Boron Neutron Capture Therapy)

    My research is about Design and modeling of beam tube of nuclear reactor for BNCT(Boron Neutron Capture Therapy) application and I need some journals and related books about it.
  14. R

    Understanding Gamma-Ray Emission in Gadolinium Neutron Capture

    neutron capture --> gamma's Someone could explain me how neutron capture in Gadolinium happens? If a neutron is captured, an energy of about 8 Mev is released in form of gamma-ray cascade (Ʃγ). But... how many gammas are released? I believe the answer will be in form of probability...
  15. P

    Neutron capture cross section of tritium is zero

    I wish to verify a couple of assertions. From the NNDC and other references, it appears that the neutron capture cross section of 3H (Tritium) is zero to a first approximation. This holds true for all neutron energies, including cold neutrons. These statements are equivalent to asserting that 4H...
  16. M

    Why do different nuclei need different neutron speed for neutron capture?

    Why do different nuclei need different neutron speed to achieve fission?? My understanding is that U-235 requires a thermal neutron in order to be likely to cause a fission reaction, however Pu-239 requires the additional energy of a fast neutron in order to cause the nucleus to undergo fission...
  17. K

    Thermal Neutron Capture from 55Mn to 56Mn

    Homework Statement In a reactor, we're making 56Mn by inducing thermal neutron capture. 2g sample of 55Mn is put into the reactor which has a flux of thermal neutrons of 3E13 neutrons/cm^2*s Sample is in the reactor for 8 hours and then removed. a. Calculate the amount and activity of...
  18. edpell

    Calculating the Potential Well of Neutron Capture by the Strong Force

    If I have a low energy neutron and I bring it close to a nucleus it will be captured when it gets close enough. How can I calculate the shape of the potential well of the nucleus for neutron capture? I keep reading that it is due to the strong force, which I agree with. But it is some...
  19. J

    Neutron Capture Cross Section Dependence on Target Material Temperature

    So I have been reading about the cross section of neutron capture and have been reading about how the cross section for neutrons in a given material depends on neutron energy, the most important factor obviously. But I have not seen as much information on how, for a neutron of a given thermal...
  20. P

    Heat released in neutron capture by boron

    I am working on some neutron experiments and have to calculate the heat released in the boron neutron capture 10B + 1n - > Li + Alpha particle The reaction has a Q value of 2.31 MeV. Is this entire energy converted to heat? Also, in the two types of reactions of neutron with Boron...
  21. A

    [Special Relativity]Slow Neutron Capture

    Homework Statement A helium-4 nucleus (rest mass 4.00151 u) is formed when a helium-3 nucleus (rest mass 3.01493 u), stationary in the laboratory frame, captures a slow neutron (rest mass 1.00867 u), in the following reaction. 3He+n→4 He+γ Determine the energy (in MeV) of the γ-ray in the...
  22. P

    Does capturing neutrons turn hydrogen into deuterium and affect the experiment?

    Hi all. I am going to be doing an experiment involving neutron scatter. I am going to be firing fast neutrons into water and then detecting the thermal neutrons scattered. I am also going to look into thermal neutron capture where the hydrogen atom captures the thermal neutron and gives off a...
  23. I

    Boron Neutron Capture Therapy (B10->B11)

    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...
  24. N

    Neutron capture by light nuclei

    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...
  25. M

    U-238 Neutron Capture: Clarifying Misconceptions about Fast and Slow Neutrons

    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.??
  26. M

    (Neutron capture) cross section

    Cross section means the effective size of a nucleus for capturing a neutron, am I right? But what makes the cross sections for different nucleus different? I am a bit puzzled, why the cross section for Boron(for example) is so high?
  27. G

    Ba-133 Neutron Capture Cross Section - Thermal & Excited States

    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.
  28. H

    How to find neutron capture and fission cross section

    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?
  29. P

    What Is Produced When Nickel-60 Captures a Neutron?

    taking a set of questions and came across this one: "Capture of a neutron by nickel-60 produces a proton and what new element or isotope ? " I thought it was copper-61 since it goes through beta decay as indicated by the proton but supposedly it is not... please help