Questions tagged [nucleosynthesis]
Nucleosynthesis is the process by which stars create heavier elements from hydrogen and helium
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How can we model the primordial Universe while the interior of a neutron star and comparable states of matter are still mostly unknown?
There is something I never quite understood about the physics of the primordial Universe. There are states of matter at high temperature/high pressure that are still, today, poorly understood. The ...
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Explain what happens in the alpha rich freeze out phase of a core collapse supernova(ccSNe) and which reactions takes place
In a core collapse supernova many nuclear reactions takes place and one of them is phase known as alpha rich freeze out phase, it is said to be very important in the production of alpha rich heavy ...
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Artificial Nucleosynthesis
Is it possible to artificially turn hydrogen into helium, let's say, and then go from helium to lithium and so on? I know that fusion reactors do that by fusing deuterium and tritium. Could this be a ...
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When a proton and neutron fuse in Big Bang Nucleosynthesis, do they emit a virtual neutral pion that emits two photons?
In Big Bang Nucleosynthesis, when a proton and neutron fuse to form a deuteron, how does the binding energy get shed? The binding is remanent strong nuclear force so does it emit a virtual neutral ...
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Power from CNO Cycle Fusion
There are all sorts of projects trying to get power from fusion reactions.
The best known and funded are the Tokamaks, big expensive crush Deuterium and Tritium (He3 sometimes) plasmas and spew ...
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Confusion about energy conservation for fusion and fission (binding energy and $Q$-value)
In a nuclear reaction, a system consisting of a nucleus or nuclei lose mass, and this mass gets turned into energy, which is quantified by $E=mc^{2}$. But I'm conceptually confused. According to ...
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Why can we make those approximations regarding the Big Bang Nucleosynthesis (BBN)?
(About neutron decoupling) Consider
$$p+e^{-}\rightarrow n+\nu_{e}.$$
In particular if we consider temperatures about $\simeq1\mbox{MeV}$ both neutrons and protons are non relativistic and we can find ...
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How do nuclear physicists know for certain if a very short-lived nucleus has been formed (a new isotope)?
Some very short-lived nuclides (sometimes called 'resonances') are nevertheless considered to have actually existed, if only very very briefly....
How do nuclear physicists know the isotope actually ...
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Why is the deuterium bottleneck temperature 0.1 MeV?
During big bang nucleosynthesis (BBN), deuterium has a lower binding energy per nucleon (~1.1 MeV) than the other similar nuclei, and so prevents heavy elements from forming until the temperature ...
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Solving this first-order differential equation for neutron abundance using given data
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 ...
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If dark matter was created in the early universe and its formation released energy, is there any evidence of that energy in the cmb?
When atomic nuclei fuse, energy is released. Is there anything about the CMB energy distribution that suggests that dark matter could have formed from other particles that released energy?
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LCDM epoch or point where it fails
Nobody denies the currently success of the LCDM of cosmology. Recently, I wondered myself if there is a point or epoch (beyond the space-time singularity) where it breaks down. Does it fail at phase ...
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Why can't high-level nuclear waste be disposed of by bombarding troublesome isotopes with neutrons, protons and gamma rays (photodisintegration)?
Why can't isotopes with long half-lives be radiated with free protons, neutron radiation and gamma rays (photodisintegration) in order to transmutate those isotopes into something either stable (or ...
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Why is lithium burned at lower temperatures than hydrogen inside stars?
The destruction of lithium inside stars through the reaction
$$ ^{7}_{3}{\rm Li} + {\rm p} \rightarrow 2\ ^{4}_{2}{\rm He}$$
takes place at just $\sim 3\times 10^6$ K.
This is much lower than the ...
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How does absorbing a free thermal neutron convert nitrogen-14 into carbon-14? (Radiocarbon dating, etc.)
Why doesn't a nuclide of N-14 simply absorb the neutron created by cosmic rays or solar wind interacting with the atmosphere and become N-15, which is stable?
How or why does the resulting Nitrogen-15 ...
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