Questions tagged [nuclear-physics]

Nuclear physics is the study of the composition, behavior and interaction of atomic nuclei and their constituent parts.

296 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
9
votes
0answers
446 views

Integration & bremsstrahlung calculation

In this paper (relevant pdf section) that I'm reading, involving the calculation of bremsstrahlung in electron proton scattering (diagram below), the author calculates the integral over outgoing ...
8
votes
0answers
666 views

What is the theoretical efficiency of fusion?

What is the theoretical limit of the amount of energy that can be extracted from a fusion reaction? I am not talking about the practical efficiency of a reactor, but rather what fraction of the mass-...
8
votes
0answers
157 views

Why does strong interaction increase with distance?

I read numerous times that strong interaction increases with distance. But how can one actually derive the force-distance relation from the lagrangian (quark field + gluon field + gauge coupling)? ...
8
votes
0answers
163 views

Does quark color contribute to “spin degeneracy” for QGP calculations?

Like the title say, does quark color matter in counting contributions in a early universe plasma (QGP), as when adding up the total plasma energy density, or is it just spin? The book I have (Pathria) ...
6
votes
0answers
87 views

Is it a coincidence that Big Bang nucleosynthesis lasted about one free neutron half-life?

The free neutron half-life is about 10 minutes. Big Bang nucleosynthesis, which mostly involves protons and neutrons interacting, lasted about 20 minutes. Question: Is it a coincidence that these ...
5
votes
0answers
56 views

Plum-pudding atomic physics in higher dimensions?

It is established that "normal" electron orbitals are not stable in more than 3 spatial dimensions, as the available energy levels become unbounded from below. However, this result only applies given ...
5
votes
0answers
213 views

On the construction of atomic kernels

Can anybody point me to an English translation of Heisenberg’s three part paper Über den Bau der Atomkerne? Failing that, can you point me to a non-paywalled German version of part III? I have parts ...
5
votes
0answers
3k views

Energy Levels of 3D Isotropic Harmonic Oscillator (Nuclear Shell Model)

One simple way of detailing the very basic structure of the nuclear shell model involves placing the nucleons in a 3D isotropic oscillator. It's easy to show that the energy eigenvalues are $E = \...
4
votes
1answer
69 views

What drives the charge separation in atoms?

In atoms charges are neatly separated. Instead of pairing which seems natural they all stick together with their peers. What drives this peer behaviour? Why is it stable?
4
votes
0answers
72 views

What processes contribute to non-relativistic proton-antiproton collsions (annihilation)

I wonder what the dominant contributions of nuclear interaction to non-relativistic proton-antiproton annihilation are (I mean that the proton and antiproton are non-relativistic. The products might ...
3
votes
0answers
33 views

Intermediate product of CNO cycle

CNO cycle of stellar nucleosynthesis involves several steps in which different isotopes of Carbon, Nitrogen, and Oxygen are transmuted into each other when hit by a ...
3
votes
0answers
74 views

Ground state of an odd, deformed nucleus: intuition for what happens to the $j_x$ and $j_y$ of the odd particle

This is something that relates closely to my long-ago PhD research, and it's a point that I never satisfied myself thoroughly on. I have a copy of a standard text that covers this general topic, de ...
3
votes
1answer
43 views

Thickness of a target bombarded with deuterium

I need to calculate de thickness of a sheet of Zinc that is being bombarded by deuterium nuclei. I'm given that the fraction of nuclei dispersed below $\theta=90º$ with $T=8MeV$ is $0.9999$ and the ...
3
votes
0answers
26 views

Is there more iron or nickle in the core of a pre-supernova star?

For stars that undergo core collapse (leading to a core-collapse supernova or direct blackhole formation), the final stage of nuclear burning is silicon burning. Most online references I've found ...
3
votes
0answers
54 views

What Exactly is the “Optical Limit” in High energy hadronic collisions?

I am a little confused about what "Optical Limit" means in the context of hadronic diffraction. In some text it says that is the case where $A$, $B$ goes to infinity, where $A$ and $B$ are the ...
3
votes
0answers
71 views

Which theory do we use when dealing with the center of a star?

The center of a black hole is known as being one of the locations in spacetime that needs an unification theory between quantum physics and general relativity, because of having a large mass in a ...
3
votes
0answers
215 views

Protons and Neutrons inside the Nucleus

I know that the strong nuclear force holds quarks together to form protons and neutrons, as long as their color charges add up to white, so then how does the strong force simultaneously hold the ...
3
votes
0answers
239 views

Can daughter nuclei from fission be lighter than Fe-56?

In a typical nuclear fission reaction, a heavy nucleus decays into daughter nuclei which are lighter and have higher binding energy per nucleon. For example: ...
3
votes
0answers
2k views

Spin Parity calculation of Ne-21 using nuclear shell model

Neon 21 has 10 protons and 11 neutrons, therefore using the nuclear shell model (i.e. https://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Shells.png/220px-Shells.png) it seems it should have 2 ...
3
votes
0answers
207 views

Why is the nucleon axial charge a charge?

Lets take a look at the definition of the nucleon axial charge $g_A$ $\langle p|A^a_\mu|p\rangle = g_A \bar u(p)\gamma_\mu\gamma_5\tau^au(p)$ with the QCD axial current $A^a_\mu=\bar\psi\gamma_\mu\...
3
votes
0answers
47 views

References or resource recommendation for the mathematics concerning fission

I am working on a statistical problem that appears similar (in some respects...) to nuclear fission. I am interested in the properties of a system undergoing fission around, or near, delayed ...
3
votes
0answers
497 views

physical intuition behind quasi-bound state formation in feshbach resonance

In Feshbach resonance, by scattering theory formalism it is found that the resonance in cross-section happens when bound state energy of the closed channel is near to the scattering state energy of ...
3
votes
0answers
102 views

What fraction of nuclear excited states are known?

I was reading a paper today claiming observation of a new $2^+$ state in $^{12}\mbox{C}$, which would correspond to a sort of rotationally excited Hoyle state. Looking at NuDat reveals that this ...
3
votes
2answers
82 views

What exactly is binding energy?

I've been reading on radioactivity but along the way I got confused, if binding energy is the amount of energy used in holding the nucleus together then why is binding energy also the amount of energy ...
3
votes
2answers
3k views

Strong force, where is the separation?

In class I was given a diagram like this: (albeit without the electrostatic force line) (source: boredofstudies.org) However, the teacher told us the nucleons are typically separated when the ...
2
votes
0answers
32 views

Wavefunction for the deuteron's ground state

I was reading Blatt & Weisskopf's Theoretical Nuclear Physics (1979) and on the II.Two-Body Problems at Low Energies chapter, page 100, they say: The wave function for the composite state (the ...
2
votes
0answers
62 views

Why is the D+P fusion reaction not considered for large-scale power production?

I know that D+D (fusion of deuterium + deuterium nuclei) as well as D+T (fusion of deuterium and tritium nuclei) are the reactions most commonly considered for large-scale power production. Why not D+...
2
votes
1answer
77 views

Why is the isotope of lead-206 stable against alpha decay?

The mass of Lead-206 is larger than that of Mercury-202 + Helium-4. Why is then Lead-206 stable against alpha decay? I have heard that the beta-decay can stabilize a nucleus against alpha decay, and ...
2
votes
0answers
34 views

$2\nu\beta\beta$ vs. $2\nu$ECEC

Considering the recent observation of two-neutrino double electron capture ($2\nu$ECEC) by the XENON Experiment: https://arxiv.org/abs/1904.11002 I was wondering why the half-life of this process is ...
2
votes
0answers
35 views

Isn't it entropy (disorderliness) that every atom in the universe is not of iron Fe?

The concept of mass defect and binding energy Iron has most mass defect and the greatest binding energy. It has the most stable nuclei. Nuclei with higher atomic number than iron undergo fission ...
2
votes
0answers
16 views

What distinguishes a duoplasmatron from simpler methods of ionizing gases?

I've been looking at duoplasmatron designs and am not sure what makes the basic function of a duoplasmatron different from simply ionizing H2 gas by sending an arc discharge/electric current through ...
2
votes
0answers
38 views

Geant 4, simulate Tc-99m decay

I have a setup of Monte Carlo simulations in Geant4, and I'm able to simulate radioactive events from isotopes such as I-131 and F-18, which are defined in the RadioactiveDecayData5.2 files. Tc-99m ...
2
votes
1answer
129 views

Why Don't All Heavy Elements Decay into $^{62}\rm Ni$?

I read the question If we assume that protons don't decay, then will all matter ultimately decay into Iron-56 or into nickel-62?, but I have a different question concerning the decay that has ...
2
votes
0answers
70 views

Spin-parity states of $^{17}O$ and $^{19}O$

I am trying to understand a problem in a subnuclear physics course. The question is the following: The biggest difference between the low-lying states of $^{17}O$ and $^{19}O$ is that $^{19}O$ ...
2
votes
2answers
94 views

Why does it take less binding force to hold the two atoms that a uranium atom has split into?

When a Uranium atom splits into two there is a little bit of mass left that is equivalent to a big amount of energy (e=mc^2) and it explodes in fission It takes less binding force to keep the two ...
2
votes
1answer
82 views

Spallation of Lithium by GeV protons?

If you direct a beam of, say 400 keV protons, against a Lithium target, you induce fusion reactions. This is the well known Cockcroft-Walton experiment. Now I would like to ask if you can induce ...
2
votes
0answers
34 views

What is the meaning of the Wilson coefficients $C_{S,P,T}$ in the electron-nucleon interaction?

I am doing a project on electric dipole moments in supersymmetry. My background is in high energy physics, so I am having trouble fully grasping the nuclear interactions. Part of that includes ...
2
votes
1answer
93 views

Coulomb potential in nuclear fission?

In the case of symmetrical fission we must consider the Coulomb potential between the two nuclei : $$ E=k \frac{q^2}{r}= k \frac{(\frac{Ze}{2})^2}{2r_0 (\frac{a}{2})^{1/3}}= k \frac{2 ^ {1/3}}{8} ...
2
votes
0answers
96 views

How can we evaluate the ratio of abundance of Carbon to Li, Be and B?

In stars' nuclear processes, if the triple $\alpha$ reaction explain why Carbon is much more abundant than Li, Be, B, how can we evaluate the ration of abundance to ~$10^5$ times ? Is it possible to ...
2
votes
0answers
39 views

Inertial Reference Frames in Quantum Mechanics (and an application in NMR)

The four postulates of the Quantum Mechanics do not talk anything about the reference frame in which the Hamiltonian is built and also the measurements that we do. Is it that the postulates are valid ...
2
votes
1answer
210 views

Magnetic moments of nucleons

I was comparing my notes of the nuclear physics class (undergraduate level) on magnetic moments of nucleons with the Krane's explanation. In my notes I wrote that there are two types of magnetic ...
2
votes
0answers
74 views

What is the general form for the cross section and rate for orbital electron capture?

I want to derive the basic equations for the rate of electron capture, taking into account the relativistic kinematics explicitly $$p^{+}+e^{-}\rightarrow n^{0}+\nu_{e}$$ The idea is to treat ...
2
votes
0answers
341 views

Bethe-Bloch equation (for Stopping Power Calculations); Quantum Mechanical Derivation

Bethe-Bloch equation using quantum mechanical calculations is $$-\dfrac{\mathrm dE}{\mathrm dx} = 2 \pi N_{a} r_{e}^{2} m_{e} c^{2} \rho \dfrac{Z}{A} \dfrac{z^{2}}{\beta^{2}}\left[\ln\left(\dfrac{...
2
votes
1answer
70 views

When an element goes through nuclear decay, and the daughter product is reactive with the parent product, is there an immediate chemical reaction?

When fission occurs, there is a new daughter element. This can react with the parent material. 1. Does it, and if so, how quickly? 2. If not, why not?
2
votes
0answers
128 views

Obtaining partial decay constants from Gamow factors?

Consider the nuclide $^{190}\text{Pt}$, which is an alpha emitter. By using the Gamow calculation described here, I am able to obtain a rough approximation of the decay constant $\lambda$ for this ...
2
votes
0answers
79 views

Why do the masses of decay products affect the branching ratio?

Consider a particle $P$ of mass $100m$ (where $m$ is some unit). It can decay into either of two particle-antiparticle pairs: $P\to P_1\bar{P}_1$ with branching ratio $BR_1$, where $P_1$ has mass $...
2
votes
0answers
508 views

Fermi's theory of beta decay - Does Fermi's Hamiltonian have the wrong transformation properties?

I'm studying the theory of beta decays as proposed by Fermi in the 30's, and I found an inconsistency between the transformation properties that he claims for his Hamiltonian and the transformation ...
2
votes
0answers
49 views

Assigning values of angular momentum transfer

How do the shapes of the experimentally measured differential scattering or transfer cross sections help in assigning reliable angular momentum transfer values?
2
votes
0answers
249 views

Positive/negative octupole moment of nuclei?

Does octupole moment of nuclear charge distribution show any positive/negative character, like the quadrupole moment does? Quadrupole moment has prolate and oblate types, but what about ...
2
votes
0answers
29 views

Have the BaF2 scintillators a strong correlation with the input current that cause the shifting of the centroids in the distribution?

In gamma gamma correlation I suspect the presence of systematic error maybe caused by a non optimal voltage according to someone there is a quadratic correlation between centroids position in the ...