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

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What's the slowest nuclear decay rate that's been measurably linked with a narrow energy linewidth?

As was explained in the question What is the relation between the half-time and the line-width of a radioactive nucleus?, the half-life $\tau$ of an unstable nucleus is related to the linewidth ...
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1answer
115 views

What is the relation between the half-time and the line-width of a radioactive nucleus?

Are they inversely proportional to each other? This is the case for the atoms, I think. The problem is that, for those isotopes like uranium 238, the half-time is as long as 4.4 billion years, and ...
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2answers
168 views

Why would two protons repel?

I understand that two protons would repel due to them both being positively charged, however, wouldn't the strong force act on the two protons pulling them together? Would this mean that in this case ...
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33 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 ...
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1answer
46 views

Big bang theory

How much energy and heat were produced by the big bang? I'm reading Bill Bryson's Short history.... He mentioned a point that to forage light elements like hydrogen, helium and lithium into elements ...
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1answer
163 views

What is an 'S-factor' in nuclear physics?

I have seen the "S-factor" in many places, but I've never read an explanation of what it actually is. I have read that it is related to the cross-section of a reaction, but that's about it.
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3answers
68 views

Binding energies of Be

Just a quick question. How does Beryllium 8 decay into 2 alpha particles? Beryllium 8 has a binding energy of 56.499508 Mev An alpha particle has a binding energy of 28.3 so two of these would have ...
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1answer
71 views

What does 'channel' mean?

I see many plots like the following that graph counts per channel, I know what a 'count' is, but I don't know what a 'channel' is. Could somebody please explain to me? My guess is that it is that ...
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33 views

What is a threshold/subthreshold state and resonance?

I understand what a 'state' is for a quantum mechanical system, but upon reading a paper on reducing the error for a particular nuclear reaction rate I saw the following sentence. "The extrapolation ...
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0answers
24 views

How to express the differentiation of an antisymmetric matrix (the HFB pairing field)?

I'm trying to wrap my head around the differentiation of antisymmetric matrices in the context of Hartree-Fock-Bogoliubov (HFB) mean-field theory (see also e.g. Ring & Schuck, Blaizot & Ripka, ...
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1answer
172 views

How would the explosion from a Pure Fusion Bomb differ from the explosion from a Fission Nuclear Bomb?

Suppose we have the technology to create high enough temperatures and pressures inside a confined space to fuse together deuterium and tritium, and create a Pure Fusion Bomb. How would the explosion ...
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1answer
247 views

How hot is Plutonium-238 in Radioisotope Thermoelectric Generators (RTGs)?

As I understand it, Plutonium-238 is used to provide power through heat generation in radioisotope thermoelectric generators. My question is... how hot is a pellet of Plutonium-238? Does the heat ...
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1answer
49 views

r-process: Is it correct to talk about “primary” and “secondary” r-processes?

This website, written in 1994, makes a differentiation between the "primary" and "secondary" r-processes in the context of astrophysics. As far as I can tell the main difference between the primary ...
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0answers
20 views

Proper nuclear reaction notation for arbitrary species

I am wondering the common way to write a nuclear reaction for an arbitrary species. For instance, for neutron capture on a species $X$: $$^{A}_ZX + n \rightarrow ^{A+1}_{\ \ \ \ \ Z}X'.$$ Is this ...
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0answers
14 views

only one material (meta)stable at extreme pressures?

Is the pressure at the center of a neutron star so high that everything is crushed into neutronium, no matter what the original elements were? What is the highest pressure (at low/moderate ...
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1answer
552 views

Deriving Gamow factor for potential with effective centrifugal potential term

I am looking at deriving an expression for the Gamow factor for $\alpha$-decay. I understand that the potential is the sum of the nuclear, electric and effective potentials: $$V(r) = V_N(r)+V_c(r) ...
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1answer
47 views

Why does a spinning nucleon generate a magnetic field?

I am trying to understand how NMR works, but I am not sure why a spinning nucleon produces a magnetic field. Is this a consequence of the quark structure inside?
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4answers
2k views

Could we make things out of newly discovered particles?

Right now, all of the "stuff" that has been created in the world is made of protons, electrons, and neutrons. I'm aware that particles other than these have much shorter lifetimes. But I've also heard ...
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1answer
206 views

Electron scattering to measure the nuclear radius

I have been taught that you can find out the size of a nucleus of an atom by firing electrons at high velocities at the atom. This causing scattering due the positive charge of the nucleus and ...
2
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4answers
162 views

Mass Defect…cause and origin?

What makes it occur? How do the protons and nucleus know that they have to lose mass to produce energy...? And is the mass of a compressed Spring more than an uncompressed one?? does a body which has ...
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1answer
269 views

The original thorium reactor?

With lunar thorium being common, and heavier than iron or nickel, does earth's core have the the occasional nuclear reaction?
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1answer
201 views

Charge on the remaining atom after Alpha decay

In radioactive alpha decay, a helium atom is shown to be released. However, I was told that only thing released is a helium nucleus. If so, then it should leave two of its electrons in the atom ...
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2answers
308 views

Do all isotopes have a half life? [duplicate]

I understand that some isotopes of an element have a shorter half life, and decay more quickly into other elements. Other isotopes are described as stable and no half life is stated. For elements that ...
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40 views

Energy needed for exoergic nuclear reaction

To initiate endoergic nuclear reaction (negative Q Value)minimum energy is supplied which is slightly more than Q value. Then what will be the energy needed for intiating exoergic nuclear reaction ...
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0answers
33 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 ...
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37 views

Gain of entropy

Can we really interpretate third thermodynamic law as unconditional gain of entropy of closed system? For example, when they separate U 235, they drive the mix on the pressure barrier, so heavier U ...
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28 views

Relativistic non-linear Walecka model

What is meant by a relativistic non-linear Walecka model? What are some various sources to study it? [And why cannot Google show a satisfactory result to such a simple question?]
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1answer
199 views

How much pressure would be needed to contain a 1 gigaton nuclear bomb explosion within a sphere of one meter radius?

How much pressure would be needed to contain the largest human exploitable nuclear bomb within a sphere of one radius? Also would it be possible to create a magnetic field that controlled some ...
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1answer
51 views

Why is there not much research into nuclear physics with plasmas?

There is a lot of research and theory around fusion reactions with plasma, but is there a reason why plasmas cannot be used for researching other nuclear reactions, either in the lab or from ...
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1answer
342 views

Why doesn't the deuterium nucleus have spin 0?

A deuterium nucleus is composed of a proton and a neutron. Both have spin 1/2 so I would expect the deuterium to have two possible spins: 1 for the triplet and 0 for the singlet. But apparently ...
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0answers
47 views

Why spin-$\frac{1}{2}$ nuclei have zero electric quadrupole moment?

Why spin-$\frac{1}{2}$ nuclei have zero electric quadrupole moment? How to calculate in general?
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1answer
76 views

Would it be possible to “recycle” nuclear warheads into nuclear energy? [closed]

The number of nuclear warheads in the world is estimated (!) to be over 16,000. [0] Surely, this stockpile represents a massive threat to humanity. My question is simple. Can we repurpose these ...
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2answers
156 views

What is the main thermal energy source for a protostar, the contraction or the deuterium burning energy?

According to the virial theorem, when a protostar contracts, half of the gravitational potential energy is radiated and half is kept as kinetic energy of the falling material which in turn heats the ...
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36 views

Rotational wave funtion of a nucleus

The rotational hamiltonian of an axially symmetric rotor is, in the intrinsic frame of the body, where the moment of inertia is diagonal, $$\mathcal{H} = \frac{\hslash^2}{2I} \left(J^2 - I_3^2\right) ...
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1answer
31 views

Where can I find a list of approximate excitation energies?

I would like to know the excitation energies for the known states of various nuclides. Is there a list somewhere that has this documented? I can't seem to find them easily for many nuclides. Maybe I ...
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1answer
1k views

What happens to Protons and Electrons when a Neutron star forms?

What happens to Protons and Electrons when a Neutron star forms? At some point gravity overcomes the Pauli Exclusion Principle ( I assume) and they are all forced together. What happens in the ...
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2answers
433 views

What makes a nucleus unstable?

My question is simply that - what makes a nucleus unstable? What exactly causes a nucleus to start breaking apart in the first place? Is it the Coulomb force between the neighboring protons? I'm just ...
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29 views

Why does U-235 split into barium and krypton in nuclear reactors? [duplicate]

For my chemistry project I have found the typical fission reaction which occurs in nuclear power plants is when nuclear fuel rods are bombarded with neutrons, splitting U-235 into isotopes barium and ...
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1answer
47 views

Why is 0 $\nu \beta\beta$ decay often written with electron emission and not positron?

According to http://www.cobra-experiment.org/double_beta_decay/ I can see that double $\beta$+ decay is possible, but I often find neutrinoless double beta sources with the double $\beta$- decay ...
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4answers
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Are atoms made of protons, electrons and neutrinos?

If neutrons decay into proton, electron and (anti)neutrino of electron type, then is it safe to say that atoms are protons, electrons and neutrinos?
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136 views

Do electrons get accelerated or decelerated by the atoms of the anode during X-rays production?

The electrons striking the anode get deflected by the heavy nucleus. Though the speed may or may not change, the direction of motion changes which leads to acceleration. The charged particles emit ...
2
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1answer
50 views

Why do NNLC and NIST appear to give different values for the mass energy of the deuteron?

There is a problem with data that I've obtained over the internet. Here are the two sources of information from which I'm retrieving my data. NNLC and NIST On NIST, I have read that the mass excess ...
31
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2answers
3k views

Why did “tickling the dragons tail” by Louis Slotin not cause an explosion?

I have been reading the excellent Command and Control by Eric Schlosser and discovered more about Louis Slotin's experiment with "tickling the dragons tail" and the infamous Demon Core. What I don't ...
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0answers
31 views

The Form Factor in Nuclear physics

We know $$F(\vec{q})=\int e^{i\vec{q}.\vec{r}} \rho(r^\prime) dv^\prime$$ where $\vec{q}$ is the momentum change of scattering electron. But what is the physical meaning of it ?!
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1answer
67 views

Identification of massless, chargeless $x$ in a nuclear reaction

On Friday, we had our Physics test. We (the tenth grade students) have the basic introduction to Radioactivity and a few nuclear reactions in our syllabus. In the test, the following question was ...
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4answers
268 views

What does the exponential decay constant depend on?

We know the law of radioactivity: $$N=N_0e^{-\lambda t}$$ where $\lambda$ is the exponential decay constant. My question is: This constant depends of what?
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4answers
120 views

Is an atom charged after undergoing beta emission?

After beta emission, an atom's mass number remains the same while the number of protons increases by one. As far as I know, the beta particle (electron) is too energetic to be recaptured. If this is ...
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1answer
116 views

How do scientists estimate elemental-abundance in the universe?

I understand how cosmological observations can estimate the amount of 'baryonic matter' in the universe, but what I don't understand is how scientists can estimate the abundance of a particular ...
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2answers
188 views

Why are the dineutron and diproton unbound?

It is known that there is no diproton and dineutron nuclei. Does this mean that two protons or neutrons are not actually attracted to each other? Even if the attraction was weak, wouldn't it cause ...
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1answer
63 views

Ambiguity in ordering of isospin states for Clebsch-Gordan coefficients

In studying isospin for nuclear physics, I am confused a bit by an ambiguity I found. If a process that goes from $K^- + p \rightarrow \Sigma^0+ \pi^0$, I can write the isospin for the left hand side ...