Questions tagged [nuclear-physics]

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

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Why low energy electron-proton colision cannot simply produce neutrons?

Can low energy electron-proton collision produce neutrons (and neutrinos)? I asked many of my physics teachers but they said that it would produce hydrogen atoms instead. Some explained this because ...
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Could a Λ or Σ baryon be stable inside a nucleus?

A common "cartoon model" of a nucleus is that there are a set of bound energy levels for the protons and a similar set of bound energy levels for the neutrons. The existence of these energy ...
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Why in the nuclide chart the $Q_{\alpha}$-value (the energy released in an alpha decay) is listed even for stable nuclides?

When I was studying some graphs I started comparing data with the nuclide chart of https://nds.iaea.org, and I noticed that even for nuclides that aren't typically alpha emitters, even for stable ...
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How to measure wavelength of gamma-rays

How can we experimentally measure the wavelength of gamma-rays, say for about 0.7MeV without knowing the exact energy and without measuring energy, i.e. sort of direct measurement.
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Can an alpha particle (or any charged particle) can penetrate through nucleus of gold atom?

Can an alpha particle (or any charged particle) can penetrate through nucleus of gold (or any other) atom ? Today I was watching a lecture on the "Estimation of Size of Nucleus" which was a ...
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Effective Hamiltonian in Heisenberg model

How can we divide the whole matrix into submatrices that we can write effective Hamiltonian on the Heisenberg model Based on Fundamentals of the Physics of Solids book (Volume I) written by Jen˝o ...
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Nuclear reactions in stars: tunneling?

Energy production in stars occurs mainly when a nucleus absorbs a proton or fuses with another nucleus. Some examples: (i) $\rm{p}(\rm{p},\rm{e}^+\nu)\rm{d}~$ and $~\rm{d}(\rm{p},\gamma)^3\rm{He}~$ ...
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Reactivity in nuclear fusion

In nuclear fusion, the graph of reactivity is shown as below. How can we explain that by increasing the temperature after a certain value, the reactivity decreases?
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Could there (at least theoretically) ever be a way to prevent radioactive atoms from decaying?

I mean, in such a way as to make it feasible to have a collectible sample of an element like astatine, francium, or protactinium (ignoring their chemical toxicity, which could probably be contained in ...
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Why do Xe-135 and Zr-88 have a surprisingly large thermal neutron capture cross-section?

Why do Xe-135 and Zr-88 have surprisingly large thermal neutron capture cross-sections? The probability that a nucleus will absorb a neutron—the neutron capture cross-section—is important to many ...
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Can fusors be used to turn Uranium 238 into Plutonium 239?

Since a Farnsworth–Hirsch fusor is apparently a good fast neutron source that is simple enough to build at home, why can't it be used by rogue states or even terrorists to turn non fissile U-238, ...
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Why is the isotope Nitrogen-14 formed preferentially in CNO-cycle stars? As opposed to N-15?

Most of the universe's nitrogen is formed in larger, main sequence stars using the CNO Cycle, right? But I cannot find a good, specific explanation as to why N-14, with odd numbers of both neutrons ...
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Mass changing form

I want to ask whether mass changes to charge or any other form in beta plus decay or minus decay because in beta plus decay up quark changes to down quark with formation of positron and neutrino, here ...
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$\beta$ decay paths question

Can the $\beta^-$ decay proceed by the absorption of a $W^{+}$ boson or the $\beta^+$ by the absorption of a $W^-$ boson? The $\beta^-$ decay is known as the decay of a $d$ quark into an $u$ quark and ...
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In the Tchernobyl nuclear plant of the 1986 accident, were there a secondary circuit, or were there only a primary circuit? [closed]

In a typical modern nuclear plant, there are : a primary circuit, which allows to transfert the heat of the fission (transfered to the water) to a secondary circuit. a secondary circuit, which ...
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Why is the French Wikipedia of Tchernobyl plant stating the the power is of 1000 MW while English version states that this is 3200 MW?

The power of a given reactor for the Tchernobyl plant is, according to Wikipedia : 3200 MW (12800 /4 reactors) Reference : https://en.wikipedia.org/wiki/Chernobyl_Nuclear_Power_Plant "Reactors ...
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How do I reduce proton number of an atomic nucleus?

I know that one can increase proton number of an atomic nucleus by proton bombardment as Cockroft and Walton bombarded elements with protons and managed to increase the atomic number. However, how can ...
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The units of unified atomic mass

There is something I don't understand about the units of unified atomic mass. I have seen on Khan Academy that $1$ unified atomic mass ($u$) is equal to $1.6605\times 10^{-27}$ kg. But after 2 videos ...
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Predicting the mass of hydrogen

After spinning around the atomic mass equation for calculating neutron separation energies, I have run into somewhat of a conundrum. It appears that the mass of the simplest of the examples, hydrogen ...
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Mass difference due to electrical potential energy

The masses of protons and neutrons are different. Suppose a proton is a sphere with a uniformly positive charge distribution. Can the mass difference between protons and neutrons be due to the ...
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Why is mass defect calculated by the rest mass (energy)?

I'm a high school student, and I have a question about the mass defect. I learned that when nuclear reaction occurs, the total rest mass (or rest energy) of reactants is greater than that of products, ...
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Nuclide Chart: cross-section for unstable isotopes

Why is there no cross-section for neutron capture on a nuclide chart for unstable isotopes (e.g. beta-plus/minus decaying isotopes). Since there are half-lifes long enough to make measuring those ...
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In Al27 (alpha,n): why is a neutron ejected?

Why does a neutron get ejected when Aluminium-27 is hit with an alpha particle? It seems like: Al-27 + He-4 --> P-31 (stable) and a gamma/(s) as the nucleus re-arranges. So why eject the neutron ...
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What is the origin of radioactivity that appears *sometimes* in rivers close to a nuclear plant? [closed]

What is the origin of radioactivity that appears sometimes in rivers close to a nuclear plant? (due to nuclear plant activity) ? In particular, is it due to primary circuit that would contaminate the ...
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What substance is being sprayed during this scene in Chernobyl?

In HBO's Chernobyl series, after reactor no. 4's meltdown, soldiers (Chernobyl's liquidators) splash a light-brown liquid onto the ground, both streets and forest, and for washing vehicles; for this ...
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Can alpha, beta or gamma particles induce fission?

Nuclear weapons and reactors get their chain reactions underway via neutron radiation, but do other radiation particles ever contribute?
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Why is uranium's atomic weight listed as 238.02891, higher than almost all known isotopes?

The vast majority of uranium is U-238, and most of the rest is U-235, U-232, U-234, etc.... So how can the averaged atomic weight be a little over 238?
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Can the ratio of gravitational force to Coulomb repulsion force in the nucleus be increased by adding neutrons? How many?

As you know, the ratio of gravitational force to Coulomb repulsion force between two protons is very small. This means that the source of nuclear stability cannot be the force of gravity. Can some ...
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Why least active metals have highest conductivity

Metals like copper, gold,silver hold the lowest spot in chemical reactivity series ie; they show more tendency to get reduced than any other metal; but in terms of electrical conductivity they hold ...
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Velocities of different quark types inside nuclei

Using the uncertainty relation \begin{equation} \Delta x \Delta p \geq \frac{\hbar}{2} \end{equation} we can calculate the momentum uncertainty on a length scale of a nuclei. Assuming $r_{nucleus} \...
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Pressure stabilisation of radionuclei

Looking at explanations of neutron stars, the neutrons towards the center of the star are stabilised by the enormous pressure, and so don't undergo nuclear decay. I am wondering if this is possible ...
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Difference between bound and unbound nuclear states?

What are the differences between bound and unbound nuclear states? What does bound or unbound excited states mean? Please explain in nuclear sense.
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Wave function of a proton and a neutron with and without isospin

Suppose I have a proton and a neutron in an external harmonic oscillator potential well. Let us first neglect all interactions between the two: since they are distinguishable particles I conclude ...
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Where does the proton's kinetic energy go when a proton and nuclei are fused together to create a heavy nucleus? I cannot solve this problem

The problem then states: estimate the minimum wavelength of the gamma ray photon. The answer to this question is: 0.25 x 10^-11 - (binding energy of oxygen - the binding energy of F which is 0.04 x 10^...
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Is mass gained from the fusing of two nuclei with nucleon numbers higher than 56?

I am just confusing myself with binding energy and the binding energy curve. I want to know whether I have interpreted the graph right. So when both nuclei have a nucleon number over 56 and are fused ...
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Why is the mean density the same for all nuclei? Tell me if this is a correct theory?

So the radius $R$ of the nucleus is directly proportional to $A^{1/3}$ (the nucleon number). As $$V = \frac 43 \pi r^3,$$ this makes $V$ directly proportional to $R^2$. Also, as the nucleon number ...
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What is the explanation for the elevated levels of iodine-131 near Vermont shown in this video?

At 9:07 in the latest Veritasium video, we see a map showing elevated levels of iodine-131 in the United States. The big band through the mid-west makes perfect sense to me; nuclear weapons tests ...
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What does the prime symbol indicate in a nuclear reaction?

I've come across a reaction shown as $ ^7\text{Li}(\alpha,\alpha^\prime)^7\text{Li}^*$. I understand that the asterisk indicates that the final $ ^7\text{Li}$ is in an excited state, but what about ...
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Would neutron moderator anisotropy improve nuclear reactor performance?

Nuclear fission reactors require the presence of a neutron moderator in order to sustain a chain reaction, as it slows down neutrons sufficiently in order for them to be absorbed by fuel (e.g. U-235) ...
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How did scientists come to know what to do with $E=mc^2$? [closed]

When Albert Einstein proposed his famous equation $E=mc^2$ for rest mass he never said anything it's about about breaking the nucleus. Then how did scientists come to know what this mean? But again ...
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What is 68A MeV for a xyz reaction?

I am reading a research paper and to explain an experimental data, the author has written.... The 68A MeV Li + p scattering data are reanalysed..... I understand that A = atomic mass but how do I read ...
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Why does nuclear fusion not occur with nuclei with a nucleon number higher than 56? Please tell me if I am correct

Please tell me if my assumption is correct. So nuclear fusion does not occur with nuclei (with a nucleon number higher than 56) because the binding energy of the product nucleus is lower than the ...
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What is thermal capacity in a nuclear power plant?

I am looking at a nuclear powerplant reactor that has 3.2GW "thermal capacity" and 1GW "nameplate capacity". What does the thermal capacity entail? Is it how much heat the reactor ...
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What is the difference between ion beam and laser?

What is the difference between laser beams and ion beams, especially in inertial confinement fusion? In inertial fusion, we use lasers as well as ion beams for driving the reaction. What is the ...
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Would an atomic bomb detonate a uranium stockpile? [closed]

If a uranium atomic bomb directly hit a stockpile of weapons grade uranium, would the chain reaction also detonate the stockpile? what about a stockpile of nuclear reactor fuel rods? what about a ...
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Why is hydrogen-boron called a fusion reaction?

As we know, we usually call fusion such a reaction in which two light nuclei make a heavier one and release energy. For fission, a heavy nucleus breaks into light ones. My question is, in proton-boron ...
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Peaks in Co-60 gamma spectrum

The following plot shows data collected from a Co-60 coincidence experiment. The detectors used were NaI(T) scintillation detectors. One detector was gated around the 1.33 MeV peak and the second ...
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In neutrinoless double beta decay, what happens when the neutrino(s) is/are absorbed? Is a lepton released, as per usual?

Neutrinos are detected when they 'hit' a nucleus and are re-directed (z-boson) or 'create' a leptons that matches the type of neutrino.... What happens when the neutrino(s) in a neutrinoless double ...
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Can Uranium-235 absorb neutrons and become U-238 instead of splitting?

Does that happen, on occasion? Does anyone know? I suppose it is quite rare, ... To absorb three neutrons without once fissioning... Could U-235 absorb three neutrons at once? Or just one, becoming ...
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Is it true that *free* nucleons don't interact with each other while they do in matter (nucleus, nuclear matter, neutron stars, etc.)

In the context of nuclear physics, a physicist wrote in a non large audience document (not available on the web nor in books) that the free nucleons don't interact with each other while they do in ...

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