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 is it impossible for the reactor of the nuclear power plant to turn into an explosive nuclear bomb?

Is it true that both work on the same principle of operation: the interactive fission chain reaction 235U/239Pu and the bombardment of uranium-235 by fast neutrons produce a fission chain reaction ...
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1 answer
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How many more neutrons are flying around in a fast reactor vs thermal reactor?

I'm a bit confused on the number of neutrons in a fast reactor. So the average neutron in a thermal reactor is 0.05ev and 700kev in a fast reactor. This means fast reactor neutrons are travelling sqrt(...
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Alpha particle moving faster than the speed of light

In this problem I was solving a beam of uniform cross section carrying a current of $0.25\ \mu A$ by alpha particles. The mass of an alpha particle is $m_\alpha=4m_p$, where $m_p$ is the mass of a ...
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2 answers
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Model of a neutron composed of a proton and an electron

Is it possible to establish a model to describe neutrons as electrons and protons bound by the coulomb force? what disadvantages would it have?
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1 answer
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How Chadwick concluded that the particles are neutrons but not photons?

James Chadwick conducted an experiment in which he bombarded Beryllium with alpha particles from the natural radioactive decay of Polonium. How he concluded that the radiation was made up of neutrons ...
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Why parity conserves in fermi transition?

Beta decay is a weak interaction process and in weak interaction parity doesnot conserve , then why in fermi transition initial and final parties of the nucleus is conserved ?
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What exactly is energy self-shielding in nuclear physics?

I have recently been trying to understand self-shielding, both energy and spatial self-shielding. I am having a particularly hard time understanding energy self shielding. Thus far, everything I’ve ...
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Cause of energy release in fusion [duplicate]

For the fast few months, I have been scratching my head for this problem which I have faced while studying fusion. In a hydrogen fusion, two hydrogen (for instance ) fuse to form a helium nucleus. I ...
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1 vote
2 answers
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Why lead plate was used in Rutherford's gold foil experiment?

I have read that lead plate is used to concentrate the beam of alpha particles which are being directed towards the gold foil as it is a heavy metal. But there are other heavy metals like manganese, ...
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1 vote
0 answers
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How was Potassium used to estimate the effect of backgrounds in the Homestake experiment?

I'm trying to understand some of the details of the Homestake experiment, which attempted to measure the rate of neutrino production by the sun. In particular, I'm interested in how Davis et. al. ...
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Can fissile fuel be used in a conventional space rocket

Is there anyway to incorporate fissile fuel into rocket propulsion other than using it to heat the fuel? What if you dissolve the fissile material into molten salt, and then inject it into the ...
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75 votes
2 answers
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Why doesn't a nucleus-like body made up of just neutrons exist?

We know that neutrons exert short ranged nuclear forces over other nucleons in a nucleus, and these forces are only attractive in nature. Also this force is universal and doesn't differentiate between ...
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4 answers
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Why is some mass converted into energy when neutrons and protons combine to form nucleus?

So some of the mass is converted into energy when neutrons and protons combine to form nucleus. Why? And how? And then why do we need to supply the same amount of energy to separate them?
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2 answers
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Nuclear fusion mass defect and energy production

In researching the topic of nuclear fusion, I have a few doubts related to the mass defect, 'negative' potential energy and resultant energy released as a by-product of nuclear fusion. When two ...
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10 votes
2 answers
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Why were sparks created in Rutherford's alpha particle scattering experiment?

So I just read that when alpha particle hit the gold foil sparks were created. And these flashes were used to determine the angle of scattering. So were the sparks created because the alpha particles (...
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1 answer
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Bateman equations result for U235 with & without MOX

I would like to get the values of the Bateman equations result of the following picture : This picture comes from the following page : https://www.radiation-dosimetry.org/fr/quest-ce-que-lequation-de-...
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-1 votes
5 answers
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Can fission and fusion happen together? [closed]

Like making up them together first splitting in the term of fission then adding them up.
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1 vote
0 answers
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Why aren't electrons accounted for when calculating the energy of nuclear decay? [duplicate]

In my physics exercises, I had to calculate the energy generated by the decay of an atom of the isotope 40 of K by Beta - decay. It gives us the products: isotope 40 of Calcium and one electron. When ...
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11 votes
3 answers
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Can Jupiter turn into a star if it radiated off enough heat?

Since a star heats up when it radiates more heat (via gravitational compression), and since that's also how protostars turn into stars, I was wondering what are the chances of Jupiter reaching the ...
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Isotope stability in alkali vs alkaline earth metals

Why do alkaline earth metal atoms (and those with similar atomic structure, like Yb and Cd) have more stable isotopes than alkali metal atoms?
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11 votes
3 answers
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What happens when the universe runs out of fuel?

After some X billion years, one would think the stars in the entire universe will run out of hydrogen. What would happen next? Is there any way to get hydrogen out of heavy metals (extreme fission)? ...
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2 votes
2 answers
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Why are fermionic atoms less prevalent than bosonic ones?

Many atoms have no stable fermionic isotopes. Those that do typically have more stable bosonic isotopes than fermionic ones. Furthermore, the fermionic isotopes of most atoms are lower in natural ...
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The nuclear spins of alkali metals

Looking at the different isotopes of alkali metals and their nuclear spins, I notice that nearly all of their bosonic isotopes have nuclear spin of 3/2. Surely there must be an explanation in nuclear ...
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3 votes
2 answers
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Why do elements, as they have more protons, need a higher amount of neutrons to stabilise them? [duplicate]

I've seen the graphs of the stability line but I can't find any reason as to why this happens, I understand radiation, just not why radiation needs to occur in the first place if that makes sense.
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1 answer
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Is there a way to calculate the blast radius of an explosion starting with the yield of the bomb? [closed]

I am working on a video game with missile-oriented combat, and I would like to input a yield for a missile instead of directly giving it a blast radius, and have the program calculate the blast radius ...
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2 answers
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Heating Plasma in Inertial confinement fusion

How is the plasma heated in ICF? I know in MCF in the ITER tokamak uses external methods such as NBI but how in inertial confinement fusion is the plasma heated to the temperatures which allows ...
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0 answers
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What is (alpha, xn) reaction?

Is (alpha, xn) a reaction where an alpha reacts with a nucleus and multiple neutrons are released? Or does x stand for X-ray? It seems more likely but shouldn't it be gamma ray instead? Are gamma rays ...
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Fusion energy origin

In fusion , I have understood so far that two light nuclei fuse to form a heavy nucleus. The nucleons in the light nuclei experience lesser binding energy as compared to the nucleons in heavy nucleus ...
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1 answer
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Unexpected distingration energy value during alpha decay equation [closed]

I am trying to solve the disintgration value of the below decay equation but the issue I am having is my result seems way to high compared to what is expected (around 5-6 MeV). $$^{213}At \rightarrow ...
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-4 votes
1 answer
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Confused by coefficients that don't list their units

Let's suppose we calculate the energy released by the decay/fission of 1 kilogram of plutonium-239. Can we find the energy released in one kilogram of decay? Wikipedia says there's $3.318*\times10^{-...
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1 answer
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Coriolis effect on the nucleus?

Would there be a coriolis effect on the (surface) of the nucleus? Since the nucleus can be approximated as a 'liquid drop' which rotates.
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1 answer
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Deriving isospin factors in phenomenological pion nucleon nucleon interactions

Preface One commonly finds this interaction Lagrangian in phenomenology (ignoring constants): $$\mathscr{L} \propto \bar\psi \gamma^5\gamma^\mu \vec\tau\psi \cdot \partial_\mu \vec\pi \tag{1}$$ ...
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Why does the stability of a nucleus depend on the binding energy $\textit{per nucleon}$ instead of the total binding energy?

The larger the total binding energy of a nucleus, the greater the minimum energy that must be added to infinitely separate the constituent nucleons. Shouldn't the total binding energy, then, be used ...
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1 answer
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Probabilities of the different fission reactions in U-235

I have found out that the 3 main fission reactions in U-235 are given as: U-235 + n ===> Ba-144 + Kr-90 + 2n + Q (about 200 MeV) U-235 + n ===> Ba-141 + Kr-92 + 3n + Q (170 MeV) U-235 + n ===>...
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1 vote
1 answer
27 views

Minimum energy of projectile to trigger a nuclear reaction and energy of ejectiles

I am studying the following type of nuclear reactions : projectile+target -> ejectile1+ejectile2 I make the assumption that the target is static. This reaction needs energy to be triggered (Q-value&...
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0 answers
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How can a proton in a nucleus decay into neutron and positron in β+ decay if neutrons have greater mass than a proton? [duplicate]

I'm guessing it has something to do with mass defect/binding energy??
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2 answers
80 views

Why is the Fermi Radius not equal to proton radius?

I teach IB physics and recently attempted explain to a student where the Fermi Radius formula comes from in response to a question. For those unaware the fermi radius formula is shown below. $$ R = ...
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0 votes
4 answers
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How much faster does induced fission in a typical reactor occur than spontaneous fission in nature?

I know that the half-life of Uranium-235 is about 704 million years, but... That includes alpha and beta radiation as well as spontaneous fission, though... Also, I presume the 'spontaneous fission' ...
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0 votes
1 answer
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Where can I find photon absorption cross-sections for various isotopes?

I am looking for absorption cross-sections for photons. Usually, I am dealing with neutron absorption where I utilize https://www.nndc.bnl.gov/endf/ for my data. This is a really handy website that ...
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0 answers
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$Q$-value definition checking

Consider a nuclear reaction being going on which is $$A +B -> C + D ,$$ is it true that $Q$-values which is defined to be difference in the masses energy from reactants to products. Will give us ...
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1 vote
1 answer
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Why can't spherical nuclei rotate?

When studying nuclei it is said that spherical nuclei do not rotate, instead rotations are considered for deformed nuclei only. I do not understand why is that. If one can write the hamiltonian of ...
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23 votes
7 answers
3k views

Is special relativity relevant to understand nuclear bombs?

It is often claimed that Special Relativity had a huge impact on humanity because its understand enabled the invention of the nuclear bomb. Often, the formula $E = mc^2$ is displayed in this context, ...
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How are Inertial Confinement Fusion reactors and Hypersonic Projectile fusion reactors going to generate continuous energy?

Perhaps I have not investigated enough, but all the recent (and older) news articles about the Ignition Facility in northern California and the First Light reactor in the UK fail to state how they are ...
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-1 votes
1 answer
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Why is it when an atom gains a proton it is said to become an 'atom' of a different element?

My confusion lies in that the number of protons in the nucleus will increase but is the number of electrons assumed to automatically follow suit such that the result is a neutral atom with equal ...
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Understanding a Gsponer formula about mi

I'm reading over one of Andre Gsponer's papers on nuclear weapons. I'm confused by section 3.2, particularly formulas 3 and 4. (3) states: $$ \eta_\mathrm{fission} = \frac{\rho R - \omega_c}{\rho R} $$...
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1 vote
2 answers
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Does a part of the difference in mass-energy excite the nucleus to a higher energy state during beta decay?

According to this site: https://byjus.com/physics/radioactivity-gamma-decay/ Most of the time, gamma decay occurs after the radioactive nuclei have undergone an alpha or a beta decay. The alpha and ...
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1 answer
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How will "Fusion Power" deal with it's waste heat?

in application of Fusion power, even if it were doable at present, given the multi-million degree operation, how does such a system dispose of waste heat if plasma is magnetically confined?
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1 answer
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What is the value of the SPIN magnetic moment of a proton?

If I understand it correctly the anomalously large total magnetic moment of the proton inside the nucleus of the atom is because it is a combinatoric particle and there are contributions by the quarks'...
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2 answers
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Can I hit a high energy neutrino beam onto a water container with no damage?

I read at Super Kamiokande water is surrounded by many photomultiplers to detect neutrino interactions. I was wondering if water was stored into some container and yes then can I shoot a neutrio beam ...
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2 votes
2 answers
165 views

If plutonium-238 (Pu-238) absorbs a neutron, does it become Pu-239?

I am asking this simple question because I am always hearing about how thorium reactors are less perilous to the world because, unlike uranium reactors, they produce some Pu-238, which is not suitable ...
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