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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88 views

Did the Chernobyl power station's water cistern really hold $7000\:\rm m^3$? [closed]

In he HBO TV miniseries Chernobyl, they talk about a cistern holding 7000 cubic meters of water. That is the content of Loch Ness, the deepest lake in the UK. Would the Chernobyl reactor really hold ...
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Why neutrons production is falling along beam axis in proton/nucleus collisions?

I'm studying a case where I simulate a protons beam (~70 MeV) on a spherical target composed of light nuclei such as carbon and oxygen. I'm looking for the angular distribution of neutrons produced by ...
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1answer
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Why is the graphite moderator in a nuclear reactor radioactive?

Some nuclear reactors (like the RBMK in Chernobyl) use graphite as a neutron moderator. As far as I understand, this graphite material, either in rods or as blocks with embedded channels, surrounds ...
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232 views

Why does steam in Chernobyl reactors speed up nuclear reaction?

After watching the TV series Chernobyl I am struggling to understand why steam in a reactor core would increase the rate of the nuclear reaction. My first guess would be that liquid water would ...
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49 views

How to determine which force mediates an interaction?

I have been given an assignement gives me a number of interactions, asks me to determine which, among these interactions are permitted under conservation laws (Charge, Baryon number, Leptonic numbers, ...
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3answers
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How do nuclear properties influence the atomic properties and vice versa?

I was wondering how the nucleus can influence the atomic properties (chemical and physical). I found that the mass number influences the boiling, melting and density of an atom. Also the electron wave ...
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2answers
94 views

How can Sun burn in space?

If there is no oxygen in space how can sun burn in space. (even though I know fire is caused by nuclear reaction inside sun)
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How does an ordinary object become radioactive?

In the 2019 miniseries "Chernobyl", ordinary objects are depicted as being capable of becoming radioactive, such as clothes, water, stones. How exactly does something composed of a non-radioactive ...
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64 views

How does the Earth remain in its shape?

I know only stars do nuclear fusion to keeps its shape from gravity. Then what about the Earth? Earth doesn't do nuclear fusion. How does the Earth keep its shape even though the gravity keeps pushing ...
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32 views

Why do we think of a nucleus as nucleons held together by a strong force rather than a cluster of quarks? [duplicate]

The implication of this point of view is that protons and neutrons retain their structure in a nucleus. That is the 3 quarks making up nucleons still closely interact and interactions with quarks from ...
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What if a fusion reactor had moving parts?

I have never dug into fusion physics, but from what I gather one of the main problems is confining the fusion in a small region of space for long enough to get enough helium fused to counterbalance ...
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379 views

Whats the next step after commercial fusion reactors? [closed]

I'm trying to write some science fiction where they've had nuclear fusion working for quite sometime, interplanetary travel is no problem, and they're debating making the next step to a radical new, ...
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Released energy during fusion reaction

Click to view the video at required time According to the video in the link above the binding energy for deuterium is about 2 MeV and the binding energy for tritium is about 8 MeV so the total for ...
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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+...
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1answer
45 views

Possible spins and parities of $^{38}_{17}Cl$

In my introductory nuclear physics course, the following question came up: Consider the odd-odd nucleus $^{38}_{17}Cl$, which has 17 protons and 21 neutrons. Its 17th proton sits in the $1d_{3/2}$ ...
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3answers
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Could the plume from an exploded nuclear reactor corrode helicopter blades?

I was recently watching the new TV series Chernobyl and was curious if something that occurred was even physically possible. In the show, the physicist instructs the pilots of a helicopter not to fly ...
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Why are lighter nuclei dominated by $\beta$-decay and heavier ones by $\alpha$-decay?

While I'm trying to understand the nature of radioactive decay, I found that the lighter nuclei mostly have $\beta$-decay while heavier nuclei have $\alpha$-decay. From what I know is that the $\...
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22 views

Nuclear isomers with a long lifetime

A lot of nuclear isomers with long half-lives have N and Z numbers in a range from 39-49 or 69-81. What is the reason for this? Is it possible to explain this with the nuclear shell model?
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58 views

Why can radon be held in your hand without harm but if it's inhaled it very dangerous?

Why can radon be held in your hand without harm but if it's inhaled it very dangerous? I was thinking that because radon emits alpha particles they wouldn't penetrate your hand? but if they were ...
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1answer
67 views

How is the spin of the odd-odd nucleus 6Li explained? [duplicate]

Spins of odd-odd nuclei is difficult to predict. But $^{6}Li$ is light - only 6 nucleons. $^{6}Li$ should have spin $(\frac{3}{2} + \frac{3}{2}) = 3$ by shell model, as should have one proton on $p_{...
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Yukawa force vs Nuclear force

I have read these questions: Are Neutrons and anti-Neutrons attracted to each other over distance? Where John Rennie says: Neutrons and anti-neutrons repel each other with a Yukawa force ...
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1answer
34 views

(What causes) the *other* Compton edge?

The question If one exposes a scintillator to a gamma source, one will observe two features for each characteristic energy in the source: a photopeak, due to complete absorption of photons, and a ...
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3answers
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Binding energy, fission and fusion

My high school physics book doesn't elaborate the idea of binding energy and how it's related to fission and fusion adequately in a way that made me have wrong thoughts about these ideas. What i ...
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1answer
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Radioactive material

If a small sample of radioactive material is brought closer to Geiger counter. It detects alpha, beta and gamma radiations from the sample material. can someone tell me how the alpha radiation from ...
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5answers
61 views

Harm from gamma radiation compared to beta radiation

why is a small dose of gamma radiation less harmful than a small dose of beta radiation? even though gamma radiation is more penetrating. This is a question I was wanting to know and had difficulty ...
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Does pair production happen even when the photon is around a neutron?

In order for a photon to decay into a pair of $e^+ e^-$, it must have at least $E_{\gamma}=1.022$ MeV and must be near a nucleus in order to satisfy the conservation of energy-momentum. But would ...
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1answer
66 views

Branching ratios for alpha decay into a rotational band

I want to understand the $\alpha$-decay of $242$-Curium to different excited states of $238$-Plutonium (image taken from Introduction to Nuclear Physics page 258; Author: Krane): I'm interested in ...
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49 views

Conservation of lepton

I was reading a bit about nuclear/particle physics when I came up to Cours et problèmes corrigés de physique nucléaire et de physique des particules by Philippe Miné in 2016 ISBN 2340011566, which is ...
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1answer
40 views

Fission fragments

I was reading a bit about nuclear/particle physics when I came up to Cours et problèmes corrigés de physique nucléaire et de physique des particules by Philippe Miné in 2016 ISBN 2340011566, which is ...
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2answers
108 views

If a country wants to build nuclear weapons, why would they enrich uranium instead of turning uranium to plutonium? [closed]

Firstly, I have to say that I'm bad at physics. So, please correct me if I say something wrong. I have read that natural uranium contains 99.28% of U-238 and only 0.72% of U-235 which is the ...
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Binding energy and strong force

If binding energy is responsible for holding nucleons together than what is meaning of strong force?
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57 views

What causes the β-decay in Uranium-239 and Neptunium-239?

When a neutron is added to the nucleus of Uranium-238, it becomes Uranium-239. Now, the Uranium-239 undergoes a β-decay and becomes Neptunium-239. This Neptunium-239 again undergoes another β-decay ...
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1answer
41 views

What is the sd-shell in the nuclear shell model?

I understand that the energy levels in the nuclear shell model go as: $$1S_{1/2}, 1P_{3/2}, 1P_{1/2}, 1D_{5/2}, 2S_{1/2}, 1D_{3/2}$$ But what is meant by the "sd-shell"? Is it something to do with ...
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1answer
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How do the probabilities in decay schemes work? (Ir-192)

I'm incredibly confused as to how the probabilities work in decay schemes (Particularly for Iridium-192). There are the green numbers to the left of the image that appear to add up to the total ...
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1answer
23 views

How can I find the nuclear interaction length in solid lead given atomic number, radius of the lead nucleus and lead density?

I need to estimate the nuclear interaction length in solid lead given the atomic mass unit $A=207.2u$, radius of lead nucleus $R=r_0A^{1/3}$ where $r_0=1.25fm$ and the density of lead is $\rho=11.34g/...
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1answer
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Help in identifying an instrument used in nuclear physics

In American-British drama miniseries Chernobyl, on the second episode, a scientist takes some dust from the outer surface of a window and places it in an instrument that tells her what radioactive ...
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Could the pressure from the steam explosion in Chernobyl (if it occured) have made the corium critical?

As other questions (eg How large would the steam explosion at Chernobyl have been?) regarding that episode 2 of the Chernobyl series, the megaton estimate of the steam explosion looked very improbable ...
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26 views

Should the mass of the electron be included in the mass of products when calculating mass defect?

In a physics question, I encountered a beta minus decay reaction. If I were to calculate the mass defect, should the mass of the electron be included in the mass of the products?
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Reaction energy $Q$

Really simple question, but I'm confused with it because of contradictions between sources (absence of clarity online vs lecture notes (says nuclear) and practise questions provided (uses atomic) ) ...
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Risk of megaton steam explosion from Chernobyl? [duplicate]

In the new Chernobyl TV series (https://en.wikipedia.org/wiki/Chernobyl_(miniseries)), in episode 2, there's a reference to the risk of a steam explosion from the molten reactor core entering a water ...
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How large would the steam explosion at Chernobyl have been?

So the second episode of the HBO series began to cover the risk of a steam explosion that led to them sending three divers into the water below the reactor to drain the tanks. This occurred after the ...
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Finding the time scale of captures rates

I'm trying to calculate some capture rates. The dimension of $\Gamma$ in the paper that i'm following is $MeV^4$ which is weird to me since I expected it to be MeV =$time^{-1}$. Also, the balance ...
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Is there any evidence that the protons repel each other? [closed]

Please let me know if there are experiments or data that show it
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Explain to me why the following reaction can happen in big stars but not on earth

$$ \rm {}^{12}C +{}^{12}C\rightarrow {}^{20}Ne + {}^4He $$ why doesn't this reaction occur on earth? but occurs in big stars?
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What change happens inside a molybdenum nucleus? [closed]

What happens/takes place in the molybdenum nucleus as it decays to Technetium-99 when a beta particle is emitted?
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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 ...
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Are fundamental particles more than their properties?

Parent questions: What came first, neutrons or electrons? Why saying that during electron capture the electron is converted to a neutrino? Background: various nuclear phenomena show the ...
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Binding energy - why is my logic wrong?

We have some protons and neutrons and want to create a nucleus. We must do work against the Coloumb force to bring these protons and neutrons together to form the nucleus, this increases the energy ...
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Why are statistical approaches used in Physics?

Statistical analysis is the analysis of a very large number of particles / sample space where the general behaviour and trends of these particles is studied. But this also means that its probabilistic....