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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9
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3answers
135 views

Could the end cap of the Pascal B (1) survive its trip through the atmosphere?

In 1957, the US had a nuclear test where a shaft was dug 152 meters into the ground. A 100 mm thick, 900 kg steel plug was installed and welded at the top of the shaft. Under it was 2 feet of ...
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5answers
247 views

How can beta plus decay be possible?

$\beta +$ decay is where a proton gets turned into a neutron and a positron and a neutrino. However, a neutron is heavier than a proton, so obviously this reaction is endothermic. So then, why does ...
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1answer
44 views

Nuclear Physics Question

How could I calculate the chance of a proton actually joining the nucleus and 2 protons and 3 and so on? Assuming a large number of protons are fired at a substance?
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2answers
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Baryon number conservation

Can someone explain me why the Hamiltonian for the nucleon field (derived from the corresponding Lagrangian) $$H_N=\int d^3xN^\dagger(\textbf{x})\Big(-\frac{\nabla^2}{2M_0}+M_0\Big)N(\textbf{x})$$ ...
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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
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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 ...
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0answers
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Understanding the Level scheme of a nucleus from Nuclear Data Base

Sorry If this Question is not eligible to be posted here. Nuclear database shows observed nuclear electronic energy levels of $O^{17}$ having neutron separation energy 4143 keV. I want to find ...
8
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4answers
2k views

Does a proton have a binding energy?

When calculating the $Q$-value, $Q = \Delta M \cdot c^2$, of this reaction: $$ ^6Li \ (\alpha, p)\ ^9Be \quad \iff \quad \alpha + \ ^6Li \ \longrightarrow \ ^9Be + p $$ The $Q$-value can also be ...
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Shell model label symmetry

I'm working through the quark model Hadron wavefunctions, and trying to figure out the flavour-spin part of the wave functions. This is easy enough for S shell spatial states, since the space wave ...
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1answer
95 views

Is this a radioactive meteorite? [closed]

Can a neutron beam emission from a strong naturally-occurring radioisotope deflect a small sewing needle hung by a thread an inch from the source? I have someone reporting to me of such a thing ...
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1answer
80 views

Trinity vs Nagasaki

From what I read the radiation levels in Nagasaki today are equivalent to the natural background radiation levels in the surrounding areas. On the other hand, the radiation levels at the Trinity test ...
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1answer
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Shell Model of the Nucleus Holes

Can someone help me how to determine whether there is a hole or a particle in a given shell? Is it as simple as if the number of particles is close to the number of the maximum particles in each shell,...
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1answer
23 views

Why doesn't a deuterium-deuterium reaction usually yield Helium-4?

I assume the above reaction is less energetically favorable than the creation of He-3 (plus a neutron) or tritium plus a proton? But why/how? Or are the hard, hot, fast collisions too much for it to ...
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0answers
188 views

How exactly did lowering of the graphite parts of the control rods on Chernobyl's RBMK reactor result in reactivity surge?

There are many sources giving different data on the initial position and the dimensions of the rods, but most suggest that the absorber was located just outside the core when AZ-5 was pressed, and the ...
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1answer
45 views

How does the strong interaction “create” the nuclear force?

I’ve recently read that the strong interaction, that holds the quarks together to form protons and neutrons, also creates a residual force called the nuclear force, which holds the neutrons and ...
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1answer
50 views

Direction of neutron scattering

When neutrons interact with matter scattering, what direction to they scatter? Is it random, or some probability distribution of directions? I'm trying to understand why neutron reflectors reflect ...
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1answer
83 views

Why does fusion above nickel 56 require energy?

I've always struggled with the concept of fission and fusion. I mean I can show a mass deficit with math easily enough but I have always struggled understanding the fundamental concept of why things ...
0
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1answer
44 views

How does heat is generated during nuclear reaction

In a nuclear reaction 235-U is being constantly divided under high neutron flux. After the division we get 2-3 neutrons with high energy and fission products with its own energy. My question is from ...
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6answers
7k views

Is fission/fusion to iron the most efficient way to convert mass to energy?

Is fission/fusion of any element to iron-56 (or nickel-62?) the best way to convert mass to energy, that doesn't involve black holes? In other words, will we be always limited to convert only about 1%...
2
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1answer
89 views

Irradiated persons as sources of radiation?

The new HBO series "Chernobyl" is supposedly filled with misconceptions about radioactivity, among other things, according to an opinion piece published in "Forbes". In particular: "The most ...
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2answers
103 views

Why don't we coat the pressure vessels of nuclear reactors in boron to reduce neutron embrittlement?

Neutron embrittlement is a big problem in reactor design, as high energy neutrons cause lattice defects in materials like steel by slamming into iron nuclei. This limits the lifetime of the reactor, ...
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1answer
1k views

What was the vertical beam of light in Chernobyl?

In the HBO miniseries Chernobyl after the initial explosion we see a clear bright light shooting vertically up from the plant. I presume this was a thing that actually happened and not some creative ...
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1answer
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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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1answer
23 views

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 ...
13
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1answer
6k views

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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2answers
253 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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0answers
50 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
66 views

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
100 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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5answers
12k views

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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2answers
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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0answers
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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1answer
49 views
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1answer
62 views

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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3answers
383 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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0answers
33 views

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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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+...
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1answer
49 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
95 views

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 ...
3
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1answer
55 views

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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0answers
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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1answer
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
69 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_{...
4
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3answers
108 views

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
35 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
53 views

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
32 views

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 ...
3
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5answers
64 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 ...
13
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3answers
937 views

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 ...