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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1answer
105 views

How many times do solar protons repeatedly fuse and fission before they form deuteron

In the proton-proton chain reaction in the Sun, the first step is $$p + p \rightarrow \; ^2_2{\rm He} .$$ After this, the most likely thing to happen next is that the reverse reaction occurs: the $^...
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If the probability that an alpha will deflect is $1/10000$, for $n$ layers, is the probability is only $1/10000n$?

I have attached a picture of an extract I read on Wikipedia (also in the AQA A-Level Physics specification and textbook). It says that 1/10000 alpha particles deflected in the alpha particle ...
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How to derive the allowed beta decay selection rule $\Delta L=0$?

Starting from the beta decay matrix element and Fermi's golden rule how can one show that the matrix element at the leading order vanishes unless $\Delta L=0$?
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1answer
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Why Don't All Heavy Elements Decay into $^{62}\rm Ni$?

I read the question If we assume that protons don't decay, then will all matter ultimately decay into Iron-56 or into nickel-62?, but I have a different question concerning the decay that has ...
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70 views

What are physical obstacles for rare earth metal synthesis in nuclear reactors in industrial scale? [closed]

Diminishing availability of rare earth metals prohibits expansion of traditional and quantum computing and low temperature technologies. So - my question is about artificial synthesis of rare earth ...
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Why the cycles completed by standing wave completed by electron in a certain orbit is same as principle quantum number?

According to the bohr model and de-broglie hypothesis why the cycles completed by standing wave completed by electron in a certain orbit is same as principle quantum number? When we derive the ...
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What is the Half-Life of a Large Chunk of Fissile Material?

Uranium-$235$ has a half-life of about $700$ million years and a critical mass of about $52\,$kg. That means if you take a large number of $U$-$235$ atoms, say a $26 \,$kg amount, and put each atom in ...
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49 views

What is the effect of isospin on the proton or neutron alone, i.e. not in a doublet?

So I start with a proton $p$. I extend my "physical" space by means of the internal degree of freedom of isospin, so that I know write $p$ in a higher dimensional space: $$ p = \left( \begin{array}{...
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2answers
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What if electrons were used in gold foil experiment?

I was studying Rutherford's gold foil experiment from my high school textbook. It states that ' by performing experiments in which fast electrons instead of alpha particles are projectiles that ...
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Elements Of the periodic table [duplicate]

Why even-numbered elements, with their even proton numbers are more abundant than odd-numbered elements ?
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11answers
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Why do fusion and fission both release energy?

I only have high school physics knowledge, but here is my understanding: Fusion: 2 atoms come together to form a new atom. This process releases the energy keeping them apart, and is very energetic. ...
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1answer
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Can an atomic nucleus contain both particles and antiparticles? [duplicate]

Is it theoretically possible to make a "deuterium" atom containing a proton and an antineutron in its nucleus? Would the strong nuclear force cause attraction between a proton and an antineutron? ...
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72 views

How to make uranium pellets produce heat? [closed]

Assume I have a uranium pellet as follows. What should I do to make it produce heat? And what is the physical condition of this pellet from which I know it must be replaced with the new one? Most ...
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Unit of pion-decay constant

In the natural unit system, the pion-decay constant $f_{\pi}$ is $92.4\:\rm MeV$. But I think that a decay constant should have a dimension of $[T]^{-1}$, where $[T]$ is the dimension of time. Then, ...
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How are composite hadron fields related to elementary quark fields?

(This question is related to: A pedagogical exposition of the hadron physics?) I'm a mathematician who has been trying to learn quantum field theory for a while. I've gone through large parts of ...
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Confusion about Unit Systems

I was reading about Deuterium and came to know that its binding energy is $2.22$ MeV. I am curious whether this energy is in the natural unit system where $\hbar = c =1$. For instance, the energy ...
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2answers
66 views

Nuclear Physics Brainstorm Question

I was wondering how it could be possible to artificially overcome the strong nuclear force, allowing for the nucleons to be released from each other. If you can't think of any possible solution, is ...
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1answer
86 views

Stability in Nuclear Shell Model

As far as I understand , a particular sub-shell is filled with either protons or neutrons, $2*(2l+1)$ number of them, and never both together since protons and neutrons fill up levels separately in ...
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1answer
140 views

Binding Energy and mass defect

Binding energy is the energy required to separate the nucleus into its constituent particles. The thing is that I read in a book that the binding energy is also the energy equal to the mass defect. ...
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1answer
21 views

Motivation behind the representation of differential cross sections using histograms

From my lecture notes: In most cases a cross section is represented in a differential way with respect to one or more observables. While it is possible to make a theoretical prediction for a ...
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213 views

Why does a star die once it has iron?

I found out that iron is the death element for stars, but I couldn't find why can anyone knowledgeable on stars explain why iron causes the star to die?
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1answer
166 views

Strong nuclear force vs electrostatic repulsion between protons

Does the strong nuclear force balance the electrostatic repulsions between the protons or does it overcome the repulsion? I looked up on wikipedia and it says that the strong nuclear force is ...
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1answer
34 views

Rate of reaction of collision in relation to the geometric cross-section

I am reading "Particles and nuclei : an introduction to the physical concepts / Bogdan Povh" and on page 44 of the book there is a section about the geometric cross section in a idealised scattering ...
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1answer
64 views

How is atomic position expressed in QM?

I am trying to understand how DFT works. I understand how to express the position of an atom or molecule in terms of the positions of the nuclei and electrons by setting up a Hamiltonian expressed in ...
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I have proved that radioactive disintegration is first order using probability. Is my proof correct? [closed]

I am a high school student and this is just a small attempt to prove why radioactive disintegration is first order. I don't even know if it has already been proved or not. Please let me know. I later ...
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4answers
247 views

Could an electron enter the nucleus, and if so would it be captured by a proton?

I've been trying to find an answer to this question, but have come across contradictory answers, and have limited knowledge of quantum mechanics myself. Almost all the threads (here and on Quora) ...
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Electronically controlled fusion reactor

It seems that currently, only two types of fusion reactor styles are being used for large scale testing: the Stellarator and the Tokamak. Both of these and a whole bunch of other designs have been ...
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Number of Isotopes created with decay <-> Chain Yield

The chain yield (or fission yield) states how many isotopes with a certain mass $A$ are created with the decay of $^{235}$U. But how do we know the fractions of specific Isotopes that are created ...
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1answer
61 views

Meaning of ft-values in nuclear physics

What is the "physical" meaning of the ft-value for a decay channel? From what I understand, the ft-value is inversely proportional to the square of the matrix element, hence I would expect a larger ft-...
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1answer
84 views

Determination of Dead time of a Geiger Muller counter using the two source method

While determining the dead time of a GM counter using the two source method, why do we ensure that only two sources are placed in the counter at all times i.e. while determining the counts when both ...
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156 views

How do you go about guessing the ground-state spin and parity of a nucleus?

How do you go about guessing the ground-state spin and parity of a nucleus? Questions of this form seem to be asked frequently here, e.g., for 19F, 23Na, and 87Rb and 40K.
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1answer
175 views

Why does Fluorine-19 have a nuclear spin of 1/2?

According to the nuclear shell model, $^{19}F$ has one unpaired proton in the $6$-fold degenerate $1d_{5/2}$ state, which means the orbital angular momentum is $l = 2$ and the total angular momentum ...
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Is this equation for mass defect correct? [duplicate]

I just want to know if this equation for the mass defect is correct $$\Delta m = Z * m_p + Z * m_e + N* m_n - A $$ where Z- Atomic number A- Mass number N- number of neutrons $m_p$- mass of the ...
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1answer
67 views

What drives the charge separation in atoms?

In atoms charges are neatly separated. Instead of pairing which seems natural they all stick together with their peers. What drives this peer behaviour? Why is it stable?
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How do electrons rearrange themselves after a fusion reaction?

The hydrogen atoms can fused inside Sun core into helium without considering about the free electrons, however what about special* cases where two neutrally charged hydrogen atoms collide and fused ...
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1answer
52 views

Derivation of nuclear spin $I$ for $^{87}$Rb and $^{40}$K

So I know that $^{87}$Rb has $I=3/2$, and has 37 protons and 50 neutrons. I try to make sense of it form the nuclear shell model: taken from here. 50 neutrons: they are a closed shell, so no net ...
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73 views

What new physics was discovered or needed as a result of the Manhattan Project? [closed]

I recently got into a discussion with colleagues regarding quantum mechanics and the Manhattan Project. My colleague (not a physicist) conjectured that it was mostly an engineering feat with little ...
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1answer
47 views

Average differential cross section of neutron scattering on diatomic molecules

I am using Born Approximation to calculate this problem and I've already got the solutions to both of the problems. What confused me is the definition of the unpolarized differential cross section: $$\...
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2answers
139 views

Lead catalyzed fusion

Consider the following setup: A beam of deuterons is accelerated towards a lead target. With sufficient acceleration (in the MeV range, nothing fancy...), I would expect some of the deuterons to fuse ...
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1answer
128 views

Do we know what causes the release of energy in nuclear fission?

I was trying to put together all the things I've read in the last couple of days and I realized that based on my current knowledge of the standard model and the way nuclear fission works, I'm not able ...
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1answer
32 views

How will the Big Rip affect chemistry and nuclear interactions?

The "Big Rip" is a theoretical scenario for the death of the universe. Let's assume that this scenario is true. What can we expect to happen to chemistry and nuclear interactions in the time ...
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formation of atomic nuclei from nucleons

What holds the nucleus together? In a nucleus there are several protons, all of which are positive. Why don't they push themselves apart? It turns out that in nuclei there are, in addition to ...
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Why does the chain yield in nuclear fission sum up to 200%?

The table of nuclides states the fission yield, or chain yield $Y$, the percentage of decays of $^{235}$U that lead to an isotope with mass number $A$. Why do they sum up to 200%? Wikipedia just ...
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6answers
129 views

Does the half-life of an element mean it will never decay completely?

Example: Half life of Polonium-194 is 0.7 seconds. If we supposedly take 50g of Polonium, there will surely be a time when no more of this Polonium will be left because if we consider the decay ...
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Woods-Saxon energy levels

I'm trying to calculate the bound state energy levels for a Woods-Saxon potential, given by: $$V(r) = -\frac{V_{0}}{1+\exp(\frac{r-R}{a})}$$ I'm using Numerov's matrix method, which led me to: $$H\...
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How could someone calculate the coulomb barrier transparency in 3 dimensions [duplicate]

Transparency is also called probability of transmission, or probability of quantum tunneling.
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What is the probability of fusion reaction happening with energy less than the coulomb barrier (probability of reacting nuclei quantum tunneling)?

$ E_{out} = 4 \pi n_1 n_2 (m_0-m_a) c^2{(\frac {m}{2k_B T})}^{3/2} \int_0^ \infty \sigma(v) v^2 e^{\frac {-mv^2}{2k_B T}} dv$ $m_0$ is the sum masses of the reacting nuclei, $m_a$ is the sum masses ...
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How does the nuclear interaction keep protons and neutrons together?

The strong force holds atoms hadrons together by using gluons to change the color charge of quarks and making the hadrons color nutral. But how does the nuclear force keep protons together, I heard ...
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If you take 200 rods of plutonium what would happen due to it’s half-life? [closed]

If you take 200 rods of plutonium then stick them together would 100 full rods worth of plutonium be remaining? And after half-life #2 here would be 50 rods worth of plutonium left and then after half-...
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236 views

Derivation of the complete Bethe Bloch formula

I can not find anywhere the explicit calculation for the complete Bethe Bloch formula including all the correction factors. I would like to have at least one idea of ​​the calculation that is actually ...