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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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Geant 4, simulate Tc-99m decay

I have a setup of Monte Carlo simulations in Geant4, and I'm able to simulate radioactive events from isotopes such as I-131 and F-18, which are defined in the RadioactiveDecayData5.2 files. Tc-99m ...
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The energy mass equivalence relation [on hold]

I wanted to know that what is the reason we believe that the energy mass equivalence relation i.e. E = mc^2 is true? What experiments other than that on the nucleons, compels us to believe this is ...
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By how much are various dibaryon states unbound?

It has been known for a long time that the deuteron is stable but the dineutron (nn) and diproton (pp) are not. Many textbooks comment on this, but all the ones I found so far do not give quantitative ...
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Translation of a Physics Dutch text [on hold]

I am having troubles trying to understand this text (Google Translator does not help this time). Please let me know of another site if you consider that this question is not appropriate for PSE. ...
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Potential Energy of proton as per Quark Model

In a quark model of elementary particles, a proton is made of two up quarks [charge (2/3) e] and one down quarks [charges –(1/3) e]. Assume that they have a triangle configuration with side length of ...
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How does the shape of radioactive material effect its critical mass?

If critical mass is defined by the amount of fissile material required to sustain nuclear fission. Assuming a subcritical mass object, and knowing radioactive materials can merely by chance break ...
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How many known nuclides are there?

What is the current estimate for the number of nuclides? This is a very basic question, but I'm finding it remarkably hard to get a reliable, up-to-date answer. A few books published in the last 2-3 ...
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Is there more iron or nickle in the core of a pre-supernova star?

For stars that undergo core collapse (leading to a core-collapse supernova or direct blackhole formation), the final stage of nuclear burning is silicon burning. Most online references I've found ...
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Z effective for compouds [closed]

How to use Manohara equations (set of formulas for all types of materials for calculation of the effective atomic number and electron density). how to use it for protons and other charged particles.
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Why does the binding energy curve ever decrease?

So the way I understand binding energy is that if I have two nucleons and I let the come together, they’ll decrease their potential energy as they move closer and this will speed them up as they’re ...
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Why is iron the peak of the binding energy curve?

If Nickel-62 and Iron-58 have more binding energy per nucleon than Iron-56 does, then why is iron-56 shown as the peak of the binding energy curve? Also, does adding neutrons always make the atom more ...
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Why does 'The electron density builds quadratically with distance from the nuclues.'?

I found the statement above on this useful website. http://photonicswiki.org/index.php?title=Atomic_Orbitals_and_Nodes But I am confused. Why would that be the case? Is this based on some exotic ...
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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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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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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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2answers
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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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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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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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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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1answer
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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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2answers
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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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2answers
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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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3answers
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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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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
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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
54 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
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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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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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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
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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
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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
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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
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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
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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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1answer
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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
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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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1answer
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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
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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
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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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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
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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: $$\...