# 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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### Scaling of nuclear and electromagnetic force

The Wikipedia article on alpha decay stated: The strength of the attractive nuclear force keeping a nucleus together is thus proportional to the number of nucleons, but the total disruptive ...
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### Why is the actual KE value smaller than what I calculated?

Problem The nuclear equation for the decay of calcium-47 into scandium-47 is given by: The following data are available: Mass of calcium-47 nucleus = 46.95455 u Mass of scandium-47 nucleus = 46....
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### Example of calculating phase shifts in scattering theory

I have an extended question to this post: Phase shifts in scattering theory I have read it and also went over the formalism in Sakurai's, Shankar's, and Griffith's. I am now trying to look for ...
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### Fusion Kinetic Energy

In fusion, the mass of the reactants is greater than the mass of the products. Thus, mass is lost in fusion. My thinking was that this mass defect is converted into binding energy that is then used to ...
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### Are particles that are moving at the fermi energy easier to remove if you model a nucleus as a fermi gas?

Due to the Pauli exclusion principle, the nucleons build up the energy states from the bottom up. When talking about binding energy per nucleon, you are talking about how much energy is needed to ...
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### Tritium decay energy too small for quark model

So $^3$H turns into $^3$He through $\beta^-$ decay, right? The energy of this reaction is only 18.6 keV. However, according to the constituent quarks model, the only thing different between $^3$H ...
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### Why does stability come from binding energy and not mass

The mass of a nucleus is given by: $$Mc^2=n M_n c^2+zM_pc^2-B(z,n)$$ And we were told that nuclei want to maximise the binding energy per nucleon. However, I don't see why they don't want to ...
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### Why is the energy taken to free neutrons irrelevant to the energy released in a fission reaction?

Our teacher is currently teaching nuclear physics and I am confused on the process of calculating the energy released in a fission reaction. An example given in class is as follows: Uranium-235 + 1n -...
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### How much radiation do nuclear physics experiments expose researchers to nowadays?

I am curious about how much radiation do experimental nuclear physics researchers/students suffer in nowadays research environment. I know this may be a dumb question, but I have can found answer ...
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### Why does nuclear energy level with higher j(total angular momentum quantum number) always lie below the smaller j? [closed]

Here i don't understand the reason for the energy level with j=l+1/2 lies below the j=l-1/2 .From the shell model i see this and it is also written in my book that energy level with higher j lies ...
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### Gold nucleus vs. M87 surface gravity

I tried to solve this gedanken problem, but I get a nonsense solution (may be is non resoluble). Take a gold nucleus. Nuclear radius is about $R=7.2 \:\rm fm$. Consider it a solid rigid sphere (I ...
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### What is the reason of decreasing portion of the curve of the daughter atom as shown below after reaching a maximum point? [closed]

Here A is the parent atom and B is tha daughter atom
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### If all we need to do is bombard with alpha particles then why can't we do nuclear fusion like that in the star?

In Chadwick's experiment, alpha particle from a source are bombarded on beryllium atom and fusion occurs to produce carbon atoms. My question is that if it is that easy to cause nuclear fusion, then ...
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### What are reasonable sets of theoretical values for mass and uncertainties of quantum particles

So I have equations of $\Delta x(t)$ that involve the uncertainties of the positions of two masses at $t = 0$, uncertainties in momenta, and the masses of the particles. The equation is complex enough ...
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### Is making nuclear bomb using natural uranium possible?

I know that the critical size of natural uranium metal with graphite moderator is about 27 tons "oak ridge graphite reactor". for comparison highly enriched uranium have only 17 kg critical size with ...
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### If binding energy (from mass defect) is essentially the strong nuclear force maintaining the nucleus, why is it released?

I am aware that during nuclear fusion for light elements and nuclear fission for heavy elements, the resultant elements have less mass than the original reacting elements (ie the mass defect) because ...
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### Spin Orbit Coupling term

I was seeing this enlightening video of DrPhysics on Spin Orbit Coupling: https://www.youtube.com/watch?v=aftOY3OkAgA&list=PLF15670EECA944A13&index=9 And I think there is a mistake. Around ...
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### Mossbauer effect: neglectable recoil or absolute no recoil?

I stumbled on the Mossbauer effect. From the wikipedia article, I cannot tell for sure if the momentum of recoil is really zero, or only neglectable. From what I do (think I) understand, the ...
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### Why doesn’t the beta particle stay in the nucleus

When a neutron splits into a proton and an electron during beta decay, why does the electron fly out? Should it not stay close to the oppositely charged protons?
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### Why does the nucleus not repel itself? [duplicate]

If the nucleus is densely positively charged, why don’t the protons in the nucleus repel from each other and move towards the orbiting electrons? Because each proton is not only being repelled by the ...
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### Fission inside nuclear reactor

I have studied about nuclear reactors and also know their functionality.But some how i couldn't get answers for some my questions. 1) During fission reaction enormous amount of heat is produced and ...
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### Why does $S_p$ increase for closed neutron shell?

I'm taking an introductory nuclear physics course in which we just covered the shell model. In that model, the so-called magic numbers arise as a consequence of there being an energy level gap due to ...
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### Why is energy released during fission reactions?

If the energy released during a fission reaction is the binding energy then what energy is left to bind the nucleons together? I'm very confused if there's a better explanation on fission I'd ...
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### What exactly is binding energy?

I've been reading on radioactivity but along the way I got confused, if binding energy is the amount of energy used in holding the nucleus together then why is binding energy also the amount of energy ...
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### Relaxation/thermalization of High spin nuclei

Is it practical to keep nuclei excited to high spin for long(ish) times? What mechanisms drive the relaxation of nuclear spin? Which texts would treat this subject with detail?
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### Why did the Lockheed Martin compact fusion reactor failed? [duplicate]

What made the compact fusion reactor to not be compact. What assumptions did lokheed made in its simulation that showed that it could work. Can we do anything that could make it work or it is ...
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### Is it possible to trigger a nuclear reaction with physical force?

In Mission Impossible Fallout, they're dealing with 3 plutonium cores. If one of those cores was thrown against a wall by Ethan Hunt, could it start a chain reaction and explode? For that matter, ...
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### Can a quark quantum tunnel outside a nucleus?

I read that a particle wavefunction can extend over a thin barrier and there is a probability of finding it over the barrier even though it doesn't have the necessary energy, what about quark?
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There are several ways to define the radius of a nucleus, one of which is the mean square radius: $$\langle r^2 \rangle = \frac{\int r^2 \rho (r) d\tau}{\int \rho (r) d\tau}$$ What is the ...
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### Angular Momentum Coupling and 3jm Symbols

I have a question regarding j coupling. At the moment, I try to learn the diagrammatic approach which is written down in Varshalovich, Chapter 11. But there I have now a question regarding the ...
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### How would you calculate the half-life of a source with one long measurement?

I'm working on a project, and I understand that half life of a source is typically calculated with time intervals (eg 5 sec intervals for 20 minutes) and then using that data to find the decay ...
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### Element creation in space

In my astronomy magazine I recently saw the periodic system revisited where the elememnts were color-coded according to their production site. For example, Hydrogen was created from the early Universe ...
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### Quantised energy levels of the nucleus

We know that the atomic energy levels are quantised since the nucleus has a potential of its own and solving the Schrödinger equation we can see that. But in gamma emission we see that the origin of ...
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### Estimating Accidental Coincidence

I am trying to measure muon's mean lifetime using 3 scintillators. The logic of the experiment is shown below: I know that accidental coincidences could happen because of unrelated muons that ...
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I am given the following question: 228-88 Ra is an isotope of Radium. A-Z Ra is a neutral atom of a different isotope of radium. State the possible value for A and Z. The value for Z is 88 ...
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### Binding Energy and Energy Released

Let's say that we have a nucleus with 7 units of mass. And let's say that the combined mass of its constituents is 10 units. The 3 units contribute toward the "binding energy." However, we do know ...
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### Nuclear Feedback Loop (Fusion and Fission)

What are the main factors that prevent a feedback loop being created by using a hybrid method of fission and fusion. Fusion building up to fissionable materials, and fission breaking down till fusion ...
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### Why does the potential energy between two daughter nuclei not give the binding energy per nucleon?

I have attempted a nuclear physics question, given below: Calculate the electrostatic potential energy of two fragments, a Cesium and a Zirconium nucleus, when separated by a distance $2D$, twice ...
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### Differential cross section in nuclear reaction

While explaining Compound Nucleus Mechanism of Nuclear Reactions, our professor gave us the graph that I have posted in the picture above. However, no further information was given or explained. I ...
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### Why the National Ignition Facility try to use 192 laser beams to trigger ignition without heat capsule?

In the discussion of the question "Nuclear Fusion with extremely high pressure and low temperature", the conclusion is only ultrahigh pressure cannot trigger fusion. But why does NIF try to use 192 ...
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### Can free protons show $β^+$ decay if provided with energy?

I'm studying introductory Nuclear Physics in school and we were taught that free protons never undergo $β^+$ decay since the mass of neutron is greater than mass of proton, so the $Q$ value of the ...
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### is possible to create a nuclear fusion using simple electric arc discharge?

If we have a simple discharge tube filled by deuterium gas or even heavy water, and put tungsten electrodes close to each other to create a huge electric field, then using a megavolt generator to ...
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### What is the formula of operating voltage of GM counter?

In some manuals I found operating voltage formula $$V=V_1+(1/3)(V_2-V_1)$$ and in other manuals $$V=(V_2+V_1)/2.$$ Which formula is correct? If both are correct, then please give the reason.
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### How is mass of neutron compared with proton when it is inside the nucleus? [closed]

The mass of free neutron is around 0.1% more than the mass of proton. When it is bound inside the nucleus, neutron mass is less compared to its mass in free state. The question is how much mass it ...
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I am reading "The greatest story ever told - so far" by Lawrence Krauss. He starts chapter 9, Decay and Rubble, telling how he was shocked when he realized that humans are radioactive. When I first ...
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### Where is nuclear fusion occuring in the Sun?

My understanding is that the sun is basically a sphere of hydrogen with a helium core, and that the hydrogen is undergoing nuclear fusion to produce helium. There are many images and cross-sectional ...
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### Strong force and radioactivity [duplicate]

Why does adding more neutrons to an atom unstabilise it? Won’t adding more neutrons increase the strong force and thus knit the nucleus more tightly? Or is it because it’s being added in a particular ...
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### Discussion about a new nuclear fusion design [duplicate]

Let me clarify here, this is not cold fusion. D&T gas will be compressed very rapidly and its temperature will increase very fast. So, I don't think this is a duplicate question. I have a new ...