Questions tagged [nuclear-physics]

Nuclear physics is the study of the composition, behavior and interaction of atomic nuclei and their constituent parts.

Filter by
Sorted by
Tagged with
1
vote
1answer
60 views

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 ...
1
vote
1answer
62 views

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 ...
0
votes
0answers
56 views

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.
2
votes
2answers
67 views

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 ...
1
vote
2answers
130 views

Are human beings radioactive?

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 ...
3
votes
1answer
133 views

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 ...
0
votes
2answers
63 views

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 ...
0
votes
0answers
98 views

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 ...
4
votes
1answer
294 views

Possible to detect presence of nuclear bomb? [closed]

Take, for instance, a W-80 nuclear warhead. Does technology exist, say in the form of a satellite or drone, that could detect the warhead's presence (assuming it's not enclosed in some kind of ...
-2
votes
1answer
53 views

About nuclear energy levels

The energy level of a heavy atomic nucleus such as that of uranium, which is related to the zeta function, is determined by taking a discrete value, but cannot it be represented by an equation like an ...
9
votes
3answers
262 views

What experiments show that the nucleus is spherical in shape?

I know that experiments like electron scattering can give the nuclear charge radius and proton scattering can give the nuclear matter radius. However, these experiments seem to first assume that the ...
1
vote
2answers
71 views

Is the interaction $\gamma p \to \pi^+n$ allowed?

I'm doing an undergraduate lecture course in particle physics and I'm still getting to grips with the basics of interactions. One of the example interactions I've been given in an exercise is $\gamma ...
0
votes
1answer
35 views

Is there a definition for describing nuclear material undergoing fission/fusion? [closed]

Is there a term similiar as a piece of coal burning as ambers? Can nuclear material undergoing the reaction be transported?
-1
votes
1answer
114 views

How to convert MeV to velocity? [closed]

For example, in the fission process: $${}^{235}\mathrm{U} + n \rightarrow {}^{140}\mathrm{Xe} + {}^{94}\mathrm{Sr} + 2n$$ the masses in atomic mass units are: \begin{align} M\left({}^{235}\mathrm{...
0
votes
0answers
67 views

Gamma from U238 decay chain

Where can I find detailed information on the gamma background from the U238 decay chain? Edit: Thank you for your replies. I need to find all the branching ratios and extract information of all the ...
0
votes
1answer
21 views

Why do half lives of Carbon isotopes vary by a great extent?

Both Carbon-14 and Carbon-15 decay by the $\beta^-$ mechanism but the half life for $C^{14}$ is approximately 5500 years whereas that if $C^{15}$ is around 2 seconds.What causes this disparity in ...
3
votes
1answer
57 views

Why atoms do not radiate energy? [duplicate]

In atoms electron moves in a circular motion with constant velocity but in circular motion acceleration is produced when we change direction so we cant get constant velocity. So why electron do not ...
0
votes
2answers
63 views

Conserved and invariant quantities in a nuclear reaction

For a reaction $$a+X\rightarrow Y+b$$ in the book, Introductory Nuclear Physics by Krane, he has written that the total energy and the total momentum both in RHS and LHS remains conserved in Lab frame,...
0
votes
1answer
87 views

How does the shape of a 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 ...
0
votes
4answers
80 views

Difference between Mass Number and atomic mass unit (AMU)

I am struggling to understand the difference between Mass Number and atomic mass unit (AMU). I read several posts on this site but still confused. Mass Number seems like a number (i.e. number of ...
4
votes
3answers
387 views

Spectrum of beta decay

I have a very simple question regarding the emission spectrum of a beta decay: Why does the $\beta^+$-spectrum start at $0$ but the $\beta^-$ doesn't? This would mean that there are a bunch of ...
3
votes
1answer
43 views

Thickness of a target bombarded with deuterium

I need to calculate de thickness of a sheet of Zinc that is being bombarded by deuterium nuclei. I'm given that the fraction of nuclei dispersed below $\theta=90º$ with $T=8MeV$ is $0.9999$ and the ...
0
votes
0answers
37 views

Proton-Proton, CNO, or white dwarf matter fusion reactor: Is it vaguely possible?

I understand that all efforts at present to make fusion work as an energy source have used light nuclei other than protons due to the fact that the cross section of the proton-proton reaction is just ...
0
votes
1answer
45 views

Energy budget of of proton-proton fusion (p-p chain)

How much energy is released in the first nuclear reaction of the p-p chain which produces energy in lower-mass stars like the Sun? The value of 1.44 MeV is given in many sources, but I don't ...
0
votes
0answers
55 views

What are the nuclear shell assignments for the odd neutron and proton in $^8B$?

I am having some trouble assigning the odd proton and neutron to the appropriate nuclear shells in the $^8B$ nuclide formed in the $^7\mathrm{Be}(p, \gamma)^8\mathrm{B}$ reaction in the solar plasma. ...
18
votes
2answers
5k views

Why does this quiz question say that protons and electrons do not combine to form neutrons?

I read this somewhere: Where are the protons and electrons in a neutron star? When the neutron star forms, most of the protons and electrons combine together to form neutrons. But on a true/false ...
2
votes
1answer
121 views

Why is the electrostatic energy of a nucleus proportional to $Z(Z-1)$?

The complete binding energy is (more details in Krane's book, page 68): $$B = a_v A - a_s A^{2/3} - a_c Z(Z-1)A^{-1/3} - a_{sym} \frac{(A-2Z)^2}{A} + \delta$$ I want to explain the $Z(Z-1)$ term. ...
2
votes
0answers
39 views

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 ...
1
vote
1answer
34 views

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 ...
0
votes
0answers
64 views

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 ...
0
votes
0answers
47 views

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 ...
0
votes
1answer
56 views

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 ...
3
votes
0answers
26 views

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 ...
0
votes
1answer
86 views

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 ...
19
votes
2answers
5k views

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 ...
0
votes
2answers
38 views

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 ...
9
votes
1answer
109 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 $^...
1
vote
2answers
110 views

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 ...
1
vote
2answers
61 views

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 $\Delta L=0$?
2
votes
1answer
129 views

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 ...
0
votes
1answer
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 ...
1
vote
2answers
37 views

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 ...
8
votes
5answers
856 views

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 ...
0
votes
1answer
50 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}{...
0
votes
2answers
75 views

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 ...
0
votes
0answers
34 views

Elements Of the periodic table [duplicate]

Why even-numbered elements, with their even proton numbers are more abundant than odd-numbered elements ?
96
votes
11answers
15k views

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. ...
8
votes
1answer
1k views

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? ...
1
vote
1answer
76 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 ...
2
votes
2answers
62 views

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, ...