Nuclei Definition and 136 Threads

I've started studying physics at a basic level and I've ready that beta decay takes place when the number of neutrons exceed the number of protons in a nucleus. Why does this excess number of neutrons compared to protons make the nucleus unstable? Also, what does an unstable nucleus mean?

Homework Statement in the photo, the 23Na form 24Na Am i right? if i am right, the mass of 23Na should decraese , and mass of 24Na should increase. but why the solution provided is the mass of 24Na decreses and increases at the time of delta t ?? i can't understand Homework EquationsThe...

Homework Statement There is this university exam question: Draw the nuclear binding energy curve and and show that energy is released when a heavy nucleus of A> 200 breaks up into two nearly equal fragments. Homework Equations See below. The Attempt at a Solution I found in an example in...

Homework Statement The Ground state wave function governing the motion of a pair of vibrating nuclei looks like: wave function = wave (x) = (a/pi)1/4 e-ax2/2 where a = alpha = mu*w/(h bar), which is determined by mu = reduced mass of the pair where w = angular vibrational frequency ...So...

I am interested in the topic of the thread https://www.physicsforums.com/showthread.php?t=768539 ,especially for those unpair 1p1n case. As I know, for the simplest case deuteron, the Jπ (groundstate here and later) is 1+ but 0+. This is very different to the atomic physics case. For He...

Hi Based on what I know (it might be wrong) properties of nuclei are calculated based on the different (simplified) models of the p and n "particles" (shells, droplets etc). I have 2 questions: 1. To what extent can we assume that n and p are "elementary" particles bound by residual strong...

Homework Statement Radioactive nuclei are produced in an irradiated sample at the rate of 10 s-1. If the number in the sample builds up to a maximum of 1000, calculate the mean life and the half-life of the radioactive nuclei Can anyone advise on this one not sure how mean life is found...

^{62}Cu is 61.932586 amu. I would like to know how many exposed nuclei are in 1.0 gram of ^{62}Cu. I have two calculations below, hopefully one of them is correct... Method 1. 1.0 gram ^{62}Cu x \frac{1 kg}{1000 g} x \frac{1 amu}{1.660566 x 10^{-27}kg} x \frac{1 mole ^{62}Cu}{61.932586...

I came across a worked example question in a particle physics book this morning that had a beam of neutrinos of energy 2.3MeV incident on a lead target. The point of the question was calculating the thickness of lead needed to reduce the beam intensity by a certain fraction - and the solution...

Homework Statement To study the structure of the lead nucleus, electrons are fired at a lead target. Some of the electrons actually enter the nuclei of the target, and the deflection of these electrons is measured. The deflection is caused by the charge of the nucleus, which is distributed...

Homework Statement Nuclei of radioactive element A are produced at rate t^2 (where t is time) at any time t. The element A has decay constant λ. Let N be the number of nuclei of element A at any time t. At time t=t0, N is minimum. Then N at t0 is what? The Attempt at a Solution N(t) = kt^2...

Hello, I came across the name spherical even even nuclei in an exercise about the hyperfine structure. What does it refer to? That the number of protons and the number of neutrons are both even? So that there is no nuclear magnetic moment?

As I mentioned, I want to know if the cahrge distribution of nuclei has any influence on electronic properties. And what can cause a change on the nuclear charge distribution!

An electron doesn't move in an orbit round the nucleus. It is in a diffused state. Please explain what is the meaning of this statement and what is diffused state.

I know that in order to create a high-spin nucleus, that you slam a nucleus into the target nucleus off-center so that when they fuse, it has a large angular momentum (relatively speaking). However, can't you add angular momentum to the target nucleus by instead just shining...

What are the strangest known nuclei? Specifically, have any nuclei with strangeness over 3 been seen? Are there any known charming or beautiful hypernuclei? Considering that Be-8, with half-life 10-16 s is a well described nucleus, the 10-12...10-13 s lifetime of charming and beautiful...

Why is it that those atoms, with atomic numbers of 90 and 92 have much, much longer half lives than atoms like Radon, Radium, and Polonium? I do realize that atoms with even atomic numbers are more stable than ones with odd numbers, so it makes sense why atoms like astatine, actinium, and...

Basically I'm trying to find out how to find the maximum distance between two deuterium nuclei in order to overcome the coulomb barrier, causing them to fuse. Thanks

Homework Statement Two nuclei make a head-on elastic collision. One nucleus (mass m) is initially stationary. The other nucleus has an initial velocity (v) and a final velocity of (-v/5). What is the mass of this nucleus? Homework Equations conservation of momentum...

This probably seems naiive, but why? My main question being that why isn't hydrogen the most stable. It is the simplest and should be, right? If everything wants to arrive at the lowest possible energy state, why do nuclei want to arrive at iron? I can understand splitting atoms (fission)...

Both the strong and weak interactions are short range forces of approximately 1 fm. Two protons are separated by this distance. Which equation should i use for these two question? i) The strength of the electrical and gravitational interactions that influence each of these protons. ii)...

Why do different nuclei need different neutron speed to achieve fission?? My understanding is that U-235 requires a thermal neutron in order to be likely to cause a fission reaction, however Pu-239 requires the additional energy of a fast neutron in order to cause the nucleus to undergo fission...

I have had a question that I cannot get an answer for. I recently had an exam for energy in the nucleus which included a question about why lead nuclei would be inadequate for use as a moderator in a reactor. When I got the answer for the question, it stated that the lead nuclei reflect neutrons...

Homework Statement Calculate the typical energy of nuclei in solar core. Calculate thermal energy required for a proton to overcome the Coulomb barrier and get within range of strong nuclear force (10^-15m) Homework Equations None given The Attempt at a Solution I have the core...

Homework Statement A small animal bone fragment found in an archaelogical site has a carbon mass of 155g. When the animal was alive, the ratio of radioactive 146C to the stable 126C was 1.31×10-12. What was the number of 146C nuclei found in the sample when the animal was alive? Homework...

and nuclei are so small(on an atomic level!). is it that there are SO many atoms around and that thermal neutrons are still incredibly fast, that if there is a reflector surrounding(lets say we're talking about a critical mass of uranium and an uncontrolled chain reaction), that the neutron will...

Homework Statement http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_s07_qp_1.pdf question 40 Homework Equations The Attempt at a Solution I got D, because the heaviest should have the lowest speed. But I am wrong. dnt know why

"Neutrons don't decay in nuclei because no available states" incorrect? Hello, If I understand correctly, the argument for a neutron (usually) not decaying when in a nucleus, is that the resulting proton would then have to occupy a high energy level, the lower levels already being occupied...

When two deuterium nuclei are shot at each other they have some probability of fusing into a He nuclei. At the start we have a proton and a neutron in a potential well 1 MeV deep and another proton and neutron in another well 1 MeV deep. At the end we have two protons and two neutrons all in a...

Homework Statement What is the molar binding energy of uranium 235 nuclei? Givem: The mass of 1 uranium nuecli is 235.0439u Homework Equations E=Δmc^2 The Attempt at a Solution mass of nucleons: m=92P+143n=236.90814u mass of nucleus: m=234.99343u...

I've gotten interested in this pair production stuff, and I'm wondering: Why is it that some nuclei can absorb more energy than the energy needed for pair production, while other nuclei result with the incoming energy creating pair production? Is it because heavier nuclei can distribute the...

Homework Statement "What force keeps the electron from falling into the nucleus of the atom?"Homework Equations The Attempt at a Solution I have three hypotheses: 1. Neutrons have a negative charge (although there is not only electron capture but also b+ decay) 2. The electrons in the...

Is stable nuclei decay? if no then how and why know please ans me i am waiting

As a layperson...(Who is trying to understand the atom in a bit more detail). In the past, I have most often seen the atoms drawn with electron clouds that have bands of varying density. I understand the density of the bands represent areas of higher probability. I have often seen models...

In light nuclei an apparent hyperfine anomaly can seem to be present. This is however due to the quantummechanical zero-point motion of the nucleus. Is it possible to correct for this zero-point motion in experiment?

Hi, I need recent experimental data for mass radii of the nuclei of deuterium, tritium, helium 3 and helium 4. I would be grateful if someone could help me with this problem and gave me exact quotes from articles, books, etc. scientific sources.

1. Rank from greatest to least the reduction of mass per nucleon that accompanies the fusion of the following pairs of nuclei: a. Two hydrogen nuclei b. Two carbon nuclei c. Two aluminum nuclei d. Two iron nuclei 2. n/a 3. I know fusion is when two elements are combined and...

I know odd-odd nuclei are generally unstable against beta decay as the pairing term in the semi-empirical mass formula is less than zero, and I know even-even nuclei are generally stable, but I don't get the rules you apply for even-odd or odd-even nuclei. Do you have to work out the binding...

why the electron does not stick to the nuclei?

It's hard to me to understand about the interaction between protons and neutrons by the means of entropy. And Is it possible to know about an entropy of an interaction between protons and neutrons or between quarks:biggrin:?

Are collapsed nuclei, like are discussed in http://prd.aps.org/abstract/PRD/v4/i6/p1601_1" still thought to be possible?

Q.) What would happen if a *reverse-Tokamak* was created, thus reversing the electromagnets to a negative charge and repelling electrons into each other instead of fusing hydrogen nuclei, what approximate temperature would need to be used and would it work? If so what would occur?

How do you define (by all means) the kinetic energy of a nuclei (let's say of proton)? What are the factors, equations, and other things involved?

I am aware that fusing two iron nuclei together is highly endothermic. But at what temperature does it begin. Does anybody have a clue? I know that fusing two hydrogen nuclei begins at 10 to 14 million Kelvins and that helium fusion begins at 100 million Kelvins. It wouldn't surprise me that...

My question: do there exist particles similar to atomic nuclei, but made only of neutrons? If not, then why? I suspect that this would be beta-unstable, but it should live for some time and get observed somehow.

a nuclear reaction Q value is the difference in kinetic energy of the final particle and the initial particle. how we can determine the kinetic energy only for the recoil nuclei if the kinetic energy of other particles are not given?

We all know that for an ensemble of particles we can use the exponential decay law. However, the problem I am working on requires to look at nuclei from an atomic perspective. Wikipedia says that this is a stochastic process on the atomic level. I do not have much knowledge of stochastic...

What's the difference between them?

Hi, I'm in my last year of school and part of my A-Level is on nuclear physics. We've recently studied binding energy and I noticed that the elements with the highest binding energy per nucleon (the most stable nuclei) are magnetic - iron, cobalt and nickel. Are binding energy and magnetism...

Problem For Structure of Nuclei -- Enigmatic ! Question :- calculate the distance of closest apprach for a head on collision between 5.30Mev alpha particle and nucleus of a copper atom? Answer The distance of closest approach is given by...