What is Pair production: Definition and 112 Discussions
Pair production is the creation of a subatomic particle and its antiparticle from a neutral boson. Examples include creating an electron and a positron, a muon and an antimuon, or a proton and an antiproton. Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus. As energy must be conserved, for pair production to occur, the incoming energy of the photon must be above a threshold of at least the total rest mass energy of the two particles created. (As the electron is the lightest, hence, lowest mass/energy, elementary particle, it requires the least energetic photons of all possible pair-production processes.) Conservation of energy and momentum are the principal constraints on the process.
All other conserved quantum numbers (angular momentum, electric charge, lepton number) of the produced particles must sum to zero – thus the created particles shall have opposite values of each other. For instance, if one particle has electric charge of +1 the other must have electric charge of −1, or if one particle has strangeness of +1 then another one must have strangeness of −1.
The probability of pair production in photon–matter interactions increases with photon energy and also increases approximately as the square of atomic number of (hence, number of protons in) the nearby atom.
We know that when a high energy gamma ray(E >= 1022 keV because the total energy of 1 electron at rest and 1 positron at rest is 511 keV) passes near a high Z(atomic weight) atomic nucleus interacts with the electrical field of the nucleus and there is a probability that this high energetic...
I was reading this interesting article [1] which talks about particle production in an expanding universe.
Usually this process is proposed to have occurred in the early universe, when the expansion was in the inflationary phase and it was so powerful that matter was created in particle...
How did you find PF?: a web search on an item I am fact-checking.
I have very little background in physics specifically. I do have a thirst for knowledge. I seek treasures in many places, when I find one I attempt to correlate and ingrate it with other tidbits I have found. I have more of a...
In most textbooks, the recoil energy of the nucleus is ignored as it absorbs so little energy, and since its main role in the reaction is to absorb some of the photon's momentum without absorbing much energy.
I'm tempted to say that the nucleus gets the maximum energy when the kinetic energy of...
If we have a photon being converted to a positron-electron pair, but we lack enough energy for this to happen (hv<2Me*c^2) but the difference is smaller than the uncertainty amount, such that tunneling may be possible, would the resultant pair have net negative energy? Would tunneling even be...
I have read on Wikipedia (https://en.wikipedia.org/wiki/Compton_wavelength) that we cannot measure the position of a particle more precise than half of its Compton wavelength, since the photon we would need will be so energetic to produce electron-positron pairs.
How does the creation of...
I know that in some Bohmian papers (like https://arxiv.org/pdf/quant-ph/0303156.pdf), electron-positron pair creation and annihilation is modeled by different methods like stochastic jumps in the configuration space. My question is, is there any Bohmian approach to reproduce all of the...
Homework Statement
What is the minimal amount of energy that a photon needs to create a muon pair?
What is the wavelength of an electron with the same total energy?
Tip: Muons have a rest mass of 1.9*10^-28kg and electrons 9.1*10^-31.
The Attempt at a Solution
I tried to use this formula...
I am not sure this question has been asked here before but I am curious about it. From the Modern Physics Course, I learned that we need a nucleus to create an electron and positron pair (with a photon). And the reason is stated as to conserve linear momentum. If this is the case then how the...
Homework Statement
One of the reasons a single photon could not produce an odd number of electrons and positrons is
a) energy would not be conserved
b) unattainable photon energies would be needed
c) matter would be created
d) charge would not be conserved
Homework EquationsThe Attempt at a...
Homework Statement
In a few more months I have to present a report about pair production in quantum electrodynamics, using Feynman diagrams.
I have been using the QFT Schwartz book, I find it a bit advanced for my level, could someone recommend me a book to study this phenomenon?.
Thank you...
I am confused about entanglement, but I am not a physicist. The concept sounds cool and I want to understand in a way so that it is familiar with what I already know. I want to know if I am interpreting this right:
1) If we have a photon that produces a pair of electron and positron, the...
In pair production, if the photon has an energy greater than 1.02 MeV, why can't a lower energy photon remain after creation of the electron-positron pair? For example, if you have a 10 MeV photon interacting with a carbon nucleus, why are the stated products of pair production the carbon...
Dear all,
I'm trying to understand the firewall controversy and the role of Hawking radiation in this. To make things concrete, I'll use the desciption of the firewall controversy of John Preskill here...
As far as I'm aware, pair production always involves the initial energetic photon interacting with another body (e.g. nucleus) to conserve momentum when creating the matter/antimatter products (e.g. electron and positron). Although "secondary" high-energy photons (e.g. ## e^+ + e^- \rightarrow...
Pair production only occurs with high energetic photons (gamma rays rather than infrared rays, because a photon needs to have a higher energy than the sum of the rest mass energies of the electron and the positron).
Where (on Earth and/or in space) does this occur? And why don't ALL gamma rays...
Homework Statement
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A proton and anti-proton are created by a photon with wavelength λ= 6.607×10−7 nm. What is the magnitude of the velocity of the newly created proton and anti-proton pair? Note, the mass of a proton/anti-proton is mp= 1.673×10-27 kg = 938.3M MeV/c2.
Homework Equations...
I am confused about the production of bosons in annihilation processes.
If we have a positron and an electron coming together and annihilating, we can always find a frame in which the net momentum is zero, which would suggest that a single photon can never be produced in such an interaction...
Homework Statement
photon collides with an electron producing a electron-positron pair, the three particles ( two electrons and one positron) move together in the same direction of the original photon.
calculate the energy of each particle.
Homework Equations
photon:
Ep=hf...
Homework Statement
I'm taking a module in Solid State Electronics and in the first chapter we went through energy band diagrams, conduction band, valence band, fermi energy level, forbidden gap, etc. Now in the notes it starts to derive some formulae for electron and hole current densities
Jn...
Does anyone know how close a photon needs to be to a nucleus (an ion really, no shielding from electrons) for pp to occur? I assume it's a probability as a function of distance, any ideas/equations?
Thanks
Assume just for this question that a neutrino has a mass of 1 ev. That is about the energy of an infrared photon with a wavelength of 1 micron. Is it possible for a visible light photon, or a more energetic photon, to create a neutrino-antineutrino pair?
A black hole evaporates through hawking radiation, what I don't get is the requirement for an energy-negative energy pair production. Since it's the black hole's gravitational energy that's responsible for the pair production, even if one of them escapes, the black hole would lose energy anyway...
Okay, please forgive what seems to be a religious debate cause I assure you it is not. I am merely seeking your opinion on an exchange.
Now, I said that pair production is an "example of creation that requires no conscious act". To this example my opponent said the following:
“Matter creation...
Pair Production questions:
1) When a gamma ray photon pair produces an electron and a positron, do the two particles always have the opposite spin? That is, one always has +1/2(h-bar) spin and the other has -1/2(h-bar) spin?
2) Other than charge and spin, what are some other notable...
Hi
I have started studying Quantum Mechanics on my own and I had a question that I am stuck on. I apologize if it's too basic or if someone else asked it
I understand what Pair Production is, but the source I am learning it from is saying that Pair production, is another way to prove the Quantum...
I would like people's opinions on why the negative energy solutions of Dirac's Relativistic Wave equation were simply ignored in 1934 to make things fit. Another related question is with the energy conservation laws as they stand. Why in pair production from a photon at 1.022MeV forming a...
Is it true that static electric field 10^16 V/cm2 is capable to create positron-electron pairs? Is this process associated with energy release? If yes, where energy comes from?
Okay so I have a problem with what my textbook is saying.
It defined pair production as a process in which a photon of electromagnetic energy is converted to a pair of particles.
But then it gave the discovery of an antiproton. Which was when a proton was accelerated to 6MeV and collided into...
Hi there,
I've been reading a textbook on Physics as applied to nuclear medicine, in particular focusing on how photons interact with matter. The textbook states (without reference) that "there are nine possible interactions between photons and matter, of which only four are of significance to...
Hi
Would it be possible to force an electron and a positron to meat each other and annihilate, then the gamma beam created is to be directed some distance away and passed next to an atom for pair production to occur. ( I dismissed complications related to the vacuums and the magnetic fields)...
In one of my classes, I should give a talk about pair production cross section in front of the class and so I'm now searching for resources. But I can't find a place where the differential cross section for pair production process is given. Anyone knows somewhere I can find it and , preferably...
Homework Statement
Two equal-energy photons collide head-on and annihilate each other, producing a u+ and u- pair. The muon mass is about 207 times the electron mass. Calculate the maximum wavelength of the photons for this to occur.
If the photons have this wavelength, describe the motion of...
Quick question regarding E-Cals. I am giving a presentation on them soon and I understand just about everything I am supposed to, but I keep encountering one symbol and I simply don't understand what it is supposed to mean.
##\frac{d\sigma}{dx}=\frac{A}{X_0N_A}\bigg[1-\frac{4}{3}x(1-x)\bigg] ##...
Why there is no electron-positron production inside the, let say, Hydrogen atom?. I know that the electric field near nucleus get modified by some form factors making it not as big as the Coulomb field, but still i think is still very big.
Q. If a photon travels in an electric field(usually by a nucleus,such as ^12C),it can spontaneously disintegrate into an electron and a positron--known as pair production.
A)Calculate the smallest possible photon frequency that produces pair production by assuming that both electron and positron...
Does pair production use helium nuclei for matter creation?
Pair production occurs when a photon (Light Particle) strikes a heavy nucleus, it disintegrates and produces a pair of an electron and a positron. Is that heavy nucleus of Helium?
Homework Statement
http://puu.sh/brbpb/3c7573fa32.png
Homework Equations
E = (mc^2 +K + mc^2 + K)
P = E/c
E = mc^2
The Attempt at a Solution
The book says that the momentum/kinetic energy of the electron and positron produced in a pair production is so small that it can be...
Hi all,
I'm currently studying pair production by two photons (a high-energy one traveling in a isotropic field of low-energy ones), and I'm trying to understand the energy range of the electron created by this phenomenon.
For this, I'm studying an old paper from Aharonian 1983...
I have a question regarding the calculation of the cross section in muon pair production from electron positron annihilation.
After some calculations the textbook comes to the conclusion that the differential cross section is approximately equal to:
(1+cos(theta)^2)alpha^2/(4*s)
where alpha...
I don't completely understand why an electron positron pair cannot be created from an isolated photon. I understand it must have something to do with 4 momentum conservation, but I really can't see a problem given the photon has enough energy for the mass to energy vice versa conversion.\
The...
Hi there,
My homework problem is on particle physics and asks me to draw a feynman diagram for pp→\bar{t} t interaction, which is what I think the LHC is planning to do (or possibly is doing).
For the more traditional interaction; \bar{p} p→\bar{t} t I have this diagram;
In this...
Homework Statement
How much photon energy would be required to produce a proton-antiproton pair? Where could such a
high-energy photon come from?
Homework Equations
E^{2} = (pc)^{2} + (E_{0})^{2}
The Attempt at a Solution
Since the photon is massless its energy is
E_{i}=pc
The final...
hi,
i just need a quick clarification on pair production.
from my limited understanding, a photon of sufficiently high energy (gramma ray with energy at least equal to the mass of both an electron and positron at rest) will interact with a nucleus in ways that i do not understand to...
I'm having a bit of trouble understanding why a nucleus is needed for a gamma ray to interact with in particle pair production. I know that all properties are conserved - spin, charge, etc. -, and I know that the photon must have at least the energy of twice the standing energy of the particle...
Hi there.
Just a few quick questions:
What causes a photon to become an antimatter / matter pair? Is it just random? Can a photon be influenced to encourage it to change? Also what is the process called? Do we say the photon has decayed? That doesn't seem right to me.
In addition, if...
Allover the web i am only seeing a statement similar to this:
"Pair production is not possible in vaccum, 3rd particle is needed so
that conservation of momentum holds."
Well no one out of many writers shows, how to prove this matematically. So this is what interests me here.
First i wanted...