Photon interactions in matter kinematics interaction cross sections energytransfer cross sections mass attenuation coefficients compton effect photoelectric effect pair production rayleigh coherent scattering photonuclear interactions compton interaction inelastic photon scattering by an electron. The electron departs with most of the energy from the photon and begins to ionize surrounding molecules. It is one of the principal ways in which highenergy gamma rays are absorbed in matter. If the gamma rays interact in the detector via pair production so that both 511 kev annihilation photons escape the detector the energy deposited in the detector is the original photons come directly from source pair production double and single escape. The electrons scattered photoelectric effect or compton scattering or generated pair production by one of the three basic interactions excite a certain number of electronhole pairs and are responsible for the peak formation. Interactions of photons with matter pair production. Pair production takes place a only in presence of nuclei b only in a vacuum c only in solids d none of the above 20. Ppt compton scattering powerpoint presentation free to. The pair production is one of major interaction of gamma with matter. The first of these is the compton effect, named after arthur holly compton who received the nobel prize for physics in 1927 for its discovery.
This gives rise to characteristic xrays that can be used to identify. Photoelectric, compton scattering, thomson and pair production and photo disintegration. Effect rayleigh scattering pair production nucleus compton pair production electron. Schematic diagram about the process of pair production is shown in figure 1. In this process, termed pair production, a photon can simply.
Pair production two annihilation photons created, each with 0. The photon transfers practically all of its energy to the electron and ceases to exist. What is the difference between photoelectric effect and. As the photon interacts with the strong electric field around the nucleus it undergoes a change of state and is transformed into two particles essentially creating matter from energy. Pair production is a direct conversion of radiant energy to matter. Compton scattering, pair annihilation and pair production.
The third process of ionization is known as pairproduction. Only the three most important absorption processes are considered. Lecture 1 photons, the photoelectric effect, compton. Theory of the compton effect michigan state university.
Compton effect and pair production linkedin slideshare. Pair production is only possible for photons with energies greater than 1022 kev. This is the main difference between photoelectric effect and compton effect. Photon interactions in matter university of toledo. In this process, the initial photon energy is very high, normally occurring at energies of 1. Compton scattering is an example of inelastic scattering of light by a free charged particle, where the wavelength of the scattered light is different from that of the incident radiation. The other effect deals with the radiation emitted when a tightly bound electron from a heavy element is kicked out by a photon. Photoelectric effect in this process, an incoming photon undergoes a collision with a tightly bound electron. Pair production can only occur if the incident photon energy is at least 1.
The compton effect compton scattering and gamma ray. Compton effect, photoelectric effect and pair production. Based on a lot of einsteins work including his special theory of relativity, physicists. Pair production pp, like the photoelectric effect, results in the complete attenuation of the incident photon. Compton effect, increase in wavelength of xrays and other energetic electromagnetic radiations that have been elastically scattered by electrons. Compton scattering, pair annihilation and pair production in a plasma vinod krishan indian institute of astrophysics, bangalore 560034, india abstract. Photon interactions in matter kinematics energytransfer cross sections mass attenuation coefficients compton effect photoelectric effect pair production rayleigh coherent scattering photonuclear interactions compton interaction inelastic photon scattering by an electron main assumption. Compton effect article about compton effect by the free. In general the cross section increases approximately with the square of atomic number. Pair production is the dominant photon interaction at high energies gt 10 mev in order to create a pair, the photon must have gt 2me 1. The corpuscular description of electromagnetic radiation is the most appropriate for these effects, as one photon in a wellcollimated beam of n 0 photons disappears at each interaction. The effect has proved to be one of the cornerstones of quantum mechanics, which. Difference between compton effect and photoelectric effect and pair production.
National bureau of standards report 1003, washington, d. For example, in lead the compton effect makes the main contribution to the energy loss of photons at energies of the order of 110 mega electron volts, or mev in a lighter element, aluminum, this range is 0. The square of the four momentum of a photon in vacuum is zero. Review of theory of compton, photoelectric, and pair production cross sections, and of coherent and incoherent scattering. The photoelectric effect is a quantum electronic phenomenon in which electrons are emitted from matter after the absorption of energy from electromagnetic radiation such. Pdf entangled electronphoton pair production by channel. Tables of theoretical atomic cross sections for coherentplusincoherent scattering. These two new photons continue to go through ionization, eventually producing the compton effect, and finally diminishing to the photoelectric effect and total absorption.
Find materials for this course in the pages linked along the left. Pair production the differential cross section has the form fractional energy transfer to the electronpositron k incident. In addition to these primary processes, there are several lesser ways such as xray production and bremsstrahlung. The photoelectric effect is a low energy phenomenon, and the interacted photons disappear just after they deliver their energy to electrons. In addition to the photoelectric effect photon absorption and compton scattering photon scattering, there is a third process by which photons can lose energy in their interaction with matter. Lecture notes applied nuclear physics nuclear science. However, in an unmagnetized plasma it is equal to the square of the plasma frequency. Entangled electronphoton pair production by channel. The compton effect lesson 9 objective explain, qualitatively and quantitatively. Entangled electronphoton pair production by channelexchange in highenergy compton scattering basudev nag chowdhury1, sanatan chattopadhyay1 1department of electronic science, university of calcutta, india email address.
Entangled electronphoton pair production by channelexchange in highenergy compton scattering preprint pdf available september 2019 with 40 reads how we measure reads. The main difference between compton effect and photoelectric effect is that the absorption of energy from incident. R x ray attenuation coefficients from 10 kev to 100 mev. Pair production the pair production is a crucial example that photon energy can convert into kinetic energy as well as rest mass energy. The compton effect is studied with the measurement of a gamma ray energy spectrum using a scintillator, photomultiplier tube, and multichannel. Difference between photoelectric effect and compton effect. Compton effect the compton effect occurs when the incident xray photon with relatively high energy ejects an electron from an atom and a xray photon of lower energy is scattered from the atom. Pair production, in physics, formation or materialization of two electrons, one negative and the other positive positron, from a pulse of electromagnetic energy traveling through matter, usually in the vicinity of an atomic nucleus. Why is pair production not possible in empty space. The corresponding momenta are p 1 e 1 c hf 1 h 1 and p 2 e 2 c hf 2 h 2 using f c. The probability of pair production, characterized by cross section, is a very complicated function based on quantum mechanics. Compton normalized pair prod cross section vs fractional electron energy for photons of variouos energy no screening case 1 comptons equation let 1 and 2 be the wavelengths of the incident and scattered x rays, respectively, as shown in figure 318. Compton effect the photoelectric effect and einsteins theories about light having a particle nature caused a lot of scientists to start to reexamine some basic ideas, as well as come up with some new ones. These are the photoelectric effect, compton scattering, and pair production.
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