A report on Compton scattering

Fig. 1: Schematic diagram of Compton's experiment. Compton scattering occurs in the graphite target on the left. The slit passes X-ray photons scattered at a selected angle. The energy of a scattered photon is measured using Bragg scattering in the crystal on the right in conjunction with ionization chamber; the chamber could measure total energy deposited over time, not the energy of single scattered photons.
Fig. 3: Energies of a photon at 500 keV and an electron after Compton scattering.

Scattering of a high frequency photon after an interaction with a stationary charged particle, usually an electron.

- Compton scattering
Fig. 1: Schematic diagram of Compton's experiment. Compton scattering occurs in the graphite target on the left. The slit passes X-ray photons scattered at a selected angle. The energy of a scattered photon is measured using Bragg scattering in the crystal on the right in conjunction with ionization chamber; the chamber could measure total energy deposited over time, not the energy of single scattered photons.

24 related topics with Alpha

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Photons are emitted by a cyan laser beam outside, orange laser beam inside calcite and its fluorescence

Photon

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Elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force.

Elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force.

Photons are emitted by a cyan laser beam outside, orange laser beam inside calcite and its fluorescence
Photoelectric effect: the emission of electrons from a metal plate caused by light quanta – photons.
The cone shows possible values of wave 4-vector of a photon. The "time" axis gives the angular frequency (rad⋅s−1) and the "space" axis represents the angular wavenumber (rad⋅m−1). Green and indigo represent left and right polarization
Thomas Young's double-slit experiment in 1801 showed that light can act as a wave, helping to invalidate early particle theories of light.
In 1900, Maxwell's theoretical model of light as oscillating electric and magnetic fields seemed complete. However, several observations could not be explained by any wave model of electromagnetic radiation, leading to the idea that light-energy was packaged into quanta described by . Later experiments showed that these light-quanta also carry momentum and, thus, can be considered particles: The photon concept was born, leading to a deeper understanding of the electric and magnetic fields themselves.
Up to 1923, most physicists were reluctant to accept that light itself was quantized. Instead, they tried to explain photon behaviour by quantizing only matter, as in the Bohr model of the hydrogen atom (shown here). Even though these semiclassical models were only a first approximation, they were accurate for simple systems and they led to quantum mechanics.
Photons in a Mach–Zehnder interferometer exhibit wave-like interference and particle-like detection at single-photon detectors.
Stimulated emission (in which photons "clone" themselves) was predicted by Einstein in his kinetic analysis, and led to the development of the laser. Einstein's derivation inspired further developments in the quantum treatment of light, which led to the statistical interpretation of quantum mechanics.
Different electromagnetic modes (such as those depicted here) can be treated as independent simple harmonic oscillators. A photon corresponds to a unit of energy E = hν in its electromagnetic mode.

In part, the change can be traced to experiments such as those revealing Compton scattering, where it was much more difficult not to ascribe quantization to light itself to explain the observed results.

Natural color x-ray photogram of a wine scene

X-ray

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Penetrating form of high-energy electromagnetic radiation.

Penetrating form of high-energy electromagnetic radiation.

Natural color x-ray photogram of a wine scene
Example of a Crookes tube, a type of discharge tube that emitted X-rays
Wilhelm Röntgen
Hand mit Ringen (Hand with Rings): print of Wilhelm Röntgen's first "medical" X-ray, of his wife's hand, taken on 22 December 1895 and presented to Ludwig Zehnder of the Physik Institut, University of Freiburg, on 1 January 1896
Taking an X-ray image with early Crookes tube apparatus, late 1800s. The Crookes tube is visible in center. The standing man is viewing his hand with a fluoroscope screen. The seated man is taking a radiograph of his hand by placing it on a photographic plate. No precautions against radiation exposure are taken; its hazards were not known at the time.
Surgical removal of a bullet whose location was diagnosed with X-rays (see inset) in 1897
Images by James Green, from "Sciagraphs of British Batrachians and Reptiles" (1897), featuring (from left) Rana esculenta (now Pelophylax lessonae), Lacerta vivipara (now Zootoca vivipara), and Lacerta agilis
1896 plaque published in "Nouvelle Iconographie de la Salpetrière", a medical journal. In the left a hand deformity, in the right same hand seen using radiography. The authors named the technique Röntgen photography.
A patient being examined with a thoracic fluoroscope in 1940, which displayed continuous moving images. This image was used to argue that radiation exposure during the X-ray procedure would be negligible.
Chandra's image of the galaxy cluster Abell 2125 reveals a complex of several massive multimillion-degree-Celsius gas clouds in the process of merging.
Phase-contrast X-ray image of spider
X-rays are part of the electromagnetic spectrum, with wavelengths shorter than UV light. Different applications use different parts of the X-ray spectrum.
Ionizing radiation hazard symbol
Attenuation length of X-rays in water showing the oxygen absorption edge at 540 eV, the energy−3 dependence of photoabsorption, as well as a leveling off at higher photon energies due to Compton scattering. The attenuation length is about four orders of magnitude longer for hard X-rays (right half) compared to soft X-rays (left half).
Spectrum of the X-rays emitted by an X-ray tube with a rhodium target, operated at 60 kV. The smooth, continuous curve is due to bremsstrahlung, and the spikes are characteristic K lines for rhodium atoms.
Patient undergoing an x-ray exam in a hospital radiology room.
A chest radiograph of a female, demonstrating a hiatal hernia
Plain radiograph of the right knee
Head CT scan (transverse plane) slice – a modern application of medical radiography
Abdominal radiograph of a pregnant woman, a procedure that should be performed only after proper assessment of benefit versus risk
Each dot, called a reflection, in this diffraction pattern forms from the constructive interference of scattered X-rays passing through a crystal. The data can be used to determine the crystalline structure.
Using X-ray for inspection and quality control: the differences in the structures of the die and bond wires reveal the left chip to be counterfeit.
X-ray fine art photography of needlefish by Peter Dazeley

X-rays interact with matter in three main ways, through photoabsorption, Compton scattering, and Rayleigh scattering.

Hydrogen atomic orbitals at different energy levels. The more opaque areas are where one is most likely to find an electron at any given time.

Electron

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Subatomic particle whose electric charge is negative one elementary charge.

Subatomic particle whose electric charge is negative one elementary charge.

Hydrogen atomic orbitals at different energy levels. The more opaque areas are where one is most likely to find an electron at any given time.
A beam of electrons deflected in a circle by a magnetic field
J. J. Thomson
Robert Millikan
The Bohr model of the atom, showing states of an electron with energy quantized by the number n. An electron dropping to a lower orbit emits a photon equal to the energy difference between the orbits.
In quantum mechanics, the behavior of an electron in an atom is described by an orbital, which is a probability distribution rather than an orbit. In the figure, the shading indicates the relative probability to "find" the electron, having the energy corresponding to the given quantum numbers, at that point.
Standard Model of elementary particles. The electron (symbol e) is on the left.
Example of an antisymmetric wave function for a quantum state of two identical fermions in a 1-dimensional box. If the particles swap position, the wave function inverts its sign.
A schematic depiction of virtual electron–positron pairs appearing at random near an electron (at lower left)
A particle with charge q (at left) is moving with velocity v through a magnetic field B that is oriented toward the viewer. For an electron, q is negative so it follows a curved trajectory toward the top.
Here, Bremsstrahlung is produced by an electron e deflected by the electric field of an atomic nucleus. The energy change E2 − E1 determines the frequency f of the emitted photon.
Probability densities for the first few hydrogen atom orbitals, seen in cross-section. The energy level of a bound electron determines the orbital it occupies, and the color reflects the probability of finding the electron at a given position.
A lightning discharge consists primarily of a flow of electrons. The electric potential needed for lightning can be generated by a triboelectric effect.
Lorentz factor as a function of velocity. It starts at value 1 and goes to infinity as v approaches c.
Pair production of an electron and positron, caused by the close approach of a photon with an atomic nucleus. The lightning symbol represents an exchange of a virtual photon, thus an electric force acts. The angle between the particles is very small.
An extended air shower generated by an energetic cosmic ray striking the Earth's atmosphere
Aurorae are mostly caused by energetic electrons precipitating into the atmosphere.
During a NASA wind tunnel test, a model of the Space Shuttle is targeted by a beam of electrons, simulating the effect of ionizing gases during re-entry.

An inelastic collision between a photon (light) and a solitary (free) electron is called Compton scattering.

NASA guide to electromagnetic spectrum showing overlap of frequency between X-rays and gamma rays

Gamma ray

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Penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei.

Penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei.

NASA guide to electromagnetic spectrum showing overlap of frequency between X-rays and gamma rays
Radioactive decay scheme of
Gamma emission spectrum of cobalt-60
Image of entire sky in 100 MeV or greater gamma rays as seen by the EGRET instrument aboard the CGRO spacecraft. Bright spots within the galactic plane are pulsars while those above and below the plane are thought to be quasars.
A hypernova. Artist's illustration showing the life of a massive star as nuclear fusion converts lighter elements into heavier ones. When fusion no longer generates enough pressure to counteract gravity, the star rapidly collapses to form a black hole. Theoretically, energy may be released during the collapse along the axis of rotation to form a long duration gamma-ray burst.
Alpha radiation consists of helium nuclei and is readily stopped by a sheet of paper. Beta radiation, consisting of electrons or positrons, is stopped by an aluminium plate, but gamma radiation requires shielding by dense material such as lead or concrete.
The total absorption coefficient of aluminium (atomic number 13) for gamma rays, plotted versus gamma energy, and the contributions by the three effects. As is usual, the photoelectric effect is largest at low energies, Compton scattering dominates at intermediate energies, and pair production dominates at high energies.
The total absorption coefficient of lead (atomic number 82) for gamma rays, plotted versus gamma energy, and the contributions by the three effects. Here, the photoelectric effect dominates at low energy. Above 5 MeV, pair production starts to dominate.
Gamma-ray image of a truck with two stowaways taken with a VACIS (vehicle and container imaging system)
In practice, gamma ray energies overlap with the range of X-rays, especially in the higher-frequency region referred to as "hard" X-rays. This depiction follows the older convention of distinguishing by wavelength.
The Moon as seen by the Compton Gamma Ray Observatory, in gamma rays of greater than 20 MeV. These are produced by cosmic ray bombardment of its surface. The Sun, which has no similar surface of high atomic number to act as target for cosmic rays, cannot usually be seen at all at these energies, which are too high to emerge from primary nuclear reactions, such as solar nuclear fusion (though occasionally the Sun produces gamma rays by cyclotron-type mechanisms, during solar flares). Gamma rays typically have higher energy than X-rays.

Such electrons produce secondary gamma rays by the mechanisms of bremsstrahlung, inverse Compton scattering and synchrotron radiation.

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Electromagnetic radiation

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In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, propagating through space, carrying electromagnetic radiant energy.

In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, propagating through space, carrying electromagnetic radiant energy.

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Shows the relative wavelengths of the electromagnetic waves of three different colours of light (blue, green, and red) with a distance scale in micrometers along the x-axis.
In electromagnetic radiation (such as microwaves from an antenna, shown here) the term "radiation" applies only to the parts of the electromagnetic field that radiate into infinite space and decrease in intensity by an inverse-square law of power, so that the total radiation energy that crosses through an imaginary spherical surface is the same, no matter how far away from the antenna the spherical surface is drawn. Electromagnetic radiation thus includes the far field part of the electromagnetic field around a transmitter. A part of the "near-field" close to the transmitter, forms part of the changing electromagnetic field, but does not count as electromagnetic radiation.
Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This 3D animation shows a plane linearly polarized wave propagating from left to right. The electric and magnetic fields in such a wave are in-phase with each other, reaching minima and maxima together.
Representation of the electric field vector of a wave of circularly polarized electromagnetic radiation.
James Clerk Maxwell
Electromagnetic spectrum with visible light highlighted
Rough plot of Earth's atmospheric absorption and scattering (or opacity) of various wavelengths of electromagnetic radiation

Eventually Einstein's explanation was accepted as new particle-like behavior of light was observed, such as the Compton effect.

The emission of electrons from a metal plate caused by light quanta – photons.

Photoelectric effect

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Emission of electrons when electromagnetic radiation, such as light, hits a material.

Emission of electrons when electromagnetic radiation, such as light, hits a material.

The emission of electrons from a metal plate caused by light quanta – photons.
Schematic of the experiment to demonstrate the photoelectric effect. Filtered, monochromatic light of a certain wavelength strikes the emitting electrode (E) inside a vacuum tube. The collector electrode (C) is biased to a voltage VC that can be set to attract the emitted electrons, when positive, or prevent any of them from reaching the collector when negative.
Diagram of the maximum kinetic energy as a function of the frequency of light on zinc.
The gold leaf electroscope to demonstrate the photoelectric effect. When the electroscope is negatively charged, there is an excess of electrons and the leaves are separated. If short wavelength, high-frequency light (such as ultraviolet light obtained from an arc lamp, or by burning magnesium, or by using an induction coil between zinc or cadmium terminals to produce sparking) shines on the cap, the electroscope discharges, and the leaves fall limp. If, however, the frequency of the light waves is below the threshold value for the cap, the leaves will not discharge, no matter how long one shines the light at the cap.
Photomultiplier
Angle-resolved photoemission spectroscopy (ARPES) experiment. Helium discharge lamp shines ultraviolet light onto the sample in ultra-high vacuum. Hemispherical electron analyzer measures the distribution of ejected electrons with respect to energy and momentum.

While free electrons can absorb any energy when irradiated as long as this is followed by an immediate re-emission, like in the Compton effect, in quantum systems all of the energy from one photon is absorbed—if the process is allowed by quantum mechanics—or none at all.

Compton in 1927

Arthur Compton

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Compton in 1927
Compton and Werner Heisenberg in 1929 in Chicago
Compton on the cover of Time magazine on January 13, 1936, holding his cosmic ray detector
Compton at the University of Chicago in 1933 with graduate student Luis Alvarez next to his cosmic ray telescope.
Arthur Compton's ID badge from the Hanford Site. For security reasons he used a pseudonym.
Compton's house in Chicago, now a national landmark
The Compton Gamma Ray Observatory released into Earth's orbit in 1991

Arthur Holly Compton (September 10, 1892 – March 15, 1962) was an American physicist who won the Nobel Prize in Physics in 1927 for his 1923 discovery of the Compton effect, which demonstrated the particle nature of electromagnetic radiation.

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.

Light

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Electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye.

Electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye.

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.
The electromagnetic spectrum, with the visible portion highlighted
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Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily
Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.
Hong Kong illuminated by colourful artificial lighting.
Pierre Gassendi.
Christiaan Huygens.
Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.
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In 1923 Arthur Holly Compton showed that the wavelength shift seen when low intensity X-rays scattered from electrons (so called Compton scattering) could be explained by a particle-theory of X-rays, but not a wave theory.

Washington University in St. Louis

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Private research university with its main campus in St. Louis County, and Clayton, Missouri.

Private research university with its main campus in St. Louis County, and Clayton, Missouri.

William Greenleaf Eliot, first president of the Board of Trustees
Robert S. Brookings
The Washington University crest at the entrance to Francis Field
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Graham Chapel
Brookings Hall Quad
Danforth Campus Buildings
2008 Vice Presidential Debate at the Washington University Field House
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The Washington University Medical Center as seen from Forest Park
Holmes Lounge, the central reading room on campus, where students may study
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The Mildred Lane Kemper Art Museum
Cupples Hall
Anheuser Busch Hall, home to the School of Law
Washington University School of Medicine
Seigle Hall, shared by the School of Law and the College of Arts and Sciences
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Brown Hall
Olin Library
Reading room in Anheuser-Busch Hall
Women's Building
McMillan Hall
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Francis Olympic Field during the 1904 St. Louis Olympics
Gates at Francis Field
Jim McKelvey, co-founder and director of Block, Inc.
Charles Nagel, Founder of the United States Chamber of Commerce
J. C. R. Licklider, Pioneer in artificial intelligence and the Internet
Peter Sarsgaard, Award-winning actor
Clyde Cowan, Co-discoverer of the Neutrino
Phoebe Couzins, First woman U.S. Marshal
Arthur Holly Compton, Discoverer of the Compton effect
Peter Mutharika, President of Malawi
Edward Adelbert Doisy, Discoverer of Vitamin K
Gerty Cori, First woman to be awarded the Nobel Prize in Physiology or Medicine
Douglass North, Nobel Laureate Economist
Alfred Hershey, Nobel Laureate bacteriologist known for the Hershey–Chase experiment
Joseph W. Kennedy, Co-discoverer of Plutonium
alt=Bob Behnken is a NASA Astronaut and Test Engineer.|Bob Behnken, NASA Astronaut, Test engineer
alt=https://theactionalliance.org/about/staff/rochelle-p-walensky-md-mph|Rochelle Walensky,<ref>{{Cite web |last=Freyer |first=Felice |date=December 7, 2020 |title=Dr. Rochelle Walensky, Biden’s choice for CDC chief, brings stellar reputation as scientist and communicator |url=https://www.bostonglobe.com/2020/12/07/metro/dr-rochelle-walensky-bidens-choice-cdc-chief-brings-stellar-reputation-scientist-communicator/ |website=The Boston Globe |access-date=July 31, 2022 |archive-date=April 28, 2022 |archive-url=https://web.archive.org/web/20220428184012/https://www.bostonglobe.com/2020/12/07/metro/dr-rochelle-walensky-bidens-choice-cdc-chief-brings-stellar-reputation-scientist-communicator/ |url-status=live }}</ref> 19th Director of the Centers for Disease Control and Prevention

Compton's discovery, known as the "Compton Effect," earned him the Nobel Prize in physics in 1927.

Walther Bothe in the 1950s

Walther Bothe

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German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born.

German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born.

Walther Bothe in the 1950s
Walther Bothe

Upon his return to the laboratory, he developed and applied coincidence methods to the study of nuclear reactions, the Compton effect, cosmic rays, and the wave–particle duality of radiation, for which he would receive the Nobel Prize in Physics in 1954.