A report on X-ray, Light and Compton scattering

Natural color x-ray photogram of a wine scene

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

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.

Example of a Crookes tube, a type of discharge tube that emitted X-rays

The electromagnetic spectrum, with the visible portion highlighted

Fig. 3: Energies of a photon at 500 keV and an electron after Compton scattering.

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

Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily

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.

$Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.$

Surgical removal of a bullet whose location was diagnosed with X-rays (see inset) in 1897

Hong Kong illuminated by colourful artificial lighting.

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.

$Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.$

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.

X-rays are part of the electromagnetic spectrum, with wavelengths shorter than UV light. Different applications use different parts of the X-ray spectrum.

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

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

If it results in a decrease in energy (increase in wavelength) of the photon (which may be an X-ray or gamma ray photon), it is called the Compton effect.

- Compton scattering

In this sense, gamma rays, X-rays, microwaves and radio waves are also light.

- Light

At energies of a few eV to a few keV, corresponding to visible light through soft X-rays, a photon can be completely absorbed and its energy can eject an electron from its host atom, a process known as the photoelectric effect.

- Compton scattering

He based it on the electromagnetic theory of light.

- X-ray

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

- X-ray

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.

- Light

3 related topics with Alpha

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.

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.

Electromagnetic spectrum with visible light highlighted

Rough plot of Earth's atmospheric absorption and scattering (or opacity) of various wavelengths of electromagnetic radiation

It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

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

Electron

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Subatomic particle whose electric charge is negative one elementary charge.

A beam of electrons deflected in a circle by a magnetic field

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.

In his 1924 dissertation Recherches sur la théorie des quanta (Research on Quantum Theory), French physicist Louis de Broglie hypothesized that all matter can be represented as a de Broglie wave in the manner of light.

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

An electron beam can be used to supplement the treatment of areas that have been irradiated by X-rays.

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

Photoelectric effect

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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.

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.

The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material.

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.

Because the kinetic energy of the emitted electrons is exactly the energy of the incident photon minus the energy of the electron's binding within an atom, molecule or solid, the binding energy can be determined by shining a monochromatic X-ray or UV light of a known energy and measuring the kinetic energies of the photoelectrons.