COMPTON SCATTERING

 According to the  American Physical Society ( APS) Physics, Compton scattering is important for : Radiobiology -  the most probable interaction of gamma rays and high energy X-rays with atomic nuclei in living beings and is applied in radiation therapy  Material physics -  used to probe the wave function of the electrons in matter. Gamma spectroscopy   -  gives rise to the Compton edge , as it is possible for the gamma rays to scatter out of the detectors used. Diagnostic radiography -  relates to differences in the way photons are absorbed by various anatomic structures. -      The number of photoelectric and Compton interactions is greater in hard tissues compared to soft tissues -     M ore photons in the beam exit the patient after passing through soft tissue than through hard tissue.  -     Thus, it a llows a radiograph to provide a clear image of enamel, dentine, and bone and also, soft tissue.

As we all know, light is made up of particles called photons , and it has momentum which can be seen when a photon with high energy collides with a stationary electron. Some of the energy and momentum are transferred to the electron (known as the Compton effect), but both momentum and energy are conserved in this elastic collision. After the collision, the photon has energy hf /  and the electron has acquired a kinetic energy K.  Conservation of energy: hf = hf/ + K Combining this with the momentum conservation equations , it can be shown that the wavelength of the outgoing photon is related to the wavelength of the incident photon by the equation: Δλ = λ/ - λ = (h/ m e c ) (1 - cosθ) h = Planck's Constant =  6.62x10 -34 m 2 kg/s m e = Mass of electron =  9.11x10 -31 kg c = Speed of light =  3x10 8 m /s The collision causes the photon wavelength to increase by somewhere between 0 (for a scattering angle of 0°) and twice the Compton wavelength (for a scattering ...

  So, based on the Crompton Scattering formula that we discuss on the previous post, today we will share a short, understandable youtube video example question on Crompton Scattering by Michel Van Biezen .  How to find the wavelength of the scattered photon using the Crompton Scattering equation

Experimental goals In this experiment, you will measure: 1. the energies of Compton-scattered gamma-ray photons and recoil electrons, 2. the frequency of scattering as a function of angle,  θ, and 3. the total cross section of electrons for Compton scattering. Experimental arrangement The experimental arrangement for the Compton experiment is shown schematically in Figure 1. The 2”x2”  cylindrical “recoil electron” or “target” scintillator detector (Canberra model 802-3/2007), is irradiated by a  beam of 661.6 keV photons emitted by about 100 µCi  (≈ 1 microgram!) of 137Cs located at the end of a hole in  a large lead brick which acts as a gamma-ray “howitzer”.  If a photon entering the target scintillator scatters from  a loosely bound, effectively free, electron, the resulting  recoil electron may lose all of its energy in the target,  causing a scintillation pulse with an amplitude proportional to the energy of the recoil electron. If the ...

  The popular Compton scattering focuses on the wave side of quantum phenomena rather than the particle aspect. It had been observed that the wavelength of X-rays is increased when they are scattered off matter. Arthur Compton (1892-1962) showed that this behavior could be explained by assuming that the X-rays were photons (light quantum). When photons are scattered off electrons, part of their energy is transferred to the electrons. The loss of energy is translated into a reduction of frequency, which in turn leads to a lengthening of the wavelength of the scattered photons. This happens because the relation E=hv=hc/ λ holds. In these experiments, first carried out between 1919 and 1922, the scattering of X-rays is treated as a collision of photons and electrons. EXPERIMENTAL SETUP: Monochromatic X-rays with wavelength   λ  are incident on a sample of graphite (the “target”), where they interact with atoms inside the sample; they later emerge as scattered X-rays with wav...

Radiation Therapy An application of Compton scattering can be seen from the theme of radiobiology where it is applied in radiation therapy. This happens due to it being the most probable interaction of high energy X-rays with atomic nuclei in living beings. It also produces high-energy photon beams, peaked at the high energy and having small divergence which is preferable in radiotherapy.  Compton backscattering, in this case, is an alternate method of photon production for cancer treatment. It is evident that the photons scattered in the direction opposite to the direction of the initial photon (backscattered) will have the energy desired for photon beam therapy. The output of Compton backscattering is a high-energy photon beam (gamma-ray beam), which is well collimated and has minimal low-energy components. Such beams may be used for conventional high-energy photon treatments, production of radionuclides, and generation of positrons and neutrons. This process is basically Com...

      Compton Scatter Densitometer (CSD) The applications of CSD: 1. The electron density in certain volume of an object can be obtained. 2. A collimated detector is focused on a thin incident beam to measure the density of a small-volume element, and derive the physical density distribution, the element number or other relative information about an object. 3. The defects such as flaws, impurity or bubbles can be detected on the object. The advantages of CSD: 1. Compton scattering can give a higher yield of photon counts and can be applied to scattering at conveniently large angles. 2. By scanning the sample, it yields 3-dimessional (3D) information about the sample without computational reconstruction. 3. The detected contrast is larger than in transmission imaging, because changes are seen against a much smaller background signal. 4. It can be used in some applications where geometry constraints make transmission imaging difficult.

PoGOLite and Simulation of  Inverse Compton Scattering     PoGOLite is a polarized Gamma-ray Observer. the polarization measured through coincident detection of Compton scattering and photoabsorption. the compton emission being the emission mechanims for polarizing by aiding the accretion disks around BH's and neutron stars (Cygnus X-1). There are also plenty of detector unit created and formed in assisting the creation of PoGOLite.  This PoGOLite can be seen as per the prototype clipped below.  with the concept of Inverse Compton Scattering, the spectra will be detected by the detector. it will also help in the angle and degree of polarization. the concept also was defined as high electron energy approximation by Moskalenko and A. Strong (2000). the exact formula for several special cases was also created by G. Brunetti (2000) and can be seen as per below. 

  Others.  Compton Scatter Imaging (CSI) Compton Profile Analysis (CPI) Measurement of electron distribution of the scattered and electron momentum. The type of chemical bonds between electrons. Characterizing mineral density in the bone and composition in the tissue and measuring ash in coal and solid loading fraction in slurry  Compton Telescopes. for Omega ray astronomy Used to probe the wave function of the electrons in matter in the momentum representation. is an important effect in gamma spectroscopy which gives rise to the Compton edge, as it is possible for the gamma rays to scatter out of the detectors used. Compton suppression is used to detect stray scatter gamma rays to counteract this effect.

Compton scattering is known as an interaction between a free electron at rest and a high-energy photon (which is typically an x-ray or gamma-ray). Compton (1923) presented the first semi-quantum-mechanical treatment of such an interaction in 1923. In contrast, inverse Compton scattering (ICS) is known as an interaction between a high-energy electron and a low-energy photon. In such scattering, part of the energy of the electron is transferred to the scattering photon. In 1948, Feenberg and Primakoff (1948) first suggested the kinematic formulas for ICS and revealed that gamma-rays emitted from the vicinity of the Sun are produced by the interaction between the cosmic ray electrons and the Sun's light. The collision between a photon and an atomic electron The Compton effect occurs for most of the atomic electrons. A gamma photon plays the role of a projectile that collides with an electron in an atom that serves as a target. Gamma was represented as a punctual particle because of it...

 X-Ray Interactions for Radiography and CT Technologists Compton Scattering In x-ray imaging, Compton Scattering is the second most important impact. The x-ray photon interacts with an electron in the outer shell in this situation, and so the chance of Compton Scattering is unaffected by Z. The electron is knocked out by the X-Ray photon, as indicated in the diagram. To conserve momentum, the photon then travels in the opposite direction as the knocked-out electron. It's vital to keep in mind that, unlike the photoelectric effect, the energy isn't fully deposited locally in this case. A considerable portion of the energy of the entering photon may still be present in the scattered photon. It can still pass through the patient, where it may cause a secondary scatter effect or be detected by the detector. Photoelectric Effect The photoelectric effect is the most important factor in the formation of signal in an x-ray image because the x-ray will be stopped and its energy will be ...

 Scatter Radiation Most of the scatter radiation encountered in diagnostic radiology is caused by Compton scattering. The photon maintains its original energy in the diagnostic energy range. This poses a big problem because photons that are dispersed in narrow angles are able to reach and produce fog with x-ray film. It is extremely difficult to remove because: 1. cannot be removed by filters - too energetic 2. cannot be removed by grids - narrow angles of deflection Safety Hazard Even after 90 degrees of deflection, most of its original energy is maintained. It makes scatter radiation is as energetic as primary radiation.

Compton effect  or  Compton scatter  is one of the principal forms of  photon interaction . It is the leading cause of scattered radiation in a material. It occurs due to the exchange of the photon (x-ray or  gamma ) w ith free electrons (unattached to atoms) or loosely bound valence shell (outer shell) electrons. The resultant incident photon is scattered (changes direction) and imparts energy to the electron (recoil electron). The scattered photon will have a different wavelength (observed phenomenon) and other energy (E=hc/λ). Energy and momentum are conserved in this process. The Compton effect is a partial absorption process, and as the original photon has lost energy, known as Compton shift (i.e. a shift of wavelength/frequency). The wavelength change of the scattered photon can be determined by 0.024 (1- cos θ), where θ is the scattered photon angle. Thus, the energy of the scattered photon decreases with increasing scatter...

The energy of photons proportionates directly to their frequency and inversementally to their wavelength, so that the photons with less energy have less frequencies and longer wavelengths. Individual photons collide in the Compton effect with single electrons, freely or relatively loosely bound in matter atoms. Photons that collide transfer energy and momentum to electrons that retreat in turn. During the collision, new photons are produced with less energy and momentum, which are dispersed at corners, depending on the amount of energy lost to the electrons retrieving. Because of the connection between energy and wavelength, the dispersed photons have a longer wavelength depending on their angle size. The wavelength increase or Compton shift does not depend on the photon's wavelength. In early 1923, the Dutch physical chemist Peter Debye found the Compton effect to be independent.

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