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Questions and Answers
What phenomenon occurs when an incident photon collides with a K-shell electron, resulting in the ejection of the electron?
What phenomenon occurs when an incident photon collides with a K-shell electron, resulting in the ejection of the electron?
Which interaction is more likely to occur with low energy photons and elements with high atomic numbers?
Which interaction is more likely to occur with low energy photons and elements with high atomic numbers?
What is the K-edge in the context of X-ray interactions?
What is the K-edge in the context of X-ray interactions?
How does the probability of the photoelectric effect occurring relate to atomic number?
How does the probability of the photoelectric effect occurring relate to atomic number?
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What is required for pair production to occur?
What is required for pair production to occur?
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Which statement is true about the Compton effect?
Which statement is true about the Compton effect?
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What particles are produced during pair production?
What particles are produced during pair production?
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Which of the following elements has the highest binding energy for a K-shell electron?
Which of the following elements has the highest binding energy for a K-shell electron?
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Study Notes
X-ray Interactions with Matter
- X-ray interactions are classified into two categories: photon scattering and photon disappearance.
Photon Scattering
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Compton scattering: Occurs when an x-ray photon collides with a loosely bound electron, usually in the outer shell.
- The electron receives a portion of the photon's energy, resulting in a scattered photon with lower energy traveling in a different direction.
Photon Disappearance
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Photoelectric effect: An incident photon interacts with a tightly bound electron in an inner shell, typically the K-shell, and ejects it from the atom.
- The entire photon's energy is absorbed by the electron, which is then ejected as a photoelectron.
- This creates a vacancy in the inner shell that is filled by an electron from a higher energy level.
- This process releases characteristic x-ray photons with energy equal to the difference between the two energy levels.
- The probability of the photoelectric effect increases significantly when the photon energy is slightly greater than the electron's binding energy, creating a sharp rise in the absorption curve known as a K-edge.
- The photoelectric effect is more likely to occur with low-energy photons and elements with high atomic numbers.
- The probability is directly proportional to the atomic number (Z) cubed (Z³) and inversely proportional to the photon energy cubed (E³).
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Pair production: A very energetic photon interacts with the nucleus, causing the photon to disappear and its energy to transform into matter in the form of an electron and a positron.
- A positron is an antiparticle with the same mass as an electron but a positive charge.
- The minimum photon energy required for pair production is 1.022 MeV, which is the combined rest mass energy of an electron and a positron (2 x 0.511 MeV).
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Positron annihilation: A positron interacts with a free electron, resulting in the annihilation of both particles and the release of two photons, each with an energy of 0.511 MeV, in opposite directions.
- This process conserves energy and momentum.
- Two mass units are converted into energy, resulting in a total energy of 1.022 MeV.
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Description
Test your knowledge on X-ray interactions including photon scattering and disappearance. This quiz covers phenomena such as Compton scattering and the photoelectric effect, detailing how X-rays interact with electrons in various shells. Challenge yourself to understand the energy transformations and implications involved in these processes.
