RSO Radiation Physics and Fundamentals 3

Question 1

The photoelectric effect is the dominant interaction of low-energy photons with matter. In this process, the photon is:

Accepted Answer

Completely absorbed and a bound electron is ejected from the atom

Answer

Scattered with reduced energy and a recoil electron is produced

Answer

Converted into an electron-positron pair

Answer

Reflected off the atomic nucleus

Question 2

Compton scattering is the dominant interaction of medium-energy photons with matter. Which of the following best describes this process?

Accepted Answer

The photon scatters off a free or loosely bound electron, losing some energy

Answer

The photon is totally absorbed and an electron is emitted

Answer

The photon is converted into an electron-positron pair

Answer

The photon interacts with the nucleus causing fission

Question 3

Pair production can only occur when the incident photon energy exceeds:

Accepted Answer

1.022 MeV

Answer

0.511 MeV

Answer

2.044 MeV

Answer

0.255 MeV

Question 4

Which property of a material is most important in determining its effectiveness as shielding against neutrons?

Accepted Answer

High hydrogen content

Answer

High atomic number (Z)

Answer

High density

Answer

High electron density

Question 5

Linear attenuation coefficient (μ) is used to describe photon beam attenuation in matter. Which formula correctly represents the intensity of a narrow photon beam after passing through a thickness x of a material?

Accepted Answer

I = I₀ × e^(-μx)

Answer

I = I₀ × e^(μx)

Answer

I = I₀ / (μx)

Answer

I = I₀ × (1 - μx)

Question 6

The tenth-value layer (TVL) of a shielding material is the thickness that reduces radiation intensity to one-tenth of its original value. What is the mathematical relationship between TVL and the linear attenuation coefficient (μ)?

Accepted Answer

TVL = ln(10) / μ

Answer

TVL = μ / ln(10)

Answer

TVL = 1 / (10μ)

Answer

TVL = ln(2) / μ

Question 7

When fast neutrons are slowed down (moderated) to thermal energies, the process is primarily achieved by:

Accepted Answer

Elastic scattering collisions with light nuclei

Answer

Photoelectric absorption in high-Z materials

Answer

Pair production interactions

Answer

Compton scattering with orbital electrons