Interaction of Ionizing Radiation With Matter

According to the Bragg curve for an alpha particle, where does the specific energy loss reach its maximum?

• Just after the particle enters the absorbing medium.

• Very near the end of the particle's track, just before it stops.

• At a point exactly halfway through its range in the medium.

• The energy loss is constant throughout the particle's entire track.

What is the primary interaction mechanism by which alpha particles lose energy in matter?

• Coulomb forces with the orbital electrons of absorber atoms.

• Pair production by interacting with the nucleus.

• Elastic collisions with atomic nuclei.

• Bremsstrahlung radiation from rapid deceleration.

Which of the following conditions is required for pair production to occur?

• An incident alpha particle must collide with a heavy nucleus.

• An incident photon's energy must greater than the rest mass energy of an electron and positron combined.

• An incident neutron must have energy greater than 1.022 MeV.

• A low-energy photon interacts with a loosely bound outer-shell electron.

Which one of these processes involves a decrease in the energy of photon?

• bremsstrahlung

• photoelectric effect

• Compton scattering

• pair production

In Compton scattering, what is the relationship between the scattering angle θ of the photon and the energy transferred to the recoil electron?

• The energy transfer is highest when the scattering angle is 90 degree.

• The energy transfer is independent of the scattering angle.

• The energy transfer is highest when the scattering angle is 0 degree.

• The energy transfer is maximized when the scattering angle is 180 degree.

How is the 'range' of beta particles in an absorber typically specified to make it largely independent of the absorber material?

• In units of energy, such as MeV.

• In units of length, such as cm

• As a dimensionless ratio relative to the range in air.

• In units of density thickness, such as mg/cm²

What is a key difference between elastic and inelastic scattering of neutrons?

• Elastic scattering involves heavy nuclei, while inelastic scattering involves light nuclei.

• Kinetic energy is conserved in inelestic scattering but not in elastic scattering.

• In elastic scattering, the neutron is absorbed, while in inelastic scattering, it is not.

• In elastic scattering, the target nucleus remains in its ground state, while in inelastic scattering, it is left in an excited state.

The photoelectric effect is one of the three major interactions of gamma rays with matter. This effect is most dominant under which conditions?

• For high-energy photons (> 1.022 MeV) and high-Z materials.

• For any energy photon, as long as the material has a low work function.

• For low-energy photons and high atomic number (Z) materials.

Why does the absorption curve for monoenergetic alpha particles remain flat initially and then drop off sharply, unlike the curve for beta particles?

• Because alpha particles are much lighter than beta particles.

• Because alpha particles are uncharged and interact less frequently.

• Because alpha particles are monoenergetic and lose energy in many small interactions, giving them a definite range.

• Because alpha particles have a continuous energy spectrum.

According to the Bethe formula for nonrelativistic particles, how does the linear stopping power (−dE/dx) of a charged particle depend on its velocity (v)?

• It is directly proportional to its velocity (S ∝ v).

• It is directly proportional to the square of its velocity (S ∝ v²).

• It is independent of the particle's velocity.

• It is inversely proportional to the square of its velocity (S ∝ 1/v²).