NRRPT Physics and Interactions 2

Question 1

What is the primary interaction mechanism of alpha particles with matter?

Accepted Answer

Coulombic interactions with orbital electrons

Answer

Alpha particles lose energy primarily through Coulombic (electrostatic) interactions with the orbital electrons of atoms in the absorbing material.

Question 2

The linear energy transfer (LET) of a radiation type is best described as:

Accepted Answer

Energy deposited per unit path length in an absorber

Answer

LET is defined as the energy deposited per unit path length (keV/μm) and characterizes how densely ionizing a radiation type is.

Question 3

Which process is responsible for the production of characteristic X-rays?

Accepted Answer

Photoelectric effect

Answer

The photoelectric effect ejects an inner-shell electron; when an outer-shell electron fills the vacancy, a characteristic X-ray is emitted with energy equal to the difference in binding energies.

Question 4

The Q-value of a nuclear reaction is defined as:

Accepted Answer

The difference in rest-mass energies between reactants and products

Answer

The Q-value equals (sum of reactant rest masses minus sum of product rest masses) × c², representing the energy released (positive Q) or absorbed (negative Q) in the reaction.

Question 5

Pair production requires a minimum photon energy of approximately:

Accepted Answer

1.022 MeV

Answer

Pair production creates an electron-positron pair, each with rest mass energy of 0.511 MeV, so the threshold is 2 × 0.511 = 1.022 MeV.

(NRRPT) National Registry of Radiation Protection Technicians Practice Test

(NRRPT) National Registry of Radiation Protection Technicians Practice Test

NRRPT Physics and Interactions 2