NRRPT Physics and Interactions 5

Question 1

Internal conversion (IC) electrons are emitted with energies equal to:

Accepted Answer

The gamma-ray energy minus the electron's atomic binding energy

Answer

In internal conversion, the nuclear excitation energy is transferred directly to an orbital electron; the electron is ejected with energy equal to the gamma-ray energy minus its atomic binding energy.

Question 2

Which interaction dominates for low-energy photons (<100 keV) in high-Z materials?

Accepted Answer

Photoelectric effect

Answer

The photoelectric effect dominates at low photon energies and is proportional to Z⁴–Z⁵, making it dominant in high-Z materials at energies below ~100 keV.

Question 3

The specific ionization of a charged particle in air generally increases as the particle slows down near the end of its range, forming a region known as the:

Accepted Answer

Bragg peak

Answer

As heavy charged particles slow near the end of their range, the interaction cross section increases, producing a sharp maximum in ionization density called the Bragg peak.

Question 4

A radionuclide decays by beta-minus emission. Which statement about the emitted beta particle energy spectrum is correct?

Accepted Answer

It is a continuous spectrum with a maximum energy (Emax)

Answer

Beta particles are emitted with a continuous spectrum from near zero up to Emax because the available decay energy is shared between the beta particle and the antineutrino.

Question 5

The nuclear binding energy per nucleon is greatest for nuclides near which mass number?

Accepted Answer

A ≈ 56 (iron)

Answer

The binding energy per nucleon curve peaks around A = 56 (iron-56), which is why fusion of light elements and fission of heavy elements both release energy.

(NRRPT) National Registry of Radiation Protection Technicians Practice Test

(NRRPT) National Registry of Radiation Protection Technicians Practice Test

NRRPT Physics and Interactions 5