NRRPT Radiation Fundamentals & Detection 3

Question 1

The half-value layer (HVL) of a gamma-ray beam is 2 cm of lead. What thickness reduces the intensity to 12.5% of the original?

Accepted Answer

6 cm

Answer

4 cm

Answer

8 cm

Answer

10 cm

Question 2

In neutron activation analysis, what process produces radioactive isotopes from stable elements?

Accepted Answer

Radiative neutron capture (n,γ)

Answer

Neutron-proton reaction (n,p)

Answer

Neutron fission (n,f)

Answer

Inelastic neutron scattering (n,n')

Question 3

What does the energy resolution of a radiation detector describe?

Accepted Answer

The ability to distinguish between two close energy peaks

Answer

The minimum energy of radiation the detector can sense

Answer

The maximum dose rate the detector can measure

Answer

The efficiency of converting radiation to electrical signal

Question 4

A radionuclide has a physical half-life of 8 days and a biological half-life of 24 days. Its effective half-life is approximately:

Accepted Answer

6 days

Answer

32 days

Answer

16 days

Answer

4 days

Question 5

Which radiation type has the highest linear energy transfer (LET) in tissue?

Accepted Answer

5 MeV alpha particles

Answer

Cobalt-60 gamma rays

Answer

1 MeV beta particles

Answer

Diagnostic X-rays at 80 kVp

Question 6

What is the primary purpose of using a discriminator circuit in a radiation counting system?

Accepted Answer

To reject pulses below a set threshold, reducing noise counts

Answer

To amplify the detector signal before counting

Answer

To convert analog pulses to digital signals

Answer

To measure the energy of individual photons

Question 7

Pair production interactions require incident photon energies above:

Accepted Answer

1.022 MeV

Answer

0.511 MeV

Answer

1.25 MeV

Answer

2.044 MeV