NRRPT Detection and Measurement 3

Question 1

An OSL (optically stimulated luminescence) dosimeter differs from a TLD primarily in that it:

Accepted Answer

Uses light (laser) rather than heat to read out stored dose information

Answer

OSL dosimeters use laser light stimulation to release stored energy as luminescence, allowing non-destructive readout and the ability to re-read the same dosimeter multiple times.

Question 2

The Compton edge in a gamma-ray pulse-height spectrum represents:

Accepted Answer

The maximum energy transferred to a recoil electron in Compton scattering

Answer

The Compton edge is the maximum kinetic energy a recoil electron can receive from Compton scattering, which occurs when a photon backscatters at 180 degrees.

Question 3

What is the purpose of a moderator in a neutron rem meter (such as the Andersson-Braun rem meter)?

Accepted Answer

To slow fast neutrons to thermal energies where detection efficiency is higher

Answer

Moderating materials (typically polyethylene) slow fast neutrons through elastic scattering, converting them to thermal neutrons that are efficiently detected by the BF3 or He-3 tube.

Question 4

A survey meter with a pancake probe is particularly useful for:

Accepted Answer

Detecting low-energy beta and alpha contamination on surfaces

Answer

The thin window on a pancake GM probe allows low-energy beta particles and alpha particles to enter the detector, making it ideal for surface contamination surveys.

Question 5

The energy resolution of a germanium (HPGe) detector compared to NaI(Tl) is:

Accepted Answer

Significantly better, allowing discrimination of closely spaced gamma energies

Answer

HPGe detectors have energy resolution of ~0.1-0.2% FWHM compared to ~7% for NaI(Tl), enabling identification of radionuclides with very similar gamma-ray energies.

(NRRPT) National Registry of Radiation Protection Technicians Practice Test

(NRRPT) National Registry of Radiation Protection Technicians Practice Test

NRRPT Detection and Measurement 3