NRRPT Detection and Measurement 2

Question 1

Which detector type operates on the principle of collecting ion pairs produced by radiation in a gas-filled chamber?

Accepted Answer

Ionization chamber

Answer

Ionization chambers collect the ion pairs (positive ions and electrons) produced when radiation ionizes the fill gas, generating a measurable current.

Question 2

A Geiger-Mueller tube operating in the 'plateau' region of its voltage-response curve indicates:

Accepted Answer

Optimal operating voltage where count rate is stable despite small voltage variations

Answer

The plateau region is the recommended operating range where the count rate remains relatively constant with small voltage fluctuations, ensuring reliable detection.

Question 3

What is the primary advantage of a NaI(Tl) scintillation detector over a GM tube for gamma spectroscopy?

Accepted Answer

Ability to discriminate photon energies and perform spectroscopy

Answer

NaI(Tl) detectors produce light pulses proportional to photon energy, enabling gamma-ray spectroscopy and radionuclide identification, which GM tubes cannot do.

Question 4

The 'dead time' of a radiation detector refers to:

Accepted Answer

The period after a count during which the detector cannot register another event

Answer

Dead time is the brief recovery period after each detected event during which the detector is insensitive to additional radiation, causing undercounting at high dose rates.

Question 5

A thermoluminescent dosimeter (TLD) measures absorbed dose by:

Accepted Answer

Measuring light emitted when heated crystals release stored energy

Answer

TLDs store energy from radiation in crystal lattice traps; when heated, electrons return to ground state and emit light proportional to the absorbed dose.

(NRRPT) National Registry of Radiation Protection Technicians Practice Test

(NRRPT) National Registry of Radiation Protection Technicians Practice Test

NRRPT Detection and Measurement 2