What describes a scintillation detector used in gamma spectroscopy?

• A. A detector using a scintillating material (e.g., NaI(Tl)) to measure gamma radiation.
• B. A detector that detects neutrons using a scintillating material.
• C. A device that measures gamma radiation using a semiconductor detector.
• D. A detector that measures infrared light from radiation.

Answer: (A)

A scintillation detector in gamma spectroscopy uses a crystal that emits light when a gamma photon deposits energy in it. That light is then converted into an electrical signal by a photomultiplier tube (or similar device). The pulse height is proportional to the energy deposited, so by collecting many pulses you build a spectrum with peaks at the gamma energies from the source. NaI(Tl) is a classic choice because it produces a bright light signal and provides good efficiency and reasonably good energy resolution, making it practical for identifying gamma-emitting isotopes.

Other approaches mentioned would not describe a scintillation detector for gamma rays: detecting neutrons often uses different materials or configurations; a semiconductor detector (like HPGe or silicon) relies on solid-state charge collection rather than scintillation; infrared light is outside the gamma regime and isn’t used for gamma spectroscopy.