What is a gamma-ray spectrometer used for?

• A. To measure ambient dose rates.
• B. To identify radionuclides by their gamma energies.
• C. To measure neutron flux.
• D. To identify and quantify gamma-emitting radionuclides and their energies.

Answer: (D)

Identifying and quantifying gamma-emitting radionuclides by their gamma-ray energies. A gamma-ray spectrometer detects the energies of photons emitted by radioactive sources and records a spectrum where each peak corresponds to a specific gamma energy. Those energies are unique to particular nuclides, so by calibrating the energy scale and matching observed peaks to known gamma lines you can identify which radionuclides are present. The area under each peak, once you correct for background and detector efficiency, gives the activity of that radionuclide, allowing quantitative analysis. This capability distinguishes it from simple dose-rate measurements, which tell you how much radiation is present but not which nuclides, and from neutron detectors, which measure neutrons rather than gamma rays.