A scintillation crystal is a type of material that emits flashes of light, or scintillations, when it absorbs ionizing radiation. These crystals are commonly used in radiation detection and measurement applications, such as in gamma-ray spectroscopy and medical imaging. The light produced can be detected and measured, allowing scientists and technicians to determine the type and energy of the radiation. These crystals are typically made from materials like sodium iodide or cesium iodide, which are effective at converting radiation energy into visible light. When radiation interacts with the crystal, it excites the atoms, leading to the emission of photons. This property makes scintillation crystals valuable in various fields, including nuclear medicine and particle physics.