In condensed matter physics, scintillation (/ ˈ s ɪ n t ɪ l eɪ ʃ ən / SIN -til-ay-shun) is the physical process where a material, called a scintillator, emits ultraviolet or visible light under excitation from high energy photons (X-rays or gamma rays) or energetic particles (such as electrons, alpha particles, neutrons, or ions). See scintillator and scintillation counter for practical applications.