Cesium iodide (chemical formula :CsI) is an inorganic ionic compound commonly used as an input fluorescent agent in fluorescent display devices such as X-ray image multiplication tubes. Cesium iodide cathode tubes have high detection efficiency for strong ultraviolet wavelengths. Cesium iodide crystals are often used as scintillator materials for electromagnetic calorimeters in particle physics experiments. Pure cesium iodide is a fast, high-density scintillator material with a relatively high amount of luminescence. The light emitted has two main components: wavelengths in the near-ultraviolet region of 310 nm and 460 nm.