Atomic Number: 55 Period Number: 6 Group Number: 1
Cesium (Caesium) is a soft and silvery-gold metal, which belongs to the alkali group. Cesium is a very rare element and two main sources for cesium-containing ore are Canada and Zimbabwe. Cesium, which is mined mostly from pollucite, has a total of 39 known isotopes.
Cesium iodide photocathodes are highly efficient at extreme ultraviolet wavelengths. An important application of cesium iodide crystals used as scintillator is for electromagnetic calorimetry in experimental particle physics.
Cesium Iodide (CsI) is used for scintillator technology in three main areas:
Medical PET and CAT scanners
Industrial and security inspection/detection x-ray scanners