A scintillometer measures ionizing radiation. The sensor is a crystal that fluoresces when ionizing radiation hits it. A sensitive photocell measures the light from the crystal. The photocell is attached to an electronic amplifier and possibly other electronic equipment.
Scintillometers are the most sensitive known radiation detectors.
... Ibn Battuta, (1304?-1377?), Moroccan Muslim, visited Mecca several times, travelled to Central Asia, East Africa, China, Tombouctou and other places
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