A spinthariscope [1] is a device for observing individual nuclear disintegrations caused by the interaction of ionizing radiation with a phosphor (see radioluminescence) or scintillator.
The spinthariscope was invented by William Crookes in 1903.[2] [3] While observing the apparently uniform fluorescence on a zinc sulfide screen created by the radioactive emissions (mostly alpha radiation) of a sample of radium bromide, he spilled some of the sample, and, owing to its extreme rarity and cost, he was eager to find and recover it.[4] Upon inspecting the zinc sulfide screen under a microscope, he noticed separate flashes of light created by individual alpha particle collisions with the screen. Crookes took his discovery a step further and invented a device specifically intended to view these scintillations. It consisted of a small screen coated with zinc sulfide affixed to the end of a tube, with a tiny amount of radium salt suspended a short distance from the screen and a lens on the other end of the tube for viewing the screen. Crookes named his device from Greek, Ancient (to 1453);: σπινθήρ "spark".[5]
Crookes debuted the spinthariscope at a meeting of the Royal Society, London on 15 May 1903.[6]
Spinthariscopes were quickly replaced with more accurate and quantitative devices for measuring radiation in scientific experiments, but enjoyed a modest revival in the mid 20th century as children's educational toys.[7] In 1947, Kix cereal offered a Lone Ranger atomic bomb ring that contained a small one, in exchange for a box top and US$0.15 .[8] [9] [10] Spinthariscopes can still be bought today as instructional novelties, but they now use americium or thorium. Looking into a properly focused toy spinthariscope, one can see many flashes of light spread randomly across the screen. Almost all are circular, with a very bright pinpoint centre surrounded by a dimmer circle of emission.
The American History Museum of the Smithsonian has several spinthariscopes in its collections, and an article discussing them.[11] However, none are currently on display.[12]