Spinthariscope

A spinthariscope (/spɪnˈθærɪskoʊp/)^[2][3] is a device for observing individual nuclear disintegrations caused by the interaction of ionizing radiation with a phosphor (see radioluminescence) or scintillator.

A low quality toy spinthariscope taken from a 1950s Chemcraft brand "Atomic energy" chemistry experimentation set

A spinthariscope crafted by Robert Drosten in Belgium in 1905 and used in the University of Mons Faculty of Engineering ("Polytech Mons") at the beginning of the 20th century.^[1]

Invention

The spinthariscope was invented by William Crookes in 1903.^[4][5] 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.^[6] 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 Ancient Greek: σπινθήρ (spinthḗr) "spark".^[7]

Crookes debuted the spinthariscope at a meeting of the Royal Society, London on 15 May 1903.^[8]

Toy spinthariscopes

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.^[9] 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 (equivalent to $2.11 in 2024).^[10][11][12] 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.^{[citation needed]}

In museums

The American History Museum of the Smithsonian has several spinthariscopes in its collections, and an article discussing them.^[13] However, as of 2022^[update] none are currently on display.^[14]