Among the many many science toys which have fallen out of vogue since we began getting nervous round issues like mercury, chlorinated hydrocarbons, and radiation is the spinthariscope, which let folks watch the flashes of sunshine on a phosphor display as a radioactive materials decayed behind it. In actual fact, they hardly expose their viewers to any radiation, which makes [stoppi]’s do-it-yourself spinthariscope a lot safer than it would first appear.
[Stoppi] constructed the spinthariscope out of the eyepiece of a telescope, a silver-doped zinc sulfide phosphor display, and the americium-241 capsule from a smoke detector. A little bit of epoxy holds the phosphor display within the lens’s focal airplane, and the americium capsule is mounted on a lightweight filter and screwed onto the eyepiece. Since americium is especially an alpha emitter, nearly all the radiation is contained throughout the system.
After sitting in a darkish room for a couple of minutes to let one’s eyes alter, it’s doable to see small flashes of sunshine as alpha particles hit the phosphor display. The flashes had been too faint for a smartphone digital camera to choose up, so [stoppi] mounted it in a light-tight metallic field with a photomultiplier and seen the sign on an oscilloscope, which revealed many small pulses.
Whereas a spinthariscope is a bit simpler to arrange, they’re significantly much less widespread amongst amateurs than are cloud chambers, one other option to view radioactive decay. For scientific devices, although, this mission’s scintillator-and-photomultiplier strategy is the usual, from tiny gamma ray spectrometers to large neutrino detectors.
